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In Reply to: Re: I do use OTL's and personally love them... posted by Rich Brkich on October 19, 2004 at 14:05:14:
Rich, I mean this only in the gentlest way, but since your own last name appears to be shy a few vowels that is perhaps why you did such a bad job of spelling the names of the most well known OTL designers. You got Julius' name correct, but after that it's "Rosenberg", "Karsten", "Judd (Barber)", and "Rozenblitt", respectively.I can provide some history dating from Futterman forward. I had the privilege of knowing him, and in the 70's he built two sets of monoblock amplifiers for me. Whatever one may say about the sound of those amps, they were dead nuts reliable in my hands. I kept the second pair of amps for about 20 years and changed the output tubes once after 10 years, only on the empirical judgment that 10-year-old tubes probably needed to be replaced. Bias-ing them was a 10-minute job using Julius' instructions and a voltmeter. Also, let me say that he was one of a breed of craftsman that is in all too short supply these days. He was honest and caring, and he really sold his time and products too cheaply. In the late 70s, Harvey acquired the rights to build amps with the Futterman type OTL circuit at NYAL. I never heard or owned a pair of NYAL amps, so I cannot comment on their sound or reliability. George Kaye, an engineer who worked for NYAL, made some mods to the Futterman circuit to improve the bass performance. In the 80's there were several other iterations of the Futterman-type circuit (single-ended, "totem pole" output circuit). These included the Counterpoint SA4, the KSS amps, the Fourier amps, Prodigy monoblocks, and eventually Transcendent. The Counterpoint and KSS products were apparently very unreliable, and it may have had something to do with the fact that both designs did away with the output coupling caps that were in the Futterman circuit to protect the speakers from DC. Fourier amps were also unreliable but perhaps for different reasons, maybe due to quality of construction issues which also apparently plagued the KSS. I owned a pair of Prodigy amps in the early 90s, and they were also totally reliable and were built like tanks, sounded better than my earlier Futtermans. Rozenblitt made some changes in the basic Futterman topology that apparently also improve bass performance and overall sound quality for Transcendent compared to all the earlier products. And of course the Atma-sphere amps are a totally different animal, using a balanced input circuit and a balanced output based on the circlotron, no relation whatever to Futterman's original design. My Atmas are indestructible and it is almost impossible to imagine how they could ever damage a speaker without gross abuse. In summary, the whole notion that OTLs are inherently unreliable is baloney and always was baloney, probably perpetuated by makers of other types of amps that cannot compete with OTLs in sound quality.
Follow Ups:
The Futterman amps had no circuit board. Because of high negative feedback the input tube which provided all the voltage gain in the amp (6EJ7) had to be physically very close to the RCA type input socket. I found the best 6EJ7 tube for my H3AA's to be Siemens Halske made in Western Germany. These have mesh plates. Far superior to anything else I tried, and I tried every 6EJ7 type I could find.New York Audio Labs used circuit boards. Futterman did not. I think this was a critical factor in how each approach to essentially the same circuit sounded different. It was conveyed to me that this fact was particularly annoying to NYAL; that what Julius' built on a Budd box in his appartment just sounded better. He did not use fancy parts. I got the feeling he shopped for the best deal on what he needed at the time.
The H3AA had no power switch, just an attached power cord. I remember it was always interesting to plug them in. On cold start the current inrush was so huge it would dim the lights and the amplifier would almost physically jump. The transformer would emit a short groaning sound and settle down to a low almost inaudible hum. Never blew a fuse though. The amps worked every time. No failures, no smoke, and no fires. It was really something to see the forest of tubes perched on top all lit up.
Each 6LF6, the last of the line of increasingly more powerful horizontal output tubes made for color television, was individually fused with a small piece of #44 copper wire. If the tube shorted the wire would vaporize. Neat and inexpensive protection. I think it was the reality of ever more expensive and poorer quality 6LF6 which caused me to accept an offer to purchase.
The great magic with the H3AA happened with electrostatic speakers, though I got great results with dynamic types. It was the midrange that would make you sit down and listen. Grain free, musical, entrancing. It was truly magical.
The OTL works best into higher impedances, as we all know. I think if speakers were offered with 16 or 32 Ohm voice coils it would spark a renewed interest in OTL.
PS - a quick note re Ralph K and Atma-Sphere. It always sticks in my craw that talent/brains/creativity can be overcome by jealousy, greed, lust for power/control, or whatever. I have seen it many times in many companies ( and countries ). I hope Ralph can take some comfort in the fact that many many loyal customers and fans of his opus are standing behind him no matter what.
It should give those who have fomented this coup pause. Perhaps it would be unwise to treat Ralph unfairly. It could hurt the company, the product, and themselves. Better think about it, boys, unless you are just thinking of yourselves.
I think Julius told me to use those mesh-type 6EJ7s, too. I remember being in Julius' "factory", a room or two in a walk-up on 72nd St near Broadway in NYC. He usually had a transformer cooking in the same room, probably spewing out PCBs all over the place. He had huge boxes of new 6LF6s just lying around. He loved his headphone amplifier perhaps the most, and on at least two occasions he asked me to listen to the latest version on his headphones. He had a helper, a man who appeared to be much older than Julius (who was then in his 70s), who never spoke in my presence. He charged $5 each for tested replacement 6LF6s. I also remember the "hardware store" parts quality and the lights dimming at turn-on. After he passed on, I needed a single 6LF6, because one cracked due to my own mishandling of the amplifier, and I contacted NYAL. Harvey said he and he alone had the "data" for my particular set of amps and that he could sell me the tube I needed for $50. Instead, I bought a bunch from a local distributor for much much less, and the randomly selected new tube biased up just fine and lasted to the end of my ownership of those H3aas. Although they are culturally about as different as two Americans can be, there are a lot of similarities in character between Julius and Ralph Karsten, and I mean that as a compliment to both.
Lew - I did not know this - that you knew Julious??? COOL!My NYAL OTL3s *were really good* 15 years ago . . . compared to most amps around . . . (sadly didn't have Ralphs gear, could NOT 'afford' much more then) . . . BUT, they always had a character, probably the PC boards.
One of the HUGE appealling factors for me, for RALPHs gear was the fact of p to p wiring.
I would love to experience H3aa?? some time.
Harvey WAS NOT NICE to me either related to support of my OTL3s
on the several occasions that we spoke . . .
Did not mean to impugn the reputation of Dr. Gizmo. I approached him as a total stranger and non-customer, so I don't blame him for trying to make a profit on selling me a 6LF6. I was trying to point out the basic reliability of those amps built by Julius himself and Julius' humility. He had a cult following in NYC in those days, and there was a long waiting list for his amplifiers, but he continued to make them one at a time, including, as I mentioned, his own power transformers. Apparently there was something unique about those transformers.
I am sorry Lew, I did not mean to infer or distort anything from your message, in fact I sort of took a tangent. I guess that I have been somewhat uneasy with certain manufacturers (personalities) and may have improperly assumed this of other companies when considering their gear. Some are and have been more standoffish.Ralph IS and HAS been the very best to work with (feel extremely fortunate to have realized this) hugh measure of hands on approach to business.
I don't know if Judd is a formal first name or not, but he goes by Jud with one d as it is short for his full first name Judson. Frankly I am amazed I spelled Futterman's name right and managed to get Harvy's wrong. I never had the honor of meeting Mr. Futterman, but I had the honor of knowing Harvy in recent year before he passed. My apologies to Bruce for mangling his last name!Great historical info Lew! Very interesting reading.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison
I agree with Lew.
I've owned quite a few OTLs and have never experienced reliability problems with a single one.
I concure even with (possibly lessor???) NYAL OTL product. Sorry George.No problems . . .
However, I could imagine some chucklehead pairing *inappropriate speakers
or not maintaining (pampering) them and in turn causing 'so-called meltdown'.More likely, I feel - OPERATOR ERROR - I'm sorry.
I mostly used ESL63, 57s and LS 3\5a with fabulous results.
Also, it's worth noting that *most* OTL designs require more devices (tubes) per watt, compared to a conventional design. If an OTL with 8 power devices services as well as a conventional design with 2, that says a lot for the quality of the OTL design (as well as the devices used).
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