REFERENCE COMPONENTS

COINCIDENT M300B FRANKENSTEIN MK II

UPDATED APRIL 2016

INTRODUCTION

PART ONE- MY RECENT (1987-2007) AMPLIFIER HISTORY

PART TWO- AN OVERVIEW AND PERSPECTIVE ON POWER AMPLIFIERS

PART THREE- THE FRANKENSTEIN'S SUPERIOR PERFORMANCE

PART FOUR- CONCLUSION

PART FIVE- SET-UP, BREAK-IN AND OPTIMIZATION

PART SIX- THE LATEST (SHINY STAINLESS STEEL) VERSION

PART SEVEN- TEFLON COUPLING CAPACITOR MODIFICATION AND COMPARISONS NEW!

OCTOBER 2005 ESSAY ON THE ORIGINAL "FRANKENSTEIN" AMPLIFIER

READERS LETTERS

INTERNAL LINKS

INTRODUCTION

This is, without a doubt, the finest amplifier, overall, I have ever heard. Three of my associates have also heard this amplifier, in my system, and agree with this opinion and evaluation. Since my former "reference" amplifier, the (highly modified) Golden Tube 300B (now in Class B Upper), has previously survived every challenge since 1996, I feel that the Frankenstein must receive an extensive and in-depth examination from me at this time.

Accordingly, I will first discuss my personal amplifier history for the last 25 years or so, and how my choices evolved along with my audio/musical priorities. Then I will detail exactly how the Frankenstein outperforms the countless amplifiers currently available, manufactured today and/or in the past, and at all price points.

Finally, I will attempt to help readers decide whether the Frankenstein is a viable option for them, in either their present system, or one in the planning stage. This is critical, because the Frankenstein, due to its limited power, is definitely not for everyone. However, even though its rated power is nominally less than 10 watts, its unique design makes it compatible with many of the speakers that can be successfully driven by amplifiers such as the Dynaco Stereo 70, Manley Retro/Neo, Quad II and VTL Tiny-Triode (tube amps in the 15 to 30 watt range).

This speaker versatility would normally be technically impossible for a 300B SET amp to accomplish, but the Frankenstein has extraordinary drive capabilities. In fact, I believe it can be accurately described as a difference in kind when compared with the numerous 300B SET amplifiers of the past, which is why I'm giving it this unprecedented degree of focus and attention.

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PART ONE

MY RECENT (1987-2007) AMPLIFIER HISTORY

During the early to middle 1980's, my main amplifier was the Audio Research D-150 (see the Readers Letters within The Reference Amplifiers for more details). It was modified several times, though not extensively, mainly coupling capacitor changes. Eventually, I decided that I wanted mono amplifiers, so I sold the D-150 in 1985/6, and went through numerous mono amplifiers during the next few years (mainly from my retail store). While several of them were excellent, such as the Ray Lumley M-100 and Quad II, at least after modifications, none of them truly satisfied me. It was a highly frustrating process and period in my audio life, because I always felt that I was missing "something". Then, in 1988/9, I finally found what I was looking for...

I had known about the Jadis JA-80 for a few years. It had come in "1st Place" when TAS/HP did a comprehensive amplifier "shootout" (Issues 35/36*), but it was unavailable in Canada at that time, and it also cost a (relative) fortune back then. So I put it on the back burner, but one of my employees later heard it in a New York City audio store, and his enthusiasm finally forced my hand. Fortunately, a local distributor had picked up the line by then, so I ordered in a pair, along with the Wilson Watt II.

*Compare TAS back then, with their honest and no-nonsense comparisons, with the pablum they publish today.

It didn't take long for us to evaluate the JA-80. The Bottom Line- It was the best amplifier that any of us had ever heard, and on virtually every speaker we used. Anyone could hear its obviously superior performance. It was noticeably more natural, transparent and dynamic than any amplifier we could compare it with, including the old standards that I have discussed before. Personally, I felt that I now had the amplifier of my dreams, and there was no way I was going back to the older designs, which I now considered "old fashioned", if not effectively "obsolete" (stereo, circuit boards, Class AB, compromised output transformers, etc). Looking back now, from a 2007 perspective, I feel the JA-80 was near (or at) the pinnacle of what a classic pentode tube amplifier could ultimately achieve, and I knew of no other options at that time.

This "honeymoon" period was just the beginning of my experiences with the Jadis JA-80, because it ended up being my personal reference for the next 8 years (1988-96) or so. None of my many previous amplifiers had such longevity, but my lengthy history with the JA-80 was also very complicated, with many twists and turns, and the most important details of that history are still very relevant today. Let's start first with the most critical modifications that I performed on the Jadis over those years.

The Jadis JA-80 Modifications

I literally performed over 100 modifications on the JA-80, though only a few of them made a truly serious improvement in sonics. When I say "serious", I mean significant enough that any experienced audiophile could easily hear it. The three most important modifications I made back then, and which I still highly recommend today, were:
1. Replacing the coupling capacitors, which I did several times, starting with Wonder Caps and ending with REL Teflons.
2. Converting the amplifier from Pentode into Triode Operation.
3. Placing shunt film capacitors on both the big B+ caps and (critically) the decoupling caps near the input and driver tubes.

I performed many other modifications, though most of them are now long forgotten. They included resistor and feedback changes, shortening the internal wiring and even putting Polk speaker cable from the output transformer to the speaker binding posts. Sadly, none of them gave me the noticeable results I was hoping for at the time, though a good number of them made at least some improvement, which I still very much appreciated, and never reversed.

Bi-Amping and Tri-Amping Adventures

It's also important to note that, during this entire 8 year period, I rarely, if ever, used the JA-80 full-range. I always had subwoofers, and for around two years (1995/6), I even had a dedicated tweeter amplifier: The VTL Tiny Triode...

The VTL Tiny Triode, stock, and even more so when modified, improved on the JA-80's high frequency performance (which was never its strong suit). Even earlier than this, I had heard another amplifier outperform the JA-80, and in more than just this one area. That amplifier was the smaller Jadis JA-30, which was a little faster, cleaner and more immediate than the JA-80. However, the JA-80 was still considerably more dynamic, intense and big sounding (in a natural manner), and I couldn't give all that up for some relatively minor improvements. (In fact, the decision was so easy at the time, that I can't even say it was a real "decision".)

While this was all going on, I also became aware (thanks to that same, now former, employee) of a revolutionary change in (tube) amplifier thinking. It had started, predictably, on the extreme fringes of audio, but was now quickly making ground even in the "mainstream".

The (Re)Emergence of Direct Heated Triode (DHT) Amplifiers

Tube amplifiers using DHT output tubes were very rare in the 1980's but, for some reason, this all quickly changed in the early to mid 1990's. A few though growing number of companies, mainly small startups, were coming out with DHT amplifiers, and most of these were very low-powered Single Ended Triode (SET)* models.

*"Sound Practices", an influential magazine, first published by Joe Roberts in the Summer of 1992, dedicated itself to SET amplifiers and horn speakers.

To fully appreciate how radical this turn of events actually was at the time, and even today, I must now provide a rudimentary history and explanation of these terms...

It all started with the invention of the first vacuum tube in 1906 by Lee De Forest. He originally called this tube an "Audion" (like the audio company of today), but he later called it a "Triode", because it had only three elements (Cathode, Grid and Plate). This name change was necessary at the time, because...

The name "Triode" distinguished it from "Pentode" (and the earlier "Tetrode") tubes, invented 20 years later (1926 by Bernhard Tellegen), which had more than 3 elements ("multi-grid"). Because Pentode tubes could provide more amplifying power, everything else being equal, they eventually became more popular than the "obsolete" Triode tubes. In fact, every tube amplifier I ever saw, heard or read about, that was manufactured from 1950 to 1970, used Pentodes.

Since 1970 (when all tube amplifiers were considered "obsolete" by the general public because of advancements in transistor technology), all of the well-known tube amplifier manufacturers (Audio Research, Conrad Johnson, etc.) used only pentode tubes in their models (such as the 6550, KT88, EL-34, KT-77, 6L6, EL-84 etc).

This brings us to the "Big Question": Why did some audiophiles and manufacturers now want to go back to using the original Triode tubes, which had been considered to be "obsolete", and impractical, for more than 40 years?

Simple: They claimed that the fewer elements in the Triode tubes provided superior sonics in comparison to the more complicated Pentode tubes. It was the "minimalist" audio philosophy in practice, but now even taken into the internals of the actual amplifying device(s). In effect, it was almost like the equivalent of eliminating an entire component in the signal path (such as a linestage). While there was still an obvious and inherent quantitative compromise (loss of wattage), it was more than made up for the qualitative improvement. With the existence and utilization of triodes, there was now even a claim of a new "Hierarchy" of purity and musical accuracy among the tube amplifier universe (in descending order):

5. Standard Pentode Push-Pull (90+% of all the tube amps ever made- such as the Dynaco Stereo 70)
4. Pentode Push-Pull, but rewired into "Triode Operation" (such as the ASL Hurricane)
3. DHT Push-Pull (such as the Altec 1570B)
2. DHT Parallel Single Ended (Not a push-pull, but still more than one output tube- such as the Manley Retro/Neo)
1. Single Ended Triode (just One DHT output tube- such as the Wavelength Cardinal)

However, for many audiophiles, even those with open minds, this DHT Renaissance all sounded "too good to be true" and, sure enough, a profoundly different perspective about DHT (and especially SET) amplifiers was soon made public, and with heat, force and clarity. Thus began one of the most contentious controversies in audio, then and now.

The Arguments and CounterAttack against DHT (and especially SET) Amplifiers

It was inevitable that the manufacturers (and dealers) of the traditional pentode designs (as well as some transistor models and, of course, their friends in the mainstream audio press) would eventually bring up the potential problems with using DHT amplifiers. They were correct in doing so, because the majority of these amplifiers were/are not suitable for most audiophiles. The main problems they pointed out were as follows:

1. Their lack of raw power, especially in the SET models, which made them impractical with most contemporary speakers.
2. Their (mainly) no-feedback designs, which made them sound highly colored with typical speakers, which had highly variable impedances.
3. The output tubes were usually very expensive and/or difficult to find, because many of them were NOS types.
4. The output transformers usually rolled off both of the frequency extremes, because of the lack of feedback and other compromises.
5. Some of the models used very high internal voltages (1,000+) to achieve their power, which the critics claimed was costly, dangerous and inherently unreliable.
6. The higher cost to manufacture, because of the now uneconomical parts cost, in turn due to the low scale of current production.

In effect, the critics reminded audiophiles of the valid reasons why the SET models became "obsolete" in the first place. Further, their points were serious enough to make many careful audiophiles hesitate before pulling the trigger on these designs. As for myself, I didn't have the money at the time to make an investment, but I would have if I did, because of the DHT's theoretical potential (which is almost all that matters to me).

Over time, I eventually became desperate to at least hear any of the finest DHT models, and in a system that was highly revealing. Fortunately, a close friend finally purchased one of the most hyped DHT/SET amplifiers then on the market. Shortly thereafter, this led to what became one of the most important listening sessions in my (our) audio journey, with consequences reaching far beyond DHT amplifiers. I will never forget that day. There were four of us present, and we were all as excited as a kid on Christmas Eve. We all thought our audio lives were going to change, and they did, but not as we expected...

The "Big Shootout"- The Jadis JA-200 Versus the Cary 805

This eventful day was in early Fall 1993, on a Sunday, at the home of Israel Blume, now the owner/designer of Coincident Speaker Technology. However, at that time, Coincident did not yet exist. Also present was Irv Isenberg, the recent purchaser of the Cary 805 amplifiers, who would later start up the Ars Acoustica speaker company (now inactive). An audiophile friend of Israel was also there (the fourth person), but his name is now irrelevant, so I shall respect his privacy.

To set the scene:

Israel's outstanding listening room was in his basement. It was huge, extremely solid, and it even had curved walls to reduce standing waves. His system was also superb: He had the exact same front-end as me, the Forsell Air Reference, VDH Grasshopper and Expressive Technology SU-1, as well as the main speakers, the Wilson WATTs (though modified with much better tweeters than mine). His "subwoofers" were the Tympani IV bass panels, enclosed in a heavy granite stand (I later ended up with these same woofers and stands myself). His Jadis JA-200 amplifiers were modified to the exact same degree as my own JA-80 amplifiers. This was not an accident, since we had previously shared all of our respective modification experiments and results.

It is also critically important to understand our perspective at that time: All four of us were strongly predisposed to prefer the Cary over the Jadis. This was because of the 805's growing reputation, simple design, appearance (outward build quality), and the fact that it had even been further improved with some modifications (which Cary themselves would implement within the next year or so). Our focus, at the time, was on how much of an improvement we would hear with the 805, especially since it only had to drive the small Wilson WATT, and whether we could still live with the Jadis afterwards. Before we could make up our minds though, we first had to hear the Jadis, in this system and this room...

Israel played a variety of excellent recordings, small and large scale. What amazed us was both the incredible improvement he had achieved by replacing the WATT's stock Focal Kevlar tweeter to the Focal Titanium (Irv said "It's like putting a mint in your mouth after smoking a cigar") and the excellent integration of the Tympanis with the WATTs (both of which made me envious). After more than an hour of listening, with growing excitement, we were all dying to hear the Cary amplifiers raise the sonics to an even higher level of performance. So we then changed amplifiers, and warmed them up while having a snack break. After a half-hour or so, with our collective anticipation now unbearable, we agreed it was time to hear them. However, I asked Israel to first play some records that we had NOT heard with the Jadis, just in case we had rushed things.

Israel first played a familiar Mozart chamber music record on the Harmonia Mundi label, which I had remembered from previous visits. This LP was obviously not very dynamically challenging, which was why it was chosen, but it still sounded somewhat veiled and dead to us. Then he put on the Jennifer Warnes "Famous Blue Raincoat" LP, which was highly popular back then. While the voice had natural "body", it was, once again, noticeably veiled and dead sounding. Then he played some orchestral work, the title now forgotten. It was even worse. We all said the same thing: "Something was wrong". There was only one way to find out the truth.

So Israel put the Jadis amplifiers back in the system and played the same records. It only took a few seconds with each LP to hear the huge differences: There was no comparison, the Jadis simply destroyed the 805. Everything became transparent, dynamic and alive again. The differences between the amplifiers were so pronounced, that the Carys almost sounded "defective" (they weren't) by comparison. Needless to say, we were all in shock and, shortly after that, truly depressed (especially after we replayed the 805 for verification). This was because none of us had anticipated anything remotely similar to this outcome. However, all of these surprising experiences, individually and in total, inspired both important positive and negative outcomes, some of them actually life changing...

The Long Term Results and "Lesson" of The Jadis/Cary Shootout

Shortly thereafter, Israel, and then later Irv, started their speaker manufacturing businesses. Both men were highly encouraged by the relative ease of improving the WATT, which had such a big reputation in the audio marketplace and in the audio magazines. Israel went even further, eventually coming out with audio cables and a number of DHT (and now SET) amplifiers.

Meanwhile, Irv, very disappointed with the Cary's performance on the WATT, ended up buying a pair of Jadis JA-80 amps, and then modified them to match my own pair. Later on, he also purchased a pair of Trilogy 958 amplifiers made in England. After comparing the three amplifiers on his flagship speaker, The System Max (which I still use as my own "reference"), he sold both the Jadis and the Cary and kept the Trilogy. Importantly, Irv actually preferred the 805 to the JA-80 on The System Max, which was a much easier load than the WATT, even though their sensitivity was about the same. Later on, I verified Irv's observations with the Cary and Jadis. There is a serious lesson in all of this...

It's obvious that the main reason why the Cary 805 did so poorly compared to the JA-200 on that fateful day was because of the speakers; The Wilson WATT, despite its small size and deceptively innocuous appearance, was (and is) a real killer to drive. While it had relatively high sensitivity, its highly varying impedance, going down to even 2 ohms at one point, made it the worst match imaginable for a SET no-feedback amplifier, such as the Cary 805. Since all 4 of us were SET "novices" at the time, we had no idea of the impossible technical challenge that the Cary was facing.
The Bottom Line- SET amplifiers with no feedback, as stated above, can not handle anything except high-efficiency speakers with a relatively flat impedance, and that "flat impedance" shouldn't be lower than 6 ohms to boot. (This "rule" is oversimplified, so it will be expanded on at the end of this essay.)

As for myself, my life didn't change like Israel or Irv, but my first experience with SET amplifiers was so disastrous, it altered my predisposition 180 degrees; so now I wanted nothing to do with SET amplifiers period, or DHT amps for that matter. As far as I was concerned, SET amplifiers were for audiophiles who were either nostalgic, "deaf" or "theorists". Accordingly, for the next 3 years (1993 to 1996), I avoided them entirely, until an inauspicious pair of SET amplifiers came into my system by "stealth", and amazingly remained there for the next 10 years!

Our Last Fling with Pentode Amps- Tri-Amping

With the "romance" of SET amplifiers over before it even started for us, I, along with Israel Blume, went back to our respective Jadis amps. However, in 1994, we both added the new element of tri-amping. This was because we felt that tri-amping was the only option remaining to us for a serious improvement in amplifier performance.

As mentioned above, we both had the VTL Tiny-Triode amplifiers, which we eventually modified to the Nth degree (mainly capacitor and feedback changes, but we even removed two of the four output tubes). We were both satisfied with the results we were getting with the VTL, but then Israel, in the middle of our Tiny-Triode modification cycle, and just starting up his new speaker business, found himself with a pair of unheralded SET amps, which he had purchased mainly for reasons of "common courtesy". They were the Golden Tube Audio (GTA) 300B Mono Amplifiers.

After confirming that they were also totally hopeless for driving the WATTS "full-range" (and his own speakers by that time), which was obviously no surprise, Israel then decided to try the (otherwise useless) SET amps on the tweeters alone, in a direct comparison with the (then partially) modified VTL amps. To his great shock, he discovered that the GTA 300B amps were actually better! This event, which I did not verify at the time by going to his home to hear them myself, precipitated an all-out modification "escalation" between us. The pattern was always the same...

I would perform increasingly extreme modifications (such as reducing the VTL's output tubes), Israel would exactly copy my mod on his VTL, and then compare it to the Golden Tube. The results (according to Israel) in every single instance: The VTL was "noticeably improved", but the GTA 300B (now also partially modified) was "still better". This cycle went on for almost a year, with growing frustration on my part, as I waited for him to get back to me each time with the news of another failure. Finally, in 1996, Israel, now on his own, and changing the direction of his new speaker company, decided he no longer needed the Golden Tube amps as "references", and I ended up with them. However, I was also "changing direction" myself...

1996- The Year of Transition

So much happened in 1996 (including late 1995 and early 1997), that I have to first provide an overview. Not only did I receive the GTA 300B amps that Fall, but I purchased three pairs of (two-way) speakers from Israel's new speaker company (Coincident). The purchases, in chronological order:

1. Troubadour (Spring 1996)
2. GTA 300B Amps (Fall 1996)
3. Digital Master (Fall 1996)
4. Visionary Reference (1997)

Meanwhile, I also heard the early prototypes of the Ars Acoustica System Max, first in late 1995, and then a dozen or more times in the next 18 months. Importantly, the second (or third) version of the ARS was better than my modified WATTS. Further, I had gone back into the audio retail business (which meant I rarely left my house for the remainder of the year). However, all the critical events that year centered around the Coincident Troubadour, Digital Master and the GTA 300B, because they completely changed the amplifier/speaker paradigm for both me and Israel Blume/Coincident.

It all started with the arrival of the Troubadour. It had an asymmetrical cabinet, with one 7" driver and a tweeter in the center (like a Tannoy Dual-Concentric). It had excellent performance, especially for the money, but more important, it was very easy to drive (unlike the speakers Israel had designed earlier). In fact, Israel informed me that his GTA 300B was doing a decent job amplifying it "full-range". As I was in no position at the time to verify that claim, I used it with the Jadis JA-80 and my subwoofers (with the WATTS and the Tiny Triodes now put aside). Then, in the Fall of 1996, Israel sold me the GTA amps.

As expected, I immediately made the direct comparison between the GTA and the VTL amplifiers on the WATTS tweeter. It didn't take very long for me (or any of my friends) to hear the SETs' superior performance, meaning Israel's previous assessments had been correct. Next, I tried the GTA 300B on the Troubadours full-range. To my surprise, they were a "decent match", as Israel had predicted.

This meant that, for the first time, I was now hearing most of the benefits of SET amplifiers. While the specifics of those "benefits" are described below, the GTA amplifiers, though only slightly modified, were still superior overall to the highly modified JA-80. However, they just couldn't provide the dynamic range necessary for the full realization of most of my favorite recordings, especially in my large listening room. In short- both amplifiers had fatal flaws, but I also couldn't live without their strengths. I was so frustrated, that I eventually went back to the WATTS using both the Jadis and GTA.

Then Israel, hearing my complaints on almost a daily basis, finally came to my rescue. He suggested trying out his latest speaker, the Digital Master. He even modified it to seal the deal. While I didn't like the name, it turned out that this speaker would change my audio life...

The Digital Master looked like a large WATT, with an 8" woofer and a recessed tweeter. They were even better than my modified WATTS in certain ways (image size), but what made them truly special was the fact that they were easier to drive than even the Troubadour. While the nominal sensitivity of the three speakers was very similar, only the Digital Master came "alive" with the Golden Tube. In fact, the dynamic range of the GTA/Digital Master was almost the equal of the Jadis/WATTS. Meaning any differences between them were subtle. Accordingly, with the former dynamic compression no longer continually interfering with my mind and heart, as was the case with the Troubadour, I was now finally able to fully appreciate what a good SET amplifier could accomplish when reproducing music.

Hearing and Appreciating the Advantages of Single Ended Triode Amplifiers

More than any other audio component, it was Single Ended Triode amplifiers in general, and the GTA 300B in particular, that initially brought to my attention (and later convinced me of) the critical role that low-level sounds play in the complete and accurate reproduction of music. It was the SET's unique capabilities that inspired my original conceptions, and later the lengthy descriptions, of both the "sound-floor" and "low-level information".

These essays can still be found in The Reference Components File. I strongly recommend that these essays be read by all visitors to this website, assuming you want to understand "where I'm coming from". However, to highly condense here what I've already written...

It's low-level information that allows the recorded musical performance to sound "unique and human", rather than "generic and mechanical". Once heard and experienced, a music lover can't give up the resulting emotional communication and intimacy. Looking back now at my entire audio "career", I have always preferred components, and not just amplifiers, that better complete the entire musical picture. Further, I've noticed countless other audiophiles reacting in the same manner as myself when given the choice (or not) of hearing this extra information. They may use different terminology, but we're all hearing the same things.

This was also why I had earlier felt that the Jadis JA-80 was better than all the other amplifiers I had heard in the past, such as the finest ARC and CJ models. In fact, that is why I have almost always preferred the better tube electronics; because even with all of their own problems, they still completed the sonic picture noticeably better than any transistor models I could find. However, SET amplifiers took this advantage, or superiority, two giant steps further.

This was first because the GTA 300B's superiority over the Jadis (in information retrieval) was much greater (more noticeable) than the Jadis' own superiority over the other pentode amplifiers. This time it was a difference of kind, rather than a(nother) difference in degree. It was similar to the differences between transistors and tubes, both in noticeability and in my emotional reaction. And there was something else...

Along with the greater amount of musical information, there was now another easily noticeable improvement, which was also of critical importance: All of this musical information was now better organized, so it made more musical sense (it must be noted that music, itself, is the art of organizing tones and sounds). In short, it was both a qualitative and quantitative improvement, with each further enhancing the other (exponentially).

A serious reflection on the implications of this new reality was unavoidable at the time, and I eventually came to the inevitable, but still shocking (to me), conclusion...

The Speaker/Amplifier Paradigm Shift

Not only did the GTA 300B's unique performance capabilities effect, focus and clarify my audio philosophy and priorities, it also changed my practical and/or strategic methodology of how to put together an actual audio system. Please understand that only the most profound audio experiences can actually alter your most fundamental beliefs, but this happened to me (and to my associates).

Prior to the arrival of the GTA 300B (30 years- 1967-96!), I would always choose my favorite speaker first, and then look for the best (usually tube) amplifier I could afford to work with it. This exact same "Rule" is also what I advised to all of my friends and customers during that entire period. However...

The "Speaker-First" Rule had now Reversed itself!

I realized I couldn't live without the unique sonic qualities of the GTA 300B (or an equivalent, top-notch) SET amplifier. Accordingly, any future speaker system also had to be able to be driven by it. If not, it might as well not even exist, no matter what other sonic strengths it possessed. I know this all sounds extreme, but what I had now experienced with the GTA 300B was also "extreme". In short, I couldn't give up all that I had now gained. More importantly, I couldn't think of a realistic scenario that would reverse the new (SET Amplifier-First) Paradigm, because a truly superior speaker, if anything, would reveal/expose even more of the inherent problems with Pentode (and other non-SET) amplifiers. To me, and my associates, this SET Amplifier-First Rule was the only logical* conclusion left to us, based on our actual experiences.

*If all Non-SET amplifiers had extra inherent flaws, and at least some high efficiency speakers had no (offsetting) extra inherent flaws, than the best option had to be a SET/high efficiency speaker combination, because of its unique absence of extra flaws.

Faithful to this new rule, I tried out two more speakers within the next year. First came the earlier promised Visionary Reference from Coincident. This was a floor-standing, two-way speaker with an asymmetrical, heavy-duty cabinet. It utilized very expensive drivers, including a high efficiency (and more expensive) version of the Dynaudio Esotar tweeter, plus their matching (high-efficiency) 8" woofer. The impedance was also benign, being a flat 8 ohms. It seemed to be an excellent match with the GTA 300B "on paper", and it was also in real-life, though I found it a sonic mixed bag.

The Visionary was very neutral, clean and extended in the highs. It was also detailed and cohesive, but I found it also somewhat "analytical" and compressed (at all volume levels). Amazingly, its weaknesses were the Digital Master's strengths (and vice-versa), putting me in a serious dilemma. I couldn't decide which speaker I preferred, both now unsatisfactory, but then came the speakers that solved all of my problems. After more than two years of updates, experiments and trials, Irv Isenberg brought over the supposedly final version of his "masterpiece".

The Ars Acoustica System Max arrived a few months after the Visionary Reference. Looking very similar in design and appearance to a Wilson WATT/Puppy (though built to much higher standards), it out performed the Digital Master in its important strengths, and almost equalled the Visionary Reference in all of its strengths. This speaker system immediately became my "Reference", and it still is, now 10 years later.

1997 to 2001 - Multiple Challengers and Numerous Comparisons

During this period, in which I owned an audio store before closing it and leaving Toronto for Florida, I was fortunate enough to:
1. Extensively modify the Golden Tube Audio 300B and
2. Compare the modified amplifiers to some of the finest amps in the world.

The original modifications were all done by me. These were mainly coupling capacitor changes (ending up with REL Teflons), shortening of internal wires, and power supply enhancements. Later, in 2001, Israel Blume performed a large modification on these amps; with newly positioned inputs and outputs and a new power supply consisting of only film capacitors. This was the last modification, as the amplifiers then went with me to Florida.

Meanwhile, a large number of amplifiers became available for comparisons. Some were through my store, either new or trade-ins, and some were "loaners" from interested parties. Most of these amplifiers were also modified, though not to the degree of the GTA 300B. I can't remember every amplifier we heard, but I do remember well the finest of the bunch, most of which are still in The Reference Amplifier File.

While none of the "contenders" were able to equal the GTA 300B amplifier in its strengths (the ultra-low "sound-floor"), two of them came reasonably close, though the performance gap was still easily noticeable. They also had serious advantages in both raw power and speaker compatibility. We were never able to come to a definitive conclusion as to which of them was better than the other, but both were outstanding amplifiers. They were the:
1. WYTECH LABS TOPAZ 572
2. VIVA AURORA 572

There were other superb amplifiers, almost as good as the above, and usually far less costly. They were also modified. The best of those were, in no particular order:
1. The Manley Labs Retro/Neo 300B (the best of this bunch)
2. The Atma-sphere M60 Mk.II OTL
3. The Altec 1570B/Tutay
4. The VAC PA-90C (TRIODE)
5. The Trilogy 958

The finest stock SET 300B amplifier any of us heard during that period was the Wavelength Cardinal. It had far better build quality and bass than the GTA 300B, though its sound-floor was not quite as low. We never heard a modified version, but the stock passive parts were top notch, so a serious sonic improvement was not very probable.

Amazingly, while all of the above amplifiers were more powerful than the Golden Tube (except the Wavelength Cardinal), they still slightly compromised the dynamic intensity and shading of the music during the soft and medium passages. This is why I don't trust power ratings, on their own, to be an accurate indicator of "dynamics". Finally, I brought both the GTA 300B and the Altec 1570B/Tutay (for my subwoofers) with me to Florida in November 2001.

2002-2007 - Refinements, A New Generation of Challengers and the Final Comparisons

I put together my next audio system during Summer 2002. (It was excellent, but it did not, at first, equal the performance of what I had in Toronto.) During my years in Florida, I've made several important improvements to the GTA 300B. I first changed the output tube from a Svetlana to a KR 300BXLS, which is still the finest 300B I have heard. I later changed the .01uf coupling capacitor to a V-Cap Teflon. These were the two most serious improvements I made. Herbie's tube dampers, an 18" Coincident power cord and Walker SST treatment also enhanced the amp's performance somewhat. In total, the GTA 300B was now noticeably better, in virtually every way, than the amplifier I had used in Toronto. This is also why it still remained my "Reference" until 2007, because the older version may not have held up for that long against the new, even tougher competition.

A series of extraordinary amplifiers became available in the last 7 years. Among the models that most impressed my associates and I are as follows, again in no particular order:

1. Canary Audio CA-339
2. Coincident MP 300B (second version)
3. deHavilland 845
4. Wytech Labs Topaz 211 (monos)
5. Antique Sound Labs Hurricane
6. Antique Sound Labs AQ1009
7. Convergent Audio Technology (CAT) JL-1

In general, these 7 amplifiers offered audiophiles a greater overall combination of effective power, along with musical quality, than those previously available, and even provided better value for the money. However, it was two other amplifiers that effectively ended the long reign of the GTA 300B. Both of them were SET DHT models:

1. Tektron TK50M/Frankenstein (see the lengthy Essay below)
2. Vaic/KR VV52B
(discussed later)

Israel Blume auditioned all of these above mentioned amplifiers, at length, and in his own system, mainly to hear how they worked with his speakers. Blume also had another pair of similarly modified GTA 300B amps for lengthy periods. So while he would be enthusiastic about a recent amplifier discovery, he would also admit to me that it still did not equal the performance of my (and his) GTA 300B reference in its strengths; ultra-low sound-floor, naturalness and lack of an electronic character. However, the arrival of the Tektron/Frankenstein (TF), in the Summer of 2005, finally ended that 10 year victory streak. At first, it was hard for me to believe this unexpected result, but I soon visited Blume, and it didn't take me long to hear for myself the unique qualities of this, literally, one-of-a-kind amplifier.

While the performance of the TF was very similar overall to the GTA 300B (except in the mid-bass, where it was far superior), it was faster and had even less of an electronic sound, or character. Further, not only was its inherent character less audible than any amplifier I had ever heard, the TF almost "sounded" as if nothing was there. The TF also sounded more powerful and dynamic than the GTA, even though, with a single 50 output tube, its nominal rated power was around half of a 300B. Unsurprisingly, I was totally mesmerized by this amplifier, which was why I later spent the time to write a long essay about it, even though the TF didn't really exist as a manufactured component.

The only relevant issue, question and hope, was whether Blume could now actually duplicate the unprecedented performance of the original Tektron/Frankenstein, in a manufactured component, available to the public (and with a 300B output tube). The answer took 18 months to resolve, but it was YES (and even more so). This brings us to the present, and the Second Part of this essay, where I will now describe how the Coincident Frankenstein outperforms all the other amplifiers I've heard.

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PART TWO

AN OVERVIEW AND PERSPECTIVE ON POWER AMPLIFIERS

Before focusing on the specifics of the Frankenstein's performance, I would like to first discuss what the Ideal amplifier is suppose to achieve. The major difficulties to reach this "ideal" are optimizing (perfecting) the three basic and fundamental elements common to every amplifier.
They are:

1. Power/Drive Capability (PDC)
2. Accuracy
3. Completeness

Let us now discuss each of these three elements in detail:

1. Power/Drive Capability (PDC)

This is the easiest capability to understand, and also the easiest amplifier engineering problem to solve "on paper" and in "real-life" (assuming a relatively unlimited budget is available to the designer). By definition:

The greater the PDC of the amplifier, the fewer speakers there will be that compromise the full performance capability of that same amplifier (Elements # 2 and #3). However, the actual level of that "full performance capability", whether excellent or poor, is irrelevant (at this time).

Accordingly, an amplifier which possesses an unlimited amount of PDC, in theory, will drive every speaker equally well. In short, this means that you will always hear this amplifier "at its best". So no speaker, regardless of its sensitivity or difficult load, will compromise this particular amplifier's inherent (best) musical performance.

A PDC Analogy

I would like to provide an analogy to demonstrate a 100% (perfect) PDC score. There are two sprinters, and each of them will run ten 100 meter races. The first race will be on an ideal track, but each subsequent race will have an increasingly difficult "hurdle" to overcome. By the final race (#10), there will even be a sink-hole before the finish line. (I realize this is extreme, but it is necessary to make my point.)

The first sprinter runs a 10.00 on the ideal track, then slows down .50 seconds in each subsequent race. The final (sink-hole) race is so difficult, the sprinter can't even complete it. This performance is "good", but it does NOT receive a 100% score, because this particular sprinter continually slowed down, and even failed once. (This is also the typical performance of an average amplifier.)

The second sprinter runs a 15.00 on the ideal track. However, he also runs a 15.00 in each of the subsequent races, even including the final "sink-hole" 10th. This second sprinter receives an 100% perfect PDC score. The fact that he's much slower, some or even most of the time, compared to the first sprinter, is totally irrelevant. In Conclusion- No "hurdle" was ever able to compromise this sprinter's best performance, and that is all that matters to achieve 100% PDC "perfection".

Obviously, a 100% PDC score is most desirable, especially for those audiophiles who are continually changing speakers, and with no regard to their drive requirements. Do such amplifiers actually exist? I think so. While I am in no position to either confirm or invalidate their claims, there are (and have been) a number of truly heavy-duty amplifiers from Krell, Classe, Boulder, MBL, Levinson, PASS and Rowland that, at least in theory, have the ability to drive any speaker load, and without compromising their best performance.

Finally, there are the two types of "specialist" amplifiers, both of which have tremendous potential power capability, but for only one particular type of speaker. Accordingly, neither of them can ever receive a high (let alone perfect) PDC score.

For example, the famous Mark Levinson ML-2 had stupendous current reserves, allowing it to even drive the ultra-challenging Original Apogee loudspeaker (with a .3 ohm load). However, with a much different speaker load, let's say 16 ohms, the same ML-2 would almost be like a SET amplifier (12.5 watts), because it lacked voltage.

Conversely, there are some tube amplifiers with enormous amounts of voltage reserves (such as many OTL tube models), making them ideal for high impedance loads, but with virtually no current. They would, in turn, be a total disaster with the Apogees, or any speaker with an unusually low impedance. By necessity then, an amplifier with a 100% PDC rating, must have huge amounts of both current and voltage reserves.

2. Accuracy

This element is obviously fundamental to "High-Fidelity", and most working definitions are usually routine, if not self-evident. I dissent here, and this is where I separate myself from "tradition" and "routine". The working definition of "accuracy" that I will use is considerably more restrictive than normal. This is not arbitrary on my part, as will be seen later. Now, under "Ideal" Conditions, as defined above...
My definition of "Accuracy" is:

Doing nothing wrong. "Wrong" is defined broadly as various distortions, added noise, frequency irregularities, phase shifts and (inertial) slurring etc. (Basically, "wrong" means altering, or screwing up, the signal.)

However, it must be emphasized that this newly restricted definition is NOT the same as "Doing everything right"! While the two terms superficially appear to describe the exact same concept, the subtle difference between them is critical. I would like to use another analogy to distinguish them, and also use extremes to discover and explain how an amplifier can be described as 100% accurate.

An "Accuracy" Analogy

There are three students taking an examination. The winner receives the bragging rights of being "The most accurate student". The rules of the examination are based on my definition of "Accuracy" above. The test has 100 questions, of which 50 are in English, and the remainder are in four other languages (Spanish, Russian, Chinese and German).

The first student, the most knowledgeable and hard working in the class, answers all of the questions, and gets 98 of them correct, while getting only two of them wrong.

The second student, a serious rival of the first student, is unfamiliar with the Russian language, so he skips those 10 questions, but then uses the extra time to answer all of the 90 remaining questions correctly.

The third student, a relative slacker, only speaks English. He only answers the questions in English, and with the extra time, he is able to answer all of these 50 questions correctly. Now, which student officially wins the bragging rights of being "the most accurate student"?

The answer, using my definition above, is that it is a Tie between the second and third student. The first student answered the most questions correctly, but he was wrong more often than the other two, and that's all the counts at this point. The second student also answered more questions correctly than the third student, but that is irrelevant, because the third student also did not make a mistake. So officially, both students are now the equivalent of an "100% Accurate amplifier".

Now, to be most extreme, it's true that a fourth student could have answered only one question correctly, then quit, and still won (or tied) the contest, but that is the only possible result consistent with my restricted definition. (Answering no questions would be a disqualification.) Of course, this scenario would be considered highly unfair in real-life. That is irrelevant, and besides, while the first student may have lost this particular battle, the war is not over.

There is still one final Amplifier Element to discuss, but before we go on, let's get back to actual amplifiers.

The relevant audiophile question at this point is: Are there existing amplifiers that excel in both PDC and Accuracy? Once again, I believe the answer is yes. In fact, the exact same amplifiers that were prominently mentioned above as "PDC perfect", are also close to "Accuracy Perfect". This is why, to most audiophiles, they all sound very similar to each other, and some audio critics even claim "they all sound exactly the same".

When you think about it, why shouldn't they "sound all the same"? If they're always at their best and they're also Accurate (not making mistakes), what can actually distinguish them from each other? Well, this is where the third amplifier element of "Completeness" emerges. (And for those sensitive readers still feeling sorry for the first student, his time has now arrived.)

3. Completeness

This element is the most subtle and elusive both to define, and to accomplish. In fact, it's not even individually recognized by many audiophiles. Some even feel it's "imaginary" or worse, a "distortion". This is a tragedy for them, and everyone else in the long run, because ignorance of this element is a near impossible obstacle for any serious audio designer to overcome. My Opinion: No audio component can be truly "Great" without "Completeness".

In reality, "Completeness" is an inherent (and major) part of "Accuracy", but I have long separated them in my mind. It is then only consistent and practical for me to do so for the purpose of this essay. This "separation" is not surgically clean, so there may be sonic parameters in both elements. However, to distinguish these two elements, as I define them, as clearly as possible...

Accuracy pertains only with Errors of Commission

Completeness pertains only with Errors of Omission

Further...

Transistor and Digital Source Components tend to excel in Accuracy, while...

Tube and Analog Source Components tend to excel in Completeness. Also...

Accuracy, by and large, can be measured.

Completeness, by and large, can NOT be measured, at this time.

My main purpose is to relay the increasing importance of "Completeness" as the "missing audio dimension", which many audiophiles are desperately searching for, maybe without even realizing it. For many serious and experienced audiophiles, "completeness" is the determining factor when evaluating the relative, and ultimate, performance of an increasing number of components.

This steady elevation of "completeness" (or other audiophile terms with the same meaning) as a priority, has been an inevitable evolutionary step for audio reproduction. This is because as components become more accurate over time, the last frontier for audiophiles is to optimize the amount of musical information that will pass through these more accurate components. Once again, under Ideal Conditions...
My definition of "Completeness" is:

The Intact Passing of the Complete Audio Signal. Or, in other words: No part of the audio signal (music), even the most subtle, is lost (forever).

For example, and to grossly exaggerate the differences between components to make myself clear:
A poor component will only reproduce "shouting", while
A good component will also reproduce "normal conversation", and
The finest components will even reproduce the "softest whispers".
Using more traditional audio terms: think of "Whispers" as: Decays, harmonics, ambience, dynamic shifts, continual presence and any other soft sounds you can imagine.

However, there may be a problem with classifying "Dynamics". I have placed it within this particular element, because I have found that there is consistently less compression with components if they are are also more "complete", but I can understand someone feeling that it should instead be part of "Accuracy" or both elements.

In practice, based on extensive experiences, for a component to be accurately characterized as Complete, it must have a Low "Sound-Floor". In fact, these two terms and/or concepts are inseparable, because they are either both "there", or "not there". I have already written extensively about the "Sound-Floor" of audio components, including within this essay. I assume by now that the reader is familiar with its definition and its critical importance to the reproduction of music.

Further, if we go back to the earlier "Student Exam Analogy", you will recall that only the first student answered all of the questions. This is the equivalent of being 100% Complete. While he was not 100% accurate in his answers, that is a separate element.

We have now finally reached the point where we will attempt to put these three separate amplifier elements together, in some sort of intelligible whole. If successful, we'll have an accurate perspective of the Frankenstein's performance, and hopefully, we will also be able to better understand and evaluate the performance of other amplifier designs, including some of the most interesting models, past and present.

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PART THREE

THE FRANKENSTEIN'S SUPERIOR PERFORMANCE

A Subjective Description and Evaluation of the Coincident Frankenstein Amplifier

The Frankenstein is a very difficult component to describe. There is a good explanation for this. Some readers (hopefully) will remember a lengthy essay I posted in 2006 (now in My Audio Philosophy), that discussed the words I wished were used more often by audiophiles, both in speech and in thought. They are:
Indescribable, Unpredictable and Surprising.

Those particular words were chosen because I feel they best describe the performance of the absolutely finest components, in both theory and, on extremely rare occasions, in reality. The Coincident Frankenstein is one of those rare occasions of "Reality" confirming the theory. (The most recent previous occasion was the ZYX UNIverse, which is more than a year ago now.) In fact, it's the performance of the ZYX (and the Tektron/Frankenstein) that inspired that essay in the first place.

I feel the best, and most easily understandable, method to describe the Frankenstein, is to directly compare its performance to the "Reference" amplifier it has now replaced; The Golden Tube Audio 300B (GTA). It must be remembered, as posted above (April 2007), that the (highly modified) GTA was the reference for 10 years, and directly (though usually indirectly) outperformed countless amplifiers during that period. We will first focus on the strengths of the GTA, and see how the Frankenstein compares to it, when both of them are "at their best":

The "Sound-Floor"- This is the GTA's "trump card", and its single greatest strength. It simply passed (reproduced) more musical information than any other amplifier I've (or we've) heard. No other amplifier was as "complete" sounding, but this has now changed. The Frankenstein is a little better than the GTA in even this critically important category. While the differences are relatively subtle, the Frankenstein has even greater musical integrity at the softest volume levels, and also captures a little more of the decays, harmonics, textures, space etc. This is small in degree, but still a great achievement, because a new standard has now been set.

Neutrality of Character- This is a repeat of the above. The GTA had the least "character" of any amplifier I've ever heard, but the Frankenstein has even less character, to point where it is literally "indescribable", or, in other words, it "sounds" like "nothing". I think this is partly because of its surprising strength in the next category. The Frankenstein, then, once again sets a new standard in this category.

Cleanness and Purity- The GTA is excellent in this category, comparing with the best tube amplifiers I've ever heard, and at any price, though it was not as good as the finest transistor amplifiers, with their ultra-low distortion. The Frankenstein again outperforms the GTA, and actually competes with the finest transistor amplifiers in this area. I would require a side by side (A/B) to separate them. I certainly know of no other tube amplifier with this level of purity.

"Dynamics"- The GTA equalled (or exceeded) any amplifier I've heard in dynamic shifts, from the softest sound levels to just below "loud". Above that, it couldn't equal the most dynamic amplifiers out there (Jadis, CAT etc). That's very impressive for an 8 watt amplifier, but the Frankenstein takes this outstanding performance to an even higher level. I know this may be hard to believe, but the Frankenstein is actually competitive with the most dynamic amplifier I've ever heard, the Coincident Dragon, which is 10 times more powerful. If anything, it is actually a little more dynamic than the Dragon at very soft levels, which, of course, is the Frankenstein's unique strength. The real surprise (and achievement) is at average to loud levels, where the Frankenstein continually reminds me of the Dragon in its sheer dynamic intensity.

I plan to re-audition the Dragon after I install a new (250K) volume pot, which better matches it with my current system. At that time, I'll come to a more definitive conclusion, which will be posted. At this time, I can say that, other than the Dragon, the Frankenstein is the most dynamic (uncompressed) amplifier I've ever heard.

Speed and Outer Detail- For a tube amplifier, the GTA was one of the fastest I've ever heard, and competitive with any tube amplifier out there, even the better OTLs and the ARC line. Once again though, it couldn't equal the finest transistor amplifiers (Clayton, Spectral etc). Well, the Frankenstein is even competitive with these amplifiers. While I'm not certain that it actually equals them, the differences are now relatively subtle, and not as obvious. In other words, I think it will take another direct, in the room, A/B comparison, to clearly hear any small differences between these amps. Amazingly, this category is actually the relatively weakest part of the Frankenstein's performance. That, alone, is an indicator of its unprecedented overall achievement.

Immediacy- Because of its "Speed", and high overall "Accuracy", the Frankenstein is an exceptionally immediate amplifier. It equals, if not exceeds, any tube amplifier I've ever heard, including the GTA, and may even equal the finest transistor models. Even more important: The combination of this quality, along with its inherent feeling of completeness, gives the Frankenstein more of a gut, direct sense of "Reality" than any amplifier I know.

Imaging/Soundstage- The GTA was also excellent in this general area, but the Frankenstein is still noticeably better. There's better separation and even less homogenization (especially at higher loudness volumes), plus slightly better focus and a larger image size.

Now we will discuss the areas where the GTA was not "at its best". There are two in particular:

Bass Reproduction- The GTA was very good to excellent down to around 80 to 100 Hz. Below that, it's only "good" with a small number of speakers, and simply unlistenable with all the rest. The Frankenstein is noticeably better, in every way, from 80 to 200 Hz, but figuratively "kills" the GTA below 80 Hz. I'll know more about the deeper bass when I listen to the Frankenstein with the Coincident Victory II full-range, but I haven't heard any problems with the bass so far. It's controlled, detailed, impactful, cohesive and natural.

Power/Volume- I don't understand this, but the Frankenstein plays considerably louder than the GTA, even though they're both rated at 8 watts (with the KR300BXLS). This isn't simply a subjective "perception". Everyone hears and experiences it; not only my associates and I, but any non-audiophile, like your neighbor or your wife. It's that obvious. I think it has something to do with the Frankenstein's current delivery, but I'm not certain at this point*. Hopefully, some competent engineer/scientist can eventually explain what we are all hearing. Measurements would help too.

*However, all of the evidence overwhelmingly points to the use of the 6EM7 input/driver tube. This is the same tube that was used in the original Tektron/Frankenstein, and the Coincident Dragon. All three of these amplifiers have outstanding dynamic capabilities. I refuse to believe that this is just a simple "coincidence" (no pun intended).

So, overall...

The Frankenstein is a considerable improvement over the GTA. While they are similar in many ways, the differences all favor the Frankenstein, sometimes subtly and sometimes obviously, even for non-audiophiles. While the GTA is not "blown away" in its strengths, even here there's still enough of a gap in their respective performances to rank a few (theoretical) amplifiers in between them. I feel that a "gap" of this size must be defined as "significant", especially at this high level. As a full-range amplifier though, the Frankenstein is so far superior to the GTA, even with all of its modifications, that any comparison between them would be superfluous, if not cruel.

In conclusion, the Frankenstein noticeably improves on the GTA's previously unprecedented strengths, while dramatically reducing the GTA's blatant (and deal-breaking for many) weaknesses.

Now we must look at other formidable amplifiers, with their own unique advantages and disadvantages.

Other Amplifier Designs Compared to the Frankenstein

When the Frankenstein is performing "at its best", every other known amplifier design, with only one exception, is even less competitive with it than the GTA. However, unlike the GTA, these other amplifiers will now have a theoretical (and usually real) advantage over the Frankenstein when it's not at its best. This is because of the now re-emergence of the Power/Drive Capability (PDC) element. The PDC was irrelevant with the GTA, and thus it was ignored, but it's now extremely relevant.

At this time, for clarification, I feel we should use some actual numbers to better explain the importance of this final element, plus add a new term, which is the mirror image of PDC for speakers. This term is the Power/Drive Requirement (PDR). This is defined by me as: The PDC which is Required by a particular speaker to perform "at its best" (or without compromise).

Let's start with the numbers 1 to 100. This constitutes the total universe of speakers (100%). Further, speakers with a PDR of "1" will be designated as the easiest 1% to drive (such as a typical horn), while those with a PDR of "100" will be the most difficult 1% to drive (such as the notorious Original Apogee). So, as the PDR# rises (from 1 to 100), the speakers will become increasingly difficult to drive. While it's obvious that any amplifier should be able to drive PDR1 speakers (or it would be literally useless), only a few truly heavy-duty amplifiers can drive PDR100 speakers. Accordingly, using this "Rule", an amplifier with a PDC rating of 60 will be able to optimally drive any speaker with a PDR rating of 60 (or below), but it will not be able to optimally drive a speaker with a PDR rating of 61 (or above).

So how do most amplifiers rate on PDC, and what about SET amplifiers, and the Frankenstein in particular? Most amplifiers, push-pull, either tube or transistor, are "at their best" with the majority of either new or used speakers. Even older, lower powered amplifiers, like the famous NAD 3020, will have a PDC of (around) 75. More powerful modern amplifiers, like a typical (100 watt per channel) Musical Fidelity, will have a PDC of 90, or even more. (These PDR numbers are for normal requirements. It's obvious that a huge room, and/or a prediliction for extra loud volume levels, will change/lower these numbers for some audiophiles.)

Unfortunately, SET amplifiers, with their very low power, and lack of feedback, will have a PDC of only between 2 and 30. The GTA is near the bottom of this range, 10 or so (and even then, only above 100 Hz). The Frankenstein has much more drive, so it may even have a PDC of 20 (or higher), but this assessment may be optimistic, and only actual, long-term observations will determine its true PDC.

Keeping this critical PDR factor in mind, let's look at various types of amplifiers, starting with tubes:

DHT/SET "Flea-Power" Models- I don't have much personal experience with these designs but, with one important exception (the Tektron/Frankenstein), I've never heard a model equal the modified GTA in either completeness (though they're close), or in Accuracy (where they're further behind). As for their PDC, it's the very lowest of any amplifier type; at most 5, and usually even less. My associates have more experience with these amplifiers than I do, and they agree with this overall assessment.

DHT/SET "High-Power" Models- Two good examples are the ASL AQ1009 and the Wyetech Topaz 211 Monos. Both are outstanding performers and "references" on this website, but they can't equal the Frankenstein, at its best, in either Accuracy or Completeness. The performance gap between the Frankenstein and these amplifiers is maybe twice* the size of the GTA/Frankenstein gap discussed above. However, these (more powerful) models should have a higher PDC, so they should be "at their best" with more speakers. At this point, I know of no actual comparisons, but in theory...

As the PDR rises, the Frankenstein must lose some of its loudness capability, along with its "Net Fidelity" (Accuracy times Completeness). Inevitably, a point will come when its inherent performance gap will be entirely eliminated. Even worse, it must soon be at a sonic disadvantage to these amplifiers. I don't know where that exact PDR "transfer point" is at this time, or even if it exists. However, if the transfer-point does actually exist, it could be anywhere from between 10 to even 30.

*As mentioned above, there is one important exception to this general evaluation. The Vaic/KR VV52B has greater Net Fidelity than even the GTA 300B, and is the closest known rival to the Frankenstein. So far, I haven't found an independent listener to definitvely compare them. Remember though, the Vaic/KR is considerably more expensive than the Frankenstein.

DHT/Push-Pull Models- Two examples are the Reference Altec/Tutay 1570B and the new Coincident Dragon. The Altec, like most of these designs, is even farther behind in performance to the two DHT/SET amps, but the Dragon is actually competitive (or superior) to them. This type of amplifier will have a much higher PDC than any of those above, coming close to 100. When combining their Net Fidelity with their PDC, these amplifiers become highly desirable and formidable choices for general use, particularly the Dragon, which will be discussed further at a later date.

OTL Models- The best of these, like the Atma-sphere M-60 (and maybe the Transcendent models) are also outstanding performers, particularly in Accuracy. They have the noticeable technical advantage of no output transformer in the signal path, but their more complicated circuits, and extra tubes, have their own sonic disadvantages. Also, their PDC rating, while higher than the SET models, is still relatively low compared to the other designs.

Pentode/Push-Pull Models (PPP)- Such as the Jadis JA-80 or CJ Premier One. These are still excellent performers, especially if modified, but a few steps back from the DHT push-pull models, mainly in completeness (due to a higher sound-floor). Their accuracy is competitive, though again not quite equal to the DHT models (or the OTLs), but their PDC is also usually high (80/90s), an important advantage for many.

There are, of course, a wide variety of different transistor designs to consider:

Traditional Push-Pull- The most popular and prolific amplifier design, by far, ever made, and dominating the electronics world for around 4 decades now. Most do the job well enough, obviously, for the vast majority of listeners, including most audiophiles. The betters models are pretty accurate, with a good PDC, but they almost all fall down in Completeness. The worst are noticeably sterile and analytical, while they best models are relatively natural.

T-Amplifiers- This is the most recent development in transistor amplifiers. I don't have any experience with these designs, but one of my associates does, and he's very impressed. From what he's told me, and what I've read from readers and others, T-Amps are the SET equivalents of transistors, with similar strengths and weaknesses. It's possible that they may (already) provide the highest Net Fidelity for transistors, but their PDC is also the lowest of all the transistor designs.

Hybrids- Meaning those amplifiers with tubes at the input, but still using output transistors. The (now discontinued) Counterpoint line was the most well known of these designs. They are similar to the OTL amplifiers in overall performance, being about as accurate, though not as complete. Their big advantage though is in PDC, which is much higher than any OTL; 90+.

High-Speed Transistor Models (HST)- Such as the Clayton, Halcro and Spectral models. Using my definition above, these are probably the most accurate amplifiers in the world, with unequalled speed, linearity and purity. They are a little more accurate than the Frankenstein but, in relative terms, they are much further behind in Completeness. I'm not sure where the Claytons stand in Completeness, but the Spectral and Halcro are not even competitive with the PPP models listed above, let alone the even better DHT models, and particularly the SET Frankenstein. Their PDC is also high though, almost 100.

Heavy-Duty Transistor Models (HDT)- Such as the big Krells and the MBL. These are the only amplifiers that receive a PDC rating of 100. Better yet, the best designs are almost as accurate as the HST models above, but they have a huge "Achilles Heel". Their Completeness score is among the lowest, on average, of any amplifier type. In effect, compared to the HST models, they trade off both the last bit of accuracy, plus a noticeable amount of completeness, for the last bit of PDC.

These amplifiers can provide a listening experience that can be exciting at first, because of their consistently effortless dynamics at very loud volumes. However, many listeners also hear a (continually present) "mechanical" character in the music, especially at lower volumes, which they find unnatural, monotonous and ultimately boring.

The inescapable reality is that there is an inherent sonic price for using multiple amplifying stages and output devices, and that price is "completeness". For those audiophiles who can't hear (or don't believe in) Completeness, these amplifier designs are basically "Perfect", which is also how they are effectively described by the manufacturers, some of their owners and (far too) many reviewers in the audio press.

"Class A" Transistor Models- There are at least two types here, so this category is less uniform. In fact, there is no universally accepted definition of "Class A". There is first a "standard" version, like the Sugdens. However, some serious purists adamantly deny that the Sugdens are actually "Pure Class A". Then there's a model like the Mark Levinson ML-2, which is very different and considered "the real thing" by everyone. Furthermore, many of the HST and HDT models are also described as "Class A" by their manufacturers, while these claims are disputed by others, including their competitors. It is very confusing.

The standard versions have much of the completeness of the HST models, but lack their extension, speed and they also have less PDC. In effect, they exchange some of the PDC of the "Traditional Push-pull" models for more completeness. Meanwhile, the ML-2 is in a class by itself. It's very similar to the best HST models in completeness. However, it has all the current of the HDT models, but not their voltage capability.

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PART FOUR- CONCLUSION

This essay took me three months of research, writing and editing to complete. This was necessary, because I wanted to make absolutely certain that those who took the time to read this essay, in its entirety, would realize that the final conclusions were logical, consistent and inescapable. Further, I feel that any other conclusion would be ignorant, irrational and disingenuous. Thus, my current advice, based only on our actual experiences, is actually quite simple:

If the Frankenstein is affordable, and it works with your speakers, then it is my first amplifier choice, unconditionally.

To make this even clearer; The use of any other amplifier that I am aware of, at any price, will constitute a sonic compromise with your speakers. So, since I assume that everyone knows the state of their own personal financial resources, in effect...

The only relevant question left is whether the Frankenstein will work with your speakers. Since the Frankenstein is currently available only by direct sale from Coincident (to reduce the selling price), a typical store audition is not possible. At this time, I can offer only limited help and guidance, which is based both on my own experiences, and my associates observations while visiting me:

I feel confident that the Frankenstein will work with:
1. Any speaker now being successfully driven by any SET amplifier of 40 watts or less (2A3, 45, 300B, 211, 572, 845 etc.
2. Any speaker now being driven by any low-power SET amplifier (300B or less), but a little more power (2 to 6 dB) is still required, or desired.
3. Some speakers now being successfully driven by typical low/medium power pentode amplifiers (Dynaco Stereo 70), with the main exceptions being those speakers with a truly difficult load (which requires feedback).

Further, because of my highly positive experiences with the Frankenstein on the (biamped) Ars Acoustica System Max (92 dB), in a large room (5,000 cubic feet) and playing full orchestral music, I feel that the Frankenstein can be used with most speakers with an impedance that is reasonably high, flat and without any sharp phase angles. In short, I feel that the speaker's load is a much more critical factor in reality than its nominal sensitivity*. So, to make this as clear as I can, if the speaker's impedance load is "easy", and any two of the three requirements below are met, the Frankenstein should be viable in your system:

1. 90 dB or higher speaker sensitivity
2. Listening levels are at a natural volume
3. The listening room is 2,400 cubic feet or smaller

Notes- You can't miss any of the requirements in the extreme (84db sensitivity, 110db listening levels or an 8,000+ cubic foot room), unless there's an offset that negates it (ultra-high sensitivity). Also, if only one requirement is met, and the other two are reasonably "close", you should still be viable.

*Recall the Wilson WATT anecdote discussed in "My...History". It had (and has) a relatively high sensitivity, and a truly difficult load, which the Cary 805 was unable to handle, along with every other SET amp we've heard on it.

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PART FIVE

SET-UP, BREAK-IN AND OPTIMIZATION

First, the most important choice is the 300B output tube when it comes to ultimate performance. I started off with the KR 300BXLS, and then switched to the KR 300B "Balloon". Unfortunately, KR raised the price on both tubes and, even worse, the KR tubes are no longer reliable in my opinion. I tried a number of other 300B tubes, all of which were inferior, more or less, except one.

I'm now using the Shuguang Black Treasure 300B-Z, which is reliable and reasonably priced, while matching the overall sonics of the KR tubes. However, I've read really good things about the new Takatsuki 300B (from Japan). It may be the finest 300B available, but it costs a fortune ($ 1,700 for a matched pair!). I will do my best to audition it, but I will have to "save up" for sure.

6EM7 and 5U4 Rectifier

I'm using a pair of NOS RCA 6EM7 tubes. I haven't compared them to other 6EM7 tubes. I did have two different NOS 6EM7 tubes operating at the same time, which caused some slight focus problems, so my only advice is to make absolutely certain that the two 6EM7 tubes are matched. The actual printed brand name is not important, but the insides of the tubes (the guts) are critical. It's the very top (the "roof") of the 6EM7 which is the most easily differentiated part between the types. As long as they're the same, you are safe.

The 5U4 doesn't appear to be critical for performance. Mine are matched, but I'm not sure it means anything. Further, while it has no audio relevance, when the Frankenstein is turned on, in the dark, the 5U4 does a quick, neat "light show". If you blink, you'll miss it.

Further Set-Up and Optimization Advice

I am using Herbie's tube dampers on all three tubes. I found they make a nice improvement on the two signal tubes, but I couldn't hear anything when I used them on the rectifier tubes. Also, I am using the Coincident power cords, which also made a noticeable improvement. Other well designed power cords may make as much, or even a greater, improvement.

As for warm-up, I found it takes around 30 minutes of playing for the amplifiers to perform at their (near) best.

Very Important- Don't forget to try both of the amplifier's outputs (8 and 16 ohms), regardless of the speaker's specifications, or the recommendation from the speaker's designer/manufacturer. You will never know which output sounds "better" (meaning which does less harm with your speaker) without an actual audition. I found that the 16 ohm tap (on the Ars Acoustica) was slightly cleaner, faster, more dynamic and less homogenized, but it also had less "body" (or "fat" depending on the circumstances). Another speaker may have a totally different result.
Bottom Line- You must experiment to be certain which tap is better with your speaker.

Break-In

Even at around 300 hours of play, I still felt (or sensed) that the amplifiers were improving, though it was very subtle at that point. I guess 500 hours finished the process. Owners of these amplifiers shouldn't initially evaluate the performance until it's been operating for at least 24 hours. For a serious evaluation, I would recommend at least 200 hours or more. If a listener is impressed well before this, I can confidently convey the good news that more improvements are still to come.

FULL MUSIC 300B/c OUTPUT TUBE

This is one of the finest 300Bs I've ever heard, and this company actually makes an even better version, the "SE", which I have not yet heard. I originally felt this tube was even superior to the KR 300B tubes that have been my "References" for many years, but I later had some second thoughts. I eventually removed it after hearing the superior Shuguang discussed above.

I have found that there are four potential "downsides" with the Full Music, but I consider only one of them to be serious:

1. They take somewhat more time to warm-up than the KR tubes, or any other output tubes I've had.
2. They are also less sensitive than the KRs, or other 300B tubes I've had. I would guess they are down around 1 to 2 db.
3. I'm concerned that they might have a noticeable high frequency roll-off, at least compared to the KRs.
4. Finally, and I admit that this is pure speculation, or "intuition", on my part, but the 300B/c may sound its best in amplifiers that have a higher plate voltage and/or bias.

Disclosure- I received a small discount when purchasing these tubes. I did not hear them before I purchased them. (12/08)

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PART SIX- THE LATEST (SHINY STAINLESS STEEL) VERSION

In April 2010 I auditioned the latest version of this amplifier and then compared it to the "Original" version that I reviewed now more than 3 years ago (they are still both designated the "MK II"). While I was told the power supply has been changed somewhat, and the actual circuit, size and shape are still exactly the same, the most obvious difference (for most people) will be in the cosmetics. They have gone from "rudimentary" to a shiny stainless steel, almost like chrome, and the three transformers are now hidden. The retail price is also still the same, but this may not last much longer, since the U.S. dollar has dropped quite a bit in value in the last 3 years. As for the sonic differences...

This latest version has several sonic advantages over the original. If I was forced to be ultra succinct, I would simply say it is "more refined", but to be specific, the new version is:
1. A little cleaner, faster and purer.
2. A little more delicate and detailed in the highs.
3. It is also a bit more defined, extended and solid in the bass.
4. The sound-floor, already the lowest I've ever heard in the original, is even a little lower in this version.
5. It is a little quieter, both mechanically and electrically.

If I can broaden the sonic comparisons, though from memory only at this time, and not direct experience, I would make the observation that this new version retains all of the strengths of the original amplifier, while adding more of the unmatched strengths of the fastest and purest transistor models (Spectral, Halcro and Clayton). Alternatively, from a more "musical" perspective; it is "less electronic". In short, this latest version is the closest to "the best of all worlds" that I've yet heard.

Also, while it has no sonic implications, I should mention that this new version runs considerably cooler than the original. You can leave it on for hours and it's still only a little warm to the touch. Further, this change also means that the tubes will have extended life. This may be a serious advantage for some, especially if you are using expensive output tubes (as I am). Also on the "practical side", this new version has an AC ground switch, so any hum can be eliminated without using "cheaters" and/or turning the amplifiers on and off.

This new version does have one practical disadvantage (and I'm not counting the extra time required to clean the shiny surfaces); you lose around 4 dB of gain. For the odd system, this may present a problem, but in most circumstances, including myself, it will be a non issue.

Overall, it's a nice improvement, especially at this very highest level of performance, but I don't want to exaggerate its size, individually or in total. The "breakthrough", in my/our experience, was achieved with the original model. To use a previous analogy, this version is the next page, while the original model was another chapter (and maybe even two chapters) in amplifier performance. However, this is a "page", let alone "chapter", that no other amplifier I've ever heard has reached. This is what makes an otherwise simple refinement into something important.

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PART SEVEN- Teflon Coupling Capacitor Modification and Comparisons

After having the latest version of the Frankenstein amplifier in my system for around 5 years, I decided to make a serious effort to improve on its already outstanding performance, if possible, while simultaneously satisfying my curiosity about the relative ranking of the finest coupling capacitors I've heard (all Teflon). I was initially inspired to start this project by a resourceful reader.

I'm quite excited about sharing the results of my experiments, which should prove helpful to not only the owners of the Frankenstein, but also any other high quality SET amplifier, especially those with no feedback. There were 3 direct comparisons made (plus a "bonus"), and the results may prove to be even revelatory to some serious audiophiles who are willing to think and act "outside the box".

Comparison No. 1 - Solen .47 uf Teflon Vs. ("Original") V-Cap .47 uf Teflon

I could have performed this comparison years ago, but I didn't know that the Frankenstein amplifier even had a coupling capacitor in the first place. This was because of a posting error within the Coincident website's description of the Frankenstein (since corrected). Further, I also didn't have the required V-Cap competitor available as well, so I guess that this delay was an unavoidable "destiny".

In any event, here are the facts: The Frankenstein uses a Solen .47 uf (film and foil) Teflon capacitor to go from the 1st triode to the 2nd triode within its 6EM7 driver tube (an Octal dual-triode tube). The competing V-Cap .47 uf Teflon cap came out of my Jadis JP-80 "phono stage" when it was itself replaced by the latest V-Cap CuTF version of the same capacitor. Both of these capacitors were obviously well broken-in, so that was not a factor in the final results, which are...

The two caps are both outstanding, but the V-Cap is slightly superior. It's a little better at vibrato, which was the biggest difference I heard. It doesn't "stick" as much, almost like the difference between a slide and a series of tiny steps to reach the same destination. Other things are quite similar. Still, the V-Cap is a touch quicker, cleaner (like better cartridge tracking), more refined, delicate and immediate, and it has a lower sound-floor. However, these improvements are all subtle and are definitely no big deal. I would say that most are Level 2 improvements, which means you will probably not even notice them after a minute or so. Also, it must be remembered that I conducted these experiments on an ultra-high resolution system, which means that what I heard may not be as noticeable on even a system that would normally be considered excellent.

So, what are the practical consequences of these results? While the V-Cap is better, I don't believe the mainly subtle improvements are worth making the switch considering the costs involved, so I don't advise it. There is also the matter of break-in, which means the V-Cap will actually sound worse than the Solen for literally hundreds of hours before it is finally optimum. What about those starting from scratch (DIY projects in particular)? In that instance, the V-Cap may be worth it considering the long-run, even with the extra costs and extended break-in, but...

There is another alternative to seriously consider: The latest CuTF V-Cap, which is the finest capacitor I've ever heard. The CuTF is definitely worth moving to, because while the costs are even higher, so is the performance gap. So, at this time, I would advise any potential modifiers to ignore the original V-Cap, if they already have the Solen Teflon in their amplifiers, and going instead directly to the V-Cap CuTF. And this is my same advice considering those "starting from scratch". In short, the extra cost for the CuTF caps is well worth it in every situation.

However, there is even another option, which is somewhat radical and ONLY appropriate and useful for those audiophiles who are Bi-amping. This option requires a detailed explanation so, just below the two pictures, there will be an "Intermission" before the next comparison.

Picture One - Solen .47 uf Teflon Capacitor (The "stock" capacitor that comes with the Frankenstein)

Explanation- This is a picture of the inside of one of my Frankenstein amplifiers, completely stock and without any modifications. Also...

1. The green capacitor is the .47 uf 1000V Solen Teflon Film and Foil, which is in the direct signal path. This is the stock coupling cap that has now been replaced.

2. The baby blue capacitor, just below it, is a 2.2 uf Metallized Solen Teflon cap, which is the de-coupling cap for the Frankenstein. (A film and foil Teflon, 2.2 uf cap, 1000V, if it existed, would be too large to fit inside the amplifier.)

3. Important Note- This is the first time I've ever seen, or even heard of, a quality Teflon capacitor being used in the power supply of a commercial electronic component, at any price, let alone at the cost of the Frankenstein. (Since this was posted, I have found another qualifying component, from Backert Labs, and I assume there must be others as well.)

Solen 47

Picture Two - ("Original") V-Cap .47 uf Teflon Capacitor (The capacitor that came out of the modified Jadis JP-80)

Explanation- This is the inside of the second Frankenstein amplifier, which is a mirror-image version of the above amplifier. As can be seen, nothing has changed except the replacement V-Cap capacitor, which has the same .47 uf value as the stock Solen cap, though it is rated at 600 volts, while the Solen is rated at 1,000 volts. This may be a reason why the two caps sound so similar.

V Cap 47

Intermission

Just as I was about to order two .47 uf CuTF caps (one per channel) for the Frankensteins, I had an audio "epiphany" of sorts. I was finishing up my review of the Coincident Dragon II amplifier, and was discussing the important issue of bi-amping, when I suddenly realized that I didn't need large .47 uf caps for the Frankensteins, since it was only amplifying the Pure Reference monitors, which had very little response below 80 hz. Accordingly, I thought I should first try a .01 uf instead. To make the comparison fair, I would use the exact same type, a .01 uf V-Cap Teflon at 600 volts, and I just happened to have a matched pair of them laying around, previously removed from the Jadis JP-80 (as was the V-Cap .47 uf), and they were completely broken-in.

However, I also realized that my theory, while looking fine on paper, may not work in actual practice. There was a rather obvious potential problem: The deep bass would now be rolled-off with a .01 uf cap, but would it also be noticeable, and cause an audibly lean sound? The actual math was simple and indisputable: with the Frankenstein's 330K loading resistor, the . 47 uf stock cap was down 3 db at around 1 Hz, while the .01 uf cap would be down 3 db at around 48 Hz, and it would also drop another 6 db every octave. That's quite a difference. The big question: Would being down 3 db at 48 hz (and down 9 db at 24 hz), on the monitors alone, be audible? (The subwoofers were completely unaffected.) The only way to find out was to try it out. The results...

Comparison No. 2 - ("Original") V-Cap .47 uf Teflon Vs. ("Original") V-Cap .01 uf Teflon

To get quick and relevant results, for the first few hours I listened intensely only to the monitors by themselves (and thus with my system's subwoofers turned OFF). My goal was simple: If I now heard any type of leanness not noticed before, the experiment would be considered a temporary failure, and I would then go on to Plan B*. Fortunately, there was no (extra) leanness, no matter how hard I tried to expose it with every type of music I had available. The Bottom Line- The Pure Reference Monitors had just as much body as before, and this initial success allowed me to then listen for, and note, any other sonic changes I could observe.

The sonic differences were almost immediately noticeable and, even better, all of them were positive: The sound was slightly cleaner, faster, more relaxed, and less homogenized. It was also a little more more direct, immediate and transparent. The amplifiers sounded like they had a bit more power and control. This latter improvement was very similar to what you hear with better cartridge tracking. All in all, while they were not dramatic, I was obviously very happy with the results, but they were not surprising to me. Why? That answer, which is the most important point of this entire article, will be posted below, after (Bonus) Comparison No. 4.

The next comparison was inevitable. I was initially going to order the latest .47 uf CuTF capacitors, only to decide on trying the V-Cap .01 uf first, and then finding success. So it only made sense to now order a matched pair of CuTF .01 uf caps and then compare them to the original V-Cap .01 uf caps now in the Frankenstein, and that is what I did. One problem though, unlike the V-Caps, the CuTF caps were brand new, which meant an extended** break-in. This was the reason why this article wasn't able to be finished on a timely schedule.

*My "Plan B" was to go to a .02 uf CuTF cap, which would have a -3 db point of 24 Hz, instead of 48 Hz. I felt certain that this larger value would not cause any leanness. In the end of course, Plan B never needed to be implemented.

** The .01 uf CuTF cap arrived with two days of prior break-in on the manufacturer's own "special device". After the installation and gradual improvements, there was a serious performance "jump" somewhere around 220 hours of play, which is the main reason for the delay. I had to wait for it to finally settle down before I was able to come to a conclusion I was confident with.

Picture Three - ("Original") V-Cap .01 uf Teflon Capacitor (This capacitor also came out of the Jadis JP-80)

Explanation- As can be seen, the replacement .01 uf V-Cap capacitor is the exact same type as the .47 uf V-Cap seen above. There is one small difference though in its implementation; The .01 uf cap is soldered directly from one tube pin to a second tube pin, while the .47 uf was soldered from one tube pin to the far side of the short yellow wire seen in the picture, so the signal had to go through one extra solder joint plus the said wire before reaching the second tube pin.

V Cap 01

Comparison No. 3 - ("Original") V-Cap .01 uf Teflon Vs. CuTF .01 uf Teflon

Almost immediately, one could observe that the CuTF was superior to the original V-Cap, though it took something like 400 hours of play to hear the full extent of the improvements. The CuTF was superior in reproducing harmonic content and natural body, musical flow, purity and dynamic contrasts. It was also a little more direct and immediate, with less homogenizaiton, and had a lower sound-floor, with all the associated musical benefits which that provides. This was all deeply satisfying, and adding much to the appreciation of the music, both familiar and unfamiliar. However, it is important to also note that the sonic differences between these two .01 uf signal capacitors were not as noticeable as when I earlier replaced the V-Cap output capacitor, in the Jadis JP-80, with its CuTF equivalent back in 2013 (see The Modification File below for the specific details).

I originally hoped that since this was the final V-Cap to CuTF replacement, there was a good chance that it would also provide the largest sonic difference (which is consistent with the "weakest link" theory). As it turned out, while it was close, this was overly optimistic. However, I soon realized, in hindsight, that I had overlooked two obvious issues prior to the actual comparisons:

1. The .01 uf CuTF replacement only effected the Frankenstein (and the monitors), while the earlier JP-80 CuTF cap replacement effected the entire system full-range.

2. The tiny .01 uf V-Cap in the Frankenstein had far fewer inherent sonic "deficencies" when compared to the (200 times!) larger 2 uf V-Cap replaced earlier in the Jadis. Thus the room for any further sonic improvements would be much smaller.

There were other observations also worth reporting:

In general, the above mentioned sonic improvements were most easily noticeable only with really good recordings, especially heard late at night. In other words, there was very little difference (improvement) early in the evening and/or on (below) average recordings. In fact, the two capacitors sounded almost the same on poor recordings, no matter what the hour, and this isn't the first time I've experienced something like this. So, what does this all mean and are there any explanations that make consistent sense?

I have two theories that may explain these observations:

1. The incoming AC is now most likely the limiting factor (the weak link) in my current system. This explanation seems particularly appropriate because it would fully explain the exceptions observed during late night listening sessions.

There is also the second issue concerning the surprising lack of improvement in reproducing mediocre recordings, which requires another theory.

2. It is possible, if not probable, that these mediocre recordings are missing the type and amount of musical information which would allow a listener to hear any differences once an audio system reaches a certain (high) level of performance. This requires further explaining...

I've long argued (along with others) that the finer the audio system, the easier it is to hear the sonic differences between recordings (and also other components, cables etc). This only makes sense, since the better the system, the less "masking" of the recording, thus allowing its true individuality to be heard. While I am still convinced that this theory is true in general, my most recent experiences, while confirming it, must now also add a condition (or "qualifier") to it as well.

The condition is this: At a certain point in a system's development, it is eventually the recording itself which may become the limiting, weak-link factor. Accordingly, any further system improvements will result in negligible, or even no, audible improvements with mediocre and/or poor recordings. In other words, the better the system, meaning the closer it is to "perfection", the better (or more challenging) the recording must be to separate it from "perfection". (I plan to discuss this important issue in further depth sometime in the future.)

Picture Four - CuTF .01 uf Teflon Capacitor

Explanation- This .01 uf CuTF cap is a direct replacement for the .01 uf V-Cap capacitor seen just above. They are also both soldered to the exact same tube pins.

CuTF 01

(Bonus) Comparison No. 4 - ("Original") V-Cap .01 uf Teflon Bypassing Solen 2.2 uf Metallized Teflon Decoupling Cap

There was one final experiment that looked very promising. I would use the .01 uf V-Cap, which had been removed (and replaced by the CuTF .01) during the last experiment and was now available. I soldered the V-Cap .01 uf in parallel with the 2.2 uf Solen Teflon (blue) capacitor seen in all the above pictures. These two caps were not in the direct signal path, but based on my earlier experiences, I still felt the .01 could "speed up" the amplifier and even allow a little more information to be captured. That was the theory.

In practice, it didn't work out as I had hoped. I heard absolutely no improvement, even subtle. Worse, I even sensed a possible compromise of the image focus. In the end, I removed the .01 cap and this time heard no downsides and maybe even a slight improvement, which verified my original assessment. So, this was the proverbial "bridge too far". However, I'm still glad I made this experiment, since it now rules out that particular avenue for future improvements. You can learn from failures as well as successes when modifying components.

Conclusions

The most specific news from the above results is this: The Coincident Frankenstein amplifier (all versions) can be improved by changing its coupling capacitor. Based on our findings, I only recommend using the V-Cap CuTF caps as the direct replacement. Considering the initial cost of the Frankenstein, and the sonic improvements gained with the CuTF, the cost/investment is well worth it. I also believe that the "original" V-Cap, or any other capacitor for that matter, is not worth using at this time. So, it's a CuTF capacitor or nothing. I can't be clearer than that. However, this news is not the most important point (or story) of this article. What is? The answer to that question requires a quick and concise summary of the three coupling capacitor comparisons above:

1. Solen .47 (uf) vs. V-Cap .47 - Some subtle improvements when using the V-Cap, though only after 500 hours of play. Not worth the investment in my opinion.

2. V-Cap .47 vs. V-Cap .01 - Easily noticeable improvements in many areas with the .01, plus the amplifiers even sounded more powerful and "secure". Not a "dramatic" change, but still quite important.

3. V-Cap .01 vs. CuTF .01 - Easily noticeable improvements with the CuTF in many important areas of music reproduction (after 400 hours of play). While also not dramatic, a "deeply satisfying" change.

In the end, there are only two choices:

A. CuTF .47 uf - Which will provide all of the improvements from Comparison No. 1 and (conditionally) No. 3 as well, but none from No. 2. The cost is $ 420/pair.

B. CuTF .01 uf - Which will provide all of the improvements from all three comparisons. The cost is $ 110/pair.

The ultimate choice between them totally depends on how the Frankenstein amplifiers are being utilized. If the Frankenstein is being used with a full-range speaker, which will be the case in the vast majority of systems, then the .47 uf is the only choice. However, if the Frankenstein is being used on the monitors of a bi-amped system with (sub)woofers (such as mine), then the .01 uf is the obvious choice.

There is also one exception or outlier to the above: The .01 uf (or a .02 uf if necessary) can also be used in the Frankenstein with a system based on a "mini-monitor" type speaker (like the famous Rogers LS3/5A), with its typical severe bass roll-off. This is because the .01's own bass roll-off will then be effectively masked, while all of its sonic advantages will still remain. And this finally brings us to the point or "big picture"...

The True "Bottom Line" and Advice of this Article

The "news" that the Frankenstein amps can be improved with a CuTF coupling cap is not that important, since this was already implied two years ago, when I first reviewed the CuTF capacitors in a different context. Instead, the real news, the real point and the most critical focus of this article, for all serious audiophiles, is the important and unique sonic benefits of using the .01 uf CuTF as a coupling capacitor, if possible. Not only in the Frankenstein, but in ANY amps, usually a SET, that do not use feedback.

I first need to be clear: The CuTF .01 uf is the closest thing to a "direct-connection" that I'm aware of at this time. In fact, the .01 even has some technical and (consequently) sonic advantages over a (theoretical) direct-connection! (The claim of "sonic advantages" may appear impossible, since how can anything be better than "nothing", but please bear with me as I will make this argument below.) Accordingly, the primary goal now should be to find a method to fully utilize the CuTF .01 uf. To do so, and to understand why, means we will now have to take another quick leap back and again summarize some previous findings, this time focusing on the Coincident Dragon Mk. II amplifiers and the related and critical subject of bi-amping. The entire Dragon II Review can be boiled down to this:

The Dragon II was an improvement on the original model (no surprise). However, bi-amping was proved, once again, to be the only method to fully maximize all the capabilities of the Pure Reference Extreme. No one amplifier, at any price, could equal the combined performance of the Frankenstein and Dragon, due to inherent and unavoidable technical factors. In other words, any amplifier driving the midrange/highs will be noticeably compromised if it is also simultaneously driving the bass (woofers), and you do not have to be an experienced audiophile to observe the obvious sonic degradations. Ergo, everything else being equal, which is the only fair method of comparison, a speaker that is bi-amped will always be superior to a speaker that is not bi-amped. That, though, is only half the equation. The CuTF .01 uf is the second half of the equation...

The .01 uf CuTF can only be heard "at its best" with a non-feedback amplifier, which will usually be a single-ended-triode (SET) model (such as the Frankenstein and hundreds of others as well). Besides its inherently outstanding performance, the .01 CuTF offers these extra sonic advantages, over even a direct-connection, when it's "at its best" (as promised above);

1. The .01 will roll-off the lower bass frequencies, which means the amplifier will then waste less of its power reserves, thus providing more dynamic headroom, separation and control, plus less distortion on peaks.
2. The amplifier will also have less intermodulation distortion (which is highly irritating), because there will now be less bass energy to modulate the higher frequencies.
3. Even the speaker drivers themselves will produce less distortion, independently of the above, because they, in turn, will no longer be hopelessly attempting to reproduce the lower bass frequencies. (Needless to say, only "SET-Friendly" speakers qualify in this situation, but that is an obvious given.)

In short, what we now have is a "Win-Win-Win" scenario, which is the rarest and most welcome opportunity for a serious audiophile, whom is otherwise almost always burdened by compromised choices. It almost sounds "too good to be true", but this time it is true. So let's now summarize everything as concisely as possible:

1. When everything else is equal, a bi-amplified speaker is always superior in performance to a speaker that is not bi-amped, mainly due to the unavoidable sonic compromises in the midrange and highs when using only one amplifier, no matter what its cost and quality.

2. The .01 uf CuTF coupling capacitor, used in a non-feedback midrange/high frequency amplifier, in a bi-amped system, will provide unprecedented performance; plus greater headroom, separation and control; and less distortion from both the amplifier and the speaker drivers themselves.

The Resulting "Strategy"

The "Bottom Line", and my "Advice", is acutely obvious, singular and consistent with the above observations: Serious audiophiles should search for "SET-Friendly" speakers which can also be bi-amplified. It's that simple and straightforward.

The speakers do not have to be expensive to work, and neither do the amplifiers. This "Bi-amp/SET Strategy (BSS)" is not some sort of temporary, expedient measure to buy time until money is available to purchase something "really good". This method is for the indefinite long-term. (I've been using it myself, successfully, for almost 20 years now.) It is also important to note that this strategy does not conflict with, or attempt to break, the laws and limits of acoustics and physics*. In fact, it may even be unique in actually accepting and surrendering to these same laws, unlike almost every other system approach I've seen, from every source imaginable (magazines, websites, reviewers, manufacturers etc), since I became an audiophile almost 50 years ago.

In effect, this article is an argument for a greater "division of labor" in audio. Think: The finest audio systems have long used separate components; phono stage, line stage and (mono) power amplifiers. These separate components constitute a successful "division of labor". The "BSS" is simply taking this long proven concept to the next logical level. One speaker driver doesn't usually attempt to cover the full-frequency range, because of the unavoidable limits of acoustics and physics. I argue that there are similar limits which also apply to amplifiers. Serious audiophiles must accept these limits and then devise a plan to work with them. The BSS is just such a plan, and not simply a "theory", because it works, and works well. I know this for a fact, based on the performance of my own system and how it has positively effected such a wide variety of experienced and critical listeners.

Even better, the cost is not prohibitive. In fact, money and time are even saved by avoiding the usual audiophile chase for the technically impossible. My argument is simple: Bi-amping has inherent technical and sonic advantages because of "the division of labor" principle, and a SET amplifier's own inherent technical and sonic advantages just happen to perfectly match the requirements of this particular division of labor. How? The .01 uf CuTF effectively converts a stock SET amp into a midrange/highs dedicated SET amp, while also improving its inherent performance. To be clear, all non-feedback amplifiers offer this same option, and not just the Coincident Frankenstein, which I only used as an example. However...

Most audiophiles are not able to go to a Bi-amp/SET system in one move. There may have to be steps, so what should be the first step? Easy Answer: The purchase of a SET-Friendly speaker that can be bi-amplified, even if the current system is incapable of bi-amplification. Later on, based on the particular circumstances, numerous options will become available, and almost all of them will offer large sonic rewards for a reasonable investment. This is in stark contrast to making large investments for modest improvements, which is the typical result when an audiophile follows the recommendations and advice of commercial reviewers and magazines. Many audiophiles have an aversion to bi-amping (let alone SETs) because of the greater complexity, but the BSS can be accomplished in stages, though obviously only with first having a SET-Friendly speaker that can be bi-amped.

*Example- Why attempt to get a 5" driver to reproduce any deep bass frequencies when it will inevitably fail in this impossible quest? Worse, there's always a sonic price to pay when components attempt to go beyond their inherent capabilities, and then fail.

Some Final Words

Within this article, I deliberately avoided using the word "dramatic" when describing the results of a single experiment/comparison, and I never did. However, when you combine all of the sonic benefits when using the CuTF .01 in a good SET amplifier (as described in the three comparisons), the word "dramatic" can finally be used with both justification and confidence. That is the reason why I felt compelled to share this "good news" with other audiophiles. Finally, it took me almost 3 decades of experiments to evolve into the Bi-amp/SET Strategy, and another 2 decades proving it to my, and my friends', satisfaction. And now these entire 5 decades of my audio life have been condensed into an article that takes less than an hour to read.

Records Used for Evaluation:

A large number of records were played during the evaluation period, but those below were used the most often:

Albeniz- Suite Espagnola- Decca/London- Space, harmonics, separation, transparency, immediacy, vibrato, sound-floor, dynamics, musical flow.

Bach- Mass in B Minor -Richter- Archive- Voice and word intelligibility, separation, musical flow, detail, space, decays. (An average sounding album, but I am extremely familiar with it.)

Vangelis- China- Polydor- Space, size, separation, vibrato, ultra-challenging dynamics. (An excellent LP to "stress" an amplifier or system, while still providing some subtleties.)

Relevant Links:

The Modification File (Passive Parts)

VH Audio (Home of V-Caps & Source of CuTF Capacitors)

My Audio System

Coincident Speaker Technology (Frankenstein amplifiers/Pure Reference Extreme Speakers)

OCTOBER 2005 ESSAY ON

THE ORIGINAL "FRANKENSTEIN" AMPLIFIER

I spent a lot of time in Toronto listening to the latest "experiments" of Israel Blume, who owns and operates Coincident Speaker Technology. I was a dealer (1996-2001) of his when I had an audio store in Toronto, and he's also a long-time friend of mine. He had told me beforehand that he recently had some interesting experiences, so I even delayed my trip for a few weeks until he had everything working at its best (his turntable had developed a bearing problem that was eventually repaired). I'm happy I waited, because I had one of the most important and exciting experiences I've ever had in audio. Since this can't be conveyed and written about in a paragraph or two, I'm going to break all of this up into sections.

A Short Prologue

Veteran readers will recall that around a year ago, I also visited Blume and made a number of amplifier comparisons. We had revelatory results (for us); the relatively profound differences between amplifiers using typical Pentode output tubes compared with those using Direct Heated Triodes (DHT)*. The "revelatory results": Only the direct heated triodes (300Bs in this instance) were able to accurately reveal the inherent sonic differences of two special recordings. These same sonic differences were also demonstrated (and their existence further confirmed) to me, and an associate, when we later made some comparisons between speaker cables. Those results- One speaker cable was superior with pentode tubes, while the other was superior with DHT tubes.

(*The respective amplifiers were the Stromberg-Carlsons AP-55, highly modified, and the most recent version of the Coincident 300B monos. You can still read about that actual comparison here.)

The inescapable conclusion for me (and my "associates") was simple; With possibly two exceptions*, I am now convinced that any serious audio system must use an amplifier with DHT tubes, either single-ended or push-pull, if that audiophile wants to achieve the finest musical reproduction available today.

(*The only two "possible exceptions" I'm aware of are the Convergent Audio Technology (CAT) amplifier family, and the brilliantly designed AudioPax Model 88.)

And now these most recent experiences will take us one more rather large step down this DHT road. In short- My focus here will once again be on amplifiers-specifically Low-Wattage, Single Ended Triode (SET) amplifiers, but this time using only ONE (DHT) output tube.

A New Experience!?

What was different this time, in comparison to a year ago, was that Blume was now claiming he had discovered a SET amplifier, with less than 5 watts (!), that was actually able to amplify his (multi) dynamic-driver, Total Victory II speakers, full-range, and with "virtually no compromises". I felt this laudable goal was literally "impossible" to achieve at this time, because...

I/we had already heard numerous 8 watt (300B) amplifiers fail when trying to satisfingly amplify a truly full-range, dynamic speaker, in contrast to an ultra-high-efficiency Horn Speaker, which the SET amps were actually designed for. Please keep in mind, tweeters and midrange drivers are one thing to amplify with only a few watts, while woofers are very different, especially four 8" woofers per speaker. What about an amplifier using an 845, 572 or an 811/211A DHT output tube? Yes, it's been done. I've heard it myself more than once, but never a SET 300B, let alone the even rarer, lower powered 2A3, 45 or 50 DHT output tubes.

Mind you, when these (under 10 watt) tubes are competently used in parallel, like the Manley Neo/Retro, or even better push-pull, like the Canary CA-339, there's no serious power/control problems, but...

In my/our experience, low-powered SET amps, at best*, can only be used for the mid/upper frequencies when amplifying dynamic speakers (like my own speakers), with a more powerful, and less pure, DHT amplifier being relegated for the woofers (also like my own speakers). But Blume stated that a separate woofer amplifier was "no longer necessary", and so I visited him to verify, or more likely disprove, his unprecedented claim. I even delayed my trip so he wouldn't have any "excuses" to fall back on.

(* I must point out that the excellent, though pricey, Wavelength Cardinal was the least compromised, low-powered, SET amplifier any of us has heard in the past when it came to reproducing the bass.)

So What Happened?

This 4 Watt amplifier did it! It drove the Total Victory in a manner I hadn't heard before, and I have heard this speaker with a variety of superb amplifiers, including Coincident's own (parallel) 300B models. The speed, purity, detail and neutrality were simply incredible. While there were other changes in Blume's system, the speakers were exactly the same. More important, I've never heard one amplifier do what this amplifier did in totality. It sounded, and I'm not exaggerating, like a combination of the finest 300B amplifier with the most advanced transistor amplifiers, like those from Spectral (the best of all the commercially available transistor amplifiers that I've heard in controlled conditions-though I doubt I could actually live with it for more than a day).

In short- This amplifier had the strengths of the Spectral; speed, detail, neutrality, quietness, as well as the relaxed and disarming naturalness, inner detail and low-level musical information you both hear and sense with the finest SET amps. This was a new experience for me (as well as for Blume and other listeners). If I had to describe the sound in terms of what I've heard in the past, I would say it was very similar to the Martin Logan CLS at its best, but without the CLS's frustrating phase problems, which are a cause of its mediocre imaging, and the CLS's noticeable lack of bass as well as its thinning of harmonics and sense of space, which can make it sound "analytical" at times. (The CLS still scores itself in overall cohesiveness, with its single driver advantage, and its ultimate speed below 1 Khz.)

I have an even higher compliment, and something I've never claimed, or even thought of, before; The sound actually reminded me of the best Stax heaphones, when powered by their own dedicated tube amplifier. I've just never heard anything, in a live room, sound so neutral and detailed at the same time. However, it also reminded me of the Stax in a less flattering light, so (you guessed it) I did have at least one problem with what I heard...

On to "The Bass"

I still felt the overall sound should have had more "weight" to it. This was most obvious to me on certain orchestral records with deep organ notes etc., but it was also present, though to a less noticeable degree, on some other material. Surprisingly, it didn't bother Blume himself*, who is more of a "bass freak" at heart than I am, but he hasn't recently lived with a good subwoofer, while I have, and we mustn't forget he's "living in the forest", while I'm not. It also didn't seem to bother most of his other listeners, even those with a lot of experience, though not MY experience (meant factually, not egotistically).

Arguably even more important, was another unexpected result that occurred when I decided to go "all the way" and give these amplifiers my personal "acid test" for bass, so...

I asked Blume to play two of the most demanding orchestral LPs that I'm aware of when it comes to challenging subwoofers. These two LPs are the original Mobile Fidelity UHQR versions of The Planets (Saturn) and The Pines of Rome (Catacombs). Some veteran readers may recall that I previously reported that these two records were actually able to expose the limitations of the excellent Entec Subwoofers, even including two pairs of the largest and most powerful models they ever made, the (3-woofer) SW-2. The Entecs produced only distorted sounds during the Mobiles' thunderous organ passages. This was not subtle. In fact, it was so bad, I couldn't even play those records with the Entecs in the system, not only for the sheer ugliness of the indescribable noises, but for fear that the Entecs would be damaged. So what about these SET amps and the Total Victory IIs with the same two records...

To my utter shock, they played them well, with no loss of control at any time, and the volume was "normal". Now don't get me wrong. I've heard both of these passages with more force, authority and weight, but never with more harmonic detail, cohesion and control. This is a singular and indisputable achievement. It is what has excited me more than anything else, because it is, to my mind, a true and real "breakthrough" in audio, meaning I believe there is (or may/will be) another alternative for audiophiles who are unhappy with the current choices offered to them. Let me explain this, because it is very important, critically important in fact...

"A Breakthrough" = New Alternative

The main reason why I'm so excited at these results, is because there is now a new, potential, amplifier/speaker "Alternative" available to audiophiles: Low-powered SET and full-range dynamic speakers. In the past, SET amps, of under 10 watts, were only compatible in two speaker scenarios;
1. High-efficiency horns, though not usually full-range (such as the Avantegarde and Acapella modern horn lines)
2. High-efficiency dynamic speakers, though only in the midrange and high frequencies, such as my own speaker (Ars Acoustica System Max).

Audiophiles who avoided horns and subwoofers, for whatever reasons, couldn't use the best SET amplifiers, unless they didn't mind frustratingly low-volumes, along with other serious sonic compromises. What I/we heard has changed that old paradigm. This leads us to the next topic...

Good News/Bad News/Good News!

The "good news", and the basis of this entire essay, is that a 4 Watt SET amplifier now exists that can drive a full-range dynamic speaker. The "bad news", as this is written, is that it is not yet commercially available, and may never be. I'm now going to describe this amplifier to you, in detail, so you'll know what I'm talking about. Since it is, in effect, an unexpected, fortuitous combination of chassis, design and passive parts, I've named this the "Frankenstein" amplifier. Nothing else fits, or is fair, to my mind.

This amplifier innocently started out its "life" as the Tektron TK50M, a mono amp with a type 50 output tube and a rating of 3.5 watts per channel. It is still currently available from the North American distributor; Robyatt Audio Products. This amplifier can also use a 300B, 2A3 or 45 output tube, all with "the flick of a switch", making it very versatile. The original owner, however, was evidently unsatisfied with the "stock" performance of the Tektron, so he sent it to Cyrus Brenneman Audio, for what would normally be described as a "modification". Fortuitously, it turned out to be much more than that!
(Note- Both of these audio companies have websites.)

In fact, before the emergence of this amplifier, I had barely heard of Cyrus Brenneman, but if I have to single out one person who deserves "the lion's share" of the credit for the existence and performance of this extraordinary and unprecedented amplifier, it goes to Brenneman, who must be, by any standard, highly talented. (It may also be strangely true that, like Chesky and some of their finest LPs, Brenneman himself isn't even aware of how actually good his "own" amplifier performs.)

As alluded to above, Brenneman performed a complete "makeover" of the Tektron, to the extreme point where it could no longer even be accurately called a "Tektron". The basic circuit was dramatically changed and the output and power transformers were both replaced. All that basically remained of the original Tektron amp was its attractive wood chassis, output and rectifier tubes and the remaining tube socket. The amplifier was then sent back to its owner, who still found it not entirely compatible with his new speakers. So he later sold it to Israel Blume, after advertising it on Audiogon. Now it was Blume's turn to improve the amplifier.

Blume is not an Electrical Engineer or a circuit designer, or even a technician for that matter, but he does have extensive experience with standard modifications, particularly replacing passive parts (capacitors, resistors, wires, connectors etc.) with superior versions, and also increasing the size of the stock power supply, if possible. I know of his skills and knowledge first hand, since he helped me with some of my early modifications of more than 20 years ago now, and he even performed an extensive and difficult modification of my Golden Tube 300B mono amplifiers back in 2001, just before I left Toronto for sunny (and hurricane prone) Florida.

As shocked and impressed as Blume was with the Tektron turned "Frankenstein" amp, with all the Brenneman alterations, he replaced every passive part he could, and then augmented the power supply, while also converting every electrolytic capacitor to a film type. He felt the overall change was "significant". It was at this point that I heard these amplifiers myself in middle/late August. This now brings us to the final (second) "Good News!", seen in the title above...

Blume, strongly moved by the unexpected performance of this amp, has informed me that he is now on a "mission" to build an amplifier that is even better than the "Frankenstein" (which he claims he has even further improved since I heard it more than two months ago now). This new amplifier will be 300B based, with self-biasing, using the same high-quality passive parts currently utilized in the Frankenstein.

The circuit will be a virtual replication of the Frankenstein, with the main exception of the different 300B output tube requirements. He expects to get a prototype pair sometime in December 2005. To say I'm excited is a gross understatement. I've wanted to replace my Golden Tube 300B amps for years, but everything I've heard until now have had even more problems than they've solved. Based on what I've already heard, and what Blume told me he would further improve (since the new amp has more internal space), this is the most promising amplifier I can imagine at this time.

The only issue left is the price of this new amplifier. Blume doesn't have an exact price yet, but he promised me that it would be "substantially" less than $ 10,000 for a pair of them. Based on my experience with his use of words, I interpret his nebulous expression to mean around $ 6,000 a pair, or maybe even lower than that. Considering how he described the manner in which the amplifiers would be built, and the high quality of the parts that will be used (such as V-Cap Teflons), which would also eliminate the need for ANY modifications, they should be an excellent value. Now everything depends on whether the actual performance of these amps matches "the promise".

But there's still more to "the big picture"...

Amplifiers and Speakers-The Cruel and Unavoidable Choice

It's been my/our experience that, in virtually every instance, when you compare amplifiers using speakers that don't require huge amounts of current and/or voltage to drive them, the lower powered and/or simpler designs (of equal build quality) will sound superior; meaning noticeably more natural and less electronic. Within this amplifier hierarchy then; the large solid-state amplifiers will sound the worst (while having the greatest speaker versatility) while low-powered SET amplifiers will sound the best (while having the least speaker versatility).

This means there is an unmistakable general "formula" or "rule" to all of this: The inverse relationship between the amplifier's speaker drive capability and its inherent sonic quality. In other words: The more speakers an amplifier can drive without being compromised, the more compromised are its inherent sonics, everything else being equal.

The sonic price for greater speaker accommodation is greater signal degradation. It's that simple.

It's like the difference between an all-terrain vehicle and a racing car. Sure, you can always get from any Point A to any Point B with the all-terrain vehicle, but it's no contest when the two designs are on a smooth and straight highway. To complete this analogy- This new SET amplifier is, in effect, both "faster" and somewhat more "road worthy" than any previous "racing car" I've heard in the past. This inevitably brings us to the critical importance of "the road", meaning the speakers themselves. This is something I feel I haven't stressed enough, due to my current focus on the "Frankenstein" amps, because it's they that are "new".

Don't Overlook the Speaker part of the Equation

When we put the focus back on speakers, I now come to this general perspective: Speakers with "normal" loads, which are the vast majority of speakers now available, are still viable, since some of them possess a sonic advantage(s) over the finest of the "easy-load" speakers, but they will also have the distinct (and unavoidable) disadvantage of requiring a "second-rate" (or worse) signal to drive them; either in part (as in the case of my speakers) or in whole (any speaker requiring large/huge amounts of current and voltage). From another viewpoint- Any speaker without an easy load, and also without any inherent sonic advantage, is, by definition, "second-rate", since it must use inferior electronics without any sonic offset in its favor. It certainly can NEVER be "state of the art". This brings us to the specifics...

These new SET amps are only a "breakthrough" because there exists at least one currently available speaker that can take advantage of their FULL capabilities. At this point, I've only heard them with the Coincident Total Victory II (TVII). When I discussed in detail, and "Referenced", the TVII a year ago, I mentioned the practical advantage of its easier drive capability, but I didn't fully realize (and appreciate) its critical sonic importance (advantage) until now, and neither did anyone else. This is because the Frankenstein amplifier was an unknown entity at that time.

If I had to write-up the TVII again, I would now stress that their ultra-easy drive capability gives them a sonic "head start" over every other speaker that doesn't share this same capability. Sadly, I would estimate the "disadvantaged" to be 98% (or more!) of all the speakers out there. This sonic advantage exists not only with the new Frankenstein amplifier, it also applies with other low-powered SET amplifiers with an adequate (though not outstanding) damping factor, like, surprisingly, the highly modified version of my Golden Tube 300B amplifiers.

This may all be good news for Blume, and great news for those audiophiles who like (and can afford) the TVII, but my hope is that it is also eventually great news for everyone else in the long run. I must assume that there are other speakers also available with similar (amplifier friendly) characteristics; specifically high-sensitivity and, even more important, an ultra-easy impedance load, so that amplifiers with relatively low damping-factors are NOT compromised when driving them, particularly in the bass frequencies*.

(*Evidently, Israel Blume took some exception to what I wrote above concerning the "lack of weight" of the TVII/Frankenstein combination, or felt further elaboration was necessary, so he sent me a letter. Here it is:

"I realize the compromise with the Frankensteins in terms of extreme low bass reproduction or ultimate weight. It is not that I am unaware, it is that for me the ampsí excellences are so great, that the downside is very slight by comparison. After 6 months of living with the amps, I am fully cognizant of the fact that the bottom octave (20hz- 40hz) is attenuated. When playing (MFSL) Saturn through the Total Victory II with ASL Hurricanes for example, I have heard pictures on the wall start to shake with a visceral impact that was scary. This did not happen with the Frankensteins. This is the only area that I know the amps are compromised when compared to the best, big amps.

However, when it comes to midbass weight and authority, (an area of great importance to me) and bass articulation and correct timber, (again of vital significance since this range is almost always present in the music listened to), I actually believe the Frankensteins are almost state of the art. The amps get it right to a degree that surpasses virtually everything else I have experienced and this is more so since the latest mods.

Therefore, the objection I have with your comments is that you imply that I am unaware of the low bass flaw due to not having a speaker capable of its reproduction and because I have not heard enough different systems. I definitely know what is lacking. I have heard the Total Victory and Total Eclipse, not to mention the (Concentric Speaker Technology) Super Subs, shake my windows on Saturn and other electronic synthesizer works. I simply feel that the finest small SETs, will inherently posses this flaw due to the laws of physics. And this compromise in the overall scheme of things, is really a very small, easily lived with price to pay, at least for me.")

Personal Note-The point, that I was trying to make, was that Blume did not feel this problem was important enough to bring up at the time that it was evident and noticeable to both of us.

Top

READERS LETTERS

THE HISTORY OF THE ORIGINAL FRANKENSTEIN AMPLIFIERS

I have now received the updated history of the original Frankenstein amplifiers, prior to Israel Blume, from the actual person Blume purchased them from. Here's his letter:

"I just now ran across the section of your website that has the information on the Frankenstein amps that Israel Blume has. As it turns out, I am the person that sold the amps to Israel. I am certainly glad he has enjoyed them and is inspired to create a commercial product from the design. I liked the amps, but in my home office system, I had a couple of amps I liked better.

You should know that the Israel is the fourth owner of the amps. The original owner had Cyrus Brenneman do the initial modifications, but, in fact, did not do all the modifications that were recommended by Cy. The amps were later sold to a fellow in Chicago, who received them without any manual or documentation. I purchased them from him and was disappointed when I tried them out. In addition to sounding off, they developed a buzz in one of the transformers. I contacted Cy, who agreed to check them out for me. It turns out Cy lives only about 40 miles from me in Southern California. The buzz problem was one of the original Tektron transformers, that the original owner had elected to keep, rather than replace, as Cy had recommended. The overall sound quality problem was simply that the wrong driver tube was being used. Cy had designed the circuit to use a 6EM7 tube, but the second owner did not get this information and had been using a 6SL7. Needless to say, using the correct driver helped the sound.

The system I used them in is a home office system with monitor speakers, at the time Reference 3A MM DeCapo iís. Although these amps sounded good, I actually preferred a couple of custom amps I had that used 845 and 45ís as output tubes. By comparison, the Tektron/Brenneman amps were a little bit cooler sounding, were just a bit bass shy, and were a notch less solid in the imaging department. It sounds like the match with the bigger Coincident speakers was a better fit."

Personal Notes- This helpful reader has provided the definitive (early) history of these amplifiers. As for the described sonics, Blume has improved the amps quite a bit since the reader last heard them (see below). The bass is still a "bit shy", as I observed myself above, but the imaging is now rock solid, and the amps are now both highly detailed and as neutral (neither "warm" nor "cold") as can be imagined, at least with the Total Victory II, which is a highly revealing speaker.

Meanwhile, Israel Blume read the above letter with great interest, and decided to complete this interesting topic by listing all the changes that he made to the Frankenstein amplifiers.

Israel Blume's Letter

"Since you published the letter by the previous owner of the Frankenstein, perhaps it might be edifying to let your readers know what I did to the amps since I received them.

1. Power Supply Ė Increased by 50% and changed from electrolytic to all Solen polypropylene with V Cap .01 mfd bypasses

2. .22 mfd polypropylene coupling cap and paper in oil cathode bias caps changed to .47 mfd V-Cap Teflon

3. Input power supply caps changed from electrolytic to Solen polypropylene (47 mfd) and bypassed with .01 mfd V-cap Teflon.

4. Speaker binding posts changed to Coincident

5. On the input of one amp, variable resistor, on the other amp, metal film. Both removed and replaced with Vishay 100K

6. To ac ground on one amp, .01 mfd cap removed which caused amplifier oscillation after warm up. Other amp did not have cap.

7. New rugged IEC jacks replaced cheap standard type.

All the changes caused the amp to go from superb sounding to being a breakthrough."

Personal Note- I'm glad this all came out. It's always good to know what lengths you have to go through to truly optimize a component. (See "The Limits of Modifications" short essay, for a further perspective on this general subject.)

TEKTRON TK50M SET AMPLIFIER

Here's the latest information about these interesting amplifiers, and the history of the particular pair that ended up as the "Frankenstein". It is from Robin Wyatt, owner of Robyatt Audio Products. With some minor editing:

"I am very aware of those ("Frankenstein") amplifiers, as they actually changed hands many times. A gentleman in Chicago had them and tried to sell them back to me after the mods, probably the guy you mentioned. Then they went to an existing customer of mine in Baltimore. He had a Tektron integrated on Avantgard Duo's. Firstly, we found them overly noisy on the super efficient Duo's. I agree, in some areas, there were some improvements to the stock TK50M's. However I found that changing tubes, both brands, and types, made more of a sound change! The Tektrons are unique in the fact you can run three different tubes by switching filament voltage.

We did have serious problems at first with the US versions of the amps, because I specified a switch instead of internal hard wiring, as in the Italian versions. Those amps were early production. The original switches melted shut at 5.0V, allowing the use of only the 50 tube unless the switch was disabled, and hard wiring adopted! That is no longer a problem, as we use a $35 super switch from Japan!! Then we put a Sophia Electric "Princess" tube in the Tektrons, running at 3.5V, with no other modifications needed. This is the only amp I know that will run this tube apart from a now discontinued Sophia model. If you liked the "Frankenstein's", you would have been blown away with this combo!! I had to sell the tubes to the gentleman, he would not let them go. Note- These were the "Princess" tube Sophia sells, that is a cross between the 300B and 105D, and Not the new 300B "Princess". I believe the Brennemans were sold shortly after...

I will be demo'ing these amps at VTV Show, at the Embassy Suites, in Piscataway, New Jersey, May 6th and 7th.

Michael Lavorgna, of 6Moons, has one right now, and has heard how the "Princess" tube far out perform any new or NOS, 2A3, 45, 245, 345, 300B, 300BX, 50, 250, 350, 463, VT52, I put in the amps, be they EML solid plate 45's (his) or RCA Cunningham 1930's mesh plate 50's (mine)!!!

I will demo a stereo amp and pre, and will be using RL Acoustique Lamhorn 1.8's with AER MKII drivers, as well as the intergrated Tektron, with an Ipod type set-up, (must not forget the young crowd, our hobby is getting older!).

...Yes, the Sophia Princess is still available at Sophia Electric, and I believe existing 300B type amps can be modified!"

Personal Notes- I'm particularly intrigued by the Sophia Princess output tube. If Wyatt is correct, it could be a serious development, and the required modifications are probably not extensive, nor expensive. There's no question that the Tektron is an unique amplifier, especially suitable for those audiophiles who want to try a variety of low-power SET designs, while avoiding a huge initial investment in both time and money. They're also compact, attractive and have a proven history of successful modifications.

Some Further History of the Original Frankenstein

This letter from a reader fills in the origins of the amplifier that inspired the new Coincident Frankenstein. Only some minor editing, but my bold:

"Iím a regular visitor of your site, and I noticed with excitement that the Frankenstein finally unseated your modded Golden Tube. I visited the Coincident website and saw the photos. I have no doubt that the performance is phenomenal, but I would wish the amps looked a bit less edgy (with that hexagonal casing). But the sound is, of course, the first priority.

I also noticed with humor a while back your first mention of the Frankenstein. I was the very first person to have the Tektron monoís modded by Cyrus Brenneman. I was attending grad school in UCLA at the time, and Cyrus happened to be in the area (along with the famed Dr. Bruce Edgar, who is almost like a brother to Cyrus). One of the Tektron monoís had a failed power transformer and I needed someone to replace them, and found Cyrus. While he was making the repair, he looked at the circuit and suggested several mods, especially for the driver stage. The result was more of everything, especially detail & dynamics.

Thereafter, I sold the amps, with plans to get out of audio entirely due to personal circumstances, but my experiences with the modded Tektron amps (mated to RFT alnico fullrangers) remains one of my finest experiences, although I have more money now and am playing with more expensive stuff."

Personal Note- As I informed this reader in my reply to him, if it wasn't for his personal courage and passion in taking that initial risk to modify the Tektron, there would be no Frankenstein amplifier in the first place. Another example of how interdependent we audiophiles are. This reader deserves a serious amount of gratitude from the audiophile community, which will become more apparent as time passes.

COINCIDENT FRANKENSTEIN AMPLIFIERS AND MAGNEPLANAR SPEAKERS

I just received a letter from a reader with observations that truly surprised me. Here is the relevant part, with some editing and my bold:

"I thought I would try the (Frankensteins)... (After some disappointing results) I thought I would have a quick listen to them with my Magneplanar 1.6 speakers, out of curiosity.

I could not even imagine how a set of 9 watt amplifiers could sound good with 86db speakers. However, I was shocked* by the outcome. It is hard to describe the improvement. However, my music now sounds so natural and wonderful, that I am buying the amplifiers and will run them with the Maggies for the interim..." (4/09)

*So am I. I would have never advised using these amplifiers on any Magneplanar until this letter.

Personal Notes- I had no idea that the Frankenstein amplifier could be this versatile. My best guess is that the flat 4 ohm impedance of the Magneplanar is an easy load for the Frankenstein. At that point, it is just a matter of whether the top volume levels are adequate for the listener. For many audiophiles, this should not be a problem.

This happy result is also excellent news for the owners of other speakers with flat impedance loads (4 ohms or higher). How "excellent" can only be appreciated by those audiophiles who have actually heard the Frankenstein amplifiers at their considerable best.

EAT 300B Tube & Coincident Frankenstein Amplifier

A reader just sent me his positive experiences with the EAT 300B output tube. I don't have any experience with this particular EAT tube, though I do have their (now discontinued) 300BX, which I will try out when I have some free time.

"...having recently installed a pair of E.A.T.300B tubes at a horrific price, I felt compelled to write to you as the results are stunning. Huge dynamic range and clarity was my first impression. Now they are running in, very holographic and more front to back sounding, even from CD. Certainly worth the investment installing a pair of these..." (11/10)

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