OTL amplifiers

Dfrigovt, it would be a shame if you concluded that these OTL amps are troublesome or finicky or are only good for "optimal" setups with "perfectly matched" speakers. Proper amplifier/speaker synergy is something you need to concern yourself with regardless of what type of amplifier you choose. When I read comments from people warning of the need to "change tubes as often as they change the oil in their car" or other critical remarks, I have to wonder if this is coming from someone with personal experience with OTLs. As a Joule VZN80 owner I can tell you that my personal EXPERIENCE with this amp over the last few years shares nothing with the comments from Marakanetz. It has been nothing but a pleasure and, next to my speakers, is the smartest purchase I have made in audio. With respect to my amp, the idea that you need to frequently change tubes is absolute baloney. Quite frankly, it's a bit annoying to read comments that broadly label OTLs as having that problem. After three years I am still using the original tubes in my amp with absolutely no problems.

As for speaker matching, one thing to keep in mind (with respect to the Joule at least) is there is no problem using the Joule OTL with 4ohm speakers. In fact, Joule provides power ratings for both 4 and 8 ohm speakers. In fact, Jud Barber of Joule designed the amp to be capable of running his own speakers - Duntech Princess. Those speakers go below 4ohms. One nice thing about the Joule is that the feedback is variable - each channel, progressively. So, that means you can dial in the amount of feedback to suit your tastes - and the damping that your speakers seem to match well with.

As far as being "finicky" I will tell you this. I have had absolutely no problems with my Joule. Zero. From a practical use standpoint this is the way it works. You tell me if this is too finicky for what could be the best, and last amplifier you will ever need to buy... I take 30 seconds to turn a dial up (Variac) to operating voltage which you can read on a built in multimeter. It starts making music right away. 10 minutes later I get off my butt to tweak the voltage (once the tubes heat up). That takes about 10 seconds. That's it. Every half hour or so I may peak at the voltage while I change records. Sometimes I do. Sometimes I don't. No big deal.

In my opinion, saying an OTL amp is finicky is like complaining about engine noise from a V12 Ferrari.

I won't even get into the fact that the amp is built like a brick house, etc. I fully expect it to outlive me (I'm 31). Eventually I will have to replace tubes I guess. I don't view replacing tubes every 4 or 5 years as being a problem.

BTW, I have Merlin VSMs. You owe it to yourself to hear an OTL. I suspect many have no idea what they are missing.

Best wishes.

Jim

Dfrigovt, consider this fact, Atma-sphere has been manufacturing OTL amps since 1980, Joule since the early 90's, Transcendent since the mid 90's. The others I really don't know, but the Tenor is certainly more recent and the Berning which uses a completely different approach, was brought out I believe in 1996.

There were major considerations of owning such an amp in the past. The Counterpoint SA-4 and NYAL amps are really the only ones that contributed to the bad reputation of this design often because folks used them with the improper load. Harvey Rosenberg was very defensive of his design and was adamant that most of the problems were caused by audiophiles not paying close enough attention to this.

I am not trying to sell you on anything. If you like tubes I would say that a OTL is no more maintenance than a regular tube amp. The tubes should last a long time on the above mentioned amps. The outputs on the Joule the 6C33C are projected to last over 5 years. I believe the Tenor uses the same output triode. Audio Research 6550's are recommended for replacement every 2,000 hours, cost per tube is similar, about 30-40.00 each to replace. The Atma-sphere tubes are even less. The Transcendent's are about 20-30.00 each. Atma-sphere even less. I have not heard of ONE incident of catastrophic failure of either speaker or amp with the above designs. The advocates of these designs are speaking from experience. My guess is that Marakanetz is not but purely from an engineer's perspective based on what COULD happen with such a design from a purely theoretical viewpoint and how a transformer would act as a buffer in the event of failure. His concern seems to be about DC at the input of the speaker without a capacitor to act as a buffer. I can't speak for all the designs but I know the Transcendent uses fuse protection but is direct coupled. I'm sure the others have addressed this. Maybe someone else can offer input to Marakanetz's concern regarding this with the other amps. If not call the manufacturer and ask. Knowledge is king, misinformation is of no benefit to you or anyone else reading this thread. Get the facts.

Jud Barber has been working with tubes since the 50's, and also is an engineer. Bruce of Transcendent is an electrical engineer. Ralph I don't know. I think their experience and success with the reliability of their products would qualify them to a greater extent than someone providing theories as to what COULD go wrong and making absolutely erroneous remarks about replacing tubes regularly. The same for Atma-sphere. This design is mature and refined. See if you can find any horror stories about Atma-sphere amps blowing up.

The point is this as it is with anything audio, it is up to YOU to find out to your satisfaction the reliability of these amps. The users of current OTL amps disagree adamently with the naysayers who probably don't own or have NEVER owned an OTL amp. First thing you need to do is listen. The newer designs DO work to 4 ohm loads but as stated above, the OPTIMAL load is 8 ohms or higher. There are many speakers that qualify. Talk to the manufacturers'. Jud of Joule, Ralph of Atma-sphere and Bruce of Transcendent will give you the low down of the do's and don't for their respective designs. Each of these designs are considerate of the past failures that has led to the current reputation (by some) that OTL's are somehow still unreliable.

Like Jim, I've had my Joule-Electra VZN-80 for three years and have not had a single problem.

I would like to say that I am sure the recount of Ralph Karsten demoing his amps' ruggedness by shorting the outputs with a coin and having NOTHING happen is 100% accurate.

The reason I say this, and I am not proud in doing so, is one a couple of occasions, I have shorted the amp by moving my loudspeakers around, frantically trying to wrest that one extra bit of performance via speaker positioning. The stiff loudspeaker cables were not as compliant, and the amp was shorted.

What happened? Nothing!

Except for maybe in one bad situation, no sound coming out of the speakers for a second or so, until I realized what I just did. As soon as I unshorted the amp, the music immediately began playing again. Same as it ever did.

I didn't even blow a fuse!

The only times I have blown fuses was when I really wasn't yet adept at biasing the amps, and I had one setting way out of wack. Other than the fuse, nothing else was wrong.

How many amps, tube or solid state, can match this kind of performance???

I have owned 2 OTL amps, and still own one of them. The ones I have had have been just as reliable and easy to use as any solid state amplifier I ever had. Absolutely no fuss whatsoever. But the sound is better than any other amp I've had by far. I see no reason to avoid OTL for reliability reasons anymore. That is simply a part of their early history, and has no impact on the current crop of OTL amps. I have the Berning ZOTL-type, and I think it may be the best design of all amps ever. And if you want a SET OTL, then it is the ONLY choice possible, because nobody else can make a SET OTL, except Berning.