OTL amplifiers

Dfrigovt

I would like to mention for your information a few other details. I like you have eclectic tastes in music. Without doubt the most difficult music to reproduce accurately as you might hear it live is orchestral and choral music. The natural layering and individual voices you hear in a great live performance is something that I treasure when I experience it. To build a system that can capture that magic in a home environment is a worthwhile goal. It requires committment, but you can really get close. I wouldn't say that OTL's are for everyone as there are many downside considerations as noted above. All I will add at this point is that you try to listen.

So far as expense goes, Clueless is right about the Transcendent, it costs 2.1K for the T8-LN. It produces 25 watts and is great for a very efficient speaker with a stable impedance of say 6-8 ohms in a small room. I've owned this amp and would recommend it in a heartbeat to anyone that meets those specific requirements. I also believe this amp is an excellent value because it does all the things that seems intrinsic to OTL's if to a lesser degree at a very reasonable price. It is a very serious amplifier.

So far as the Joule goes, I had the opportunity to listen extensively to the VZN 80 stereo amp in my system . At the list price of 8K it appears on the surface to be expensive but when one understands that it is handmade (hardwired, no circuit boards) by the owner Jud Barber, has features including a variac to slowly bring up the voltage of the tubes to the correct operating level, individual biasing of tubes for optimal performance, no guesswork, variable feedback setting along with impeccable fit and finish I think its a bargain. I wouldn't have said this before I experienced this amp . Excuse my excitement but I'm not finished yet!

The amp I currently own is the Berning Zh270 ZOTL. I'm not going to even attempt to get technical because I don't completely understand how it works (Clueless's comment about Berning being bright may be a little understated :) It runs cool 100 watts at idle, can be used without a pre-amp, has 3 feedback settings which effectively can match it with lower impedance speakers, those requiring more current, without changing character or showing if you will a "personality" especially one that may be offensive. It is very tweakable and in my 1.5 years of ownership my excitement hasn't subsided, it just gets better. This amp costs 4.5K retail and I would just love to hear the amp at this price point that competes in the area that this amp excells, top to bottom clarity, no grain, glare, grit, grain or any other gosh darn G word you can think of. It is just amazing. And it also does bass very, very well.

The above 3 I have listened to extensively in my system. The rest I have heard on several occasions in different systems so I can't comment beyond the fact that every system except one (I think it was the speaker's I didn't like) had some serious magic going on. They are definitely worth looking into if you are willing to live with the speakers that would qualify their use in your system. Music is all about connecting to the emotion, these amps are better at it because they just get closer to it. In my experience I would say that their price to performance is excellent contrary to Mark. Cavaet, YMMV and IMO a comparably good transformer coupled tube amp will cost more.

Gs & Cluless

The disadvantage (inconvience) I speak of is not of any but consideration of ownership of such an amp that would be a space heater in their room. So far as OTL topology goes Gs, even Class AB OTL's (Transcendent) do run hot because they have so many output tubes although the heat output is less than a Class A topology (Joule, Atma-sphere, Tenor) Many would not consider an OTL simply because of this factor, too bad. Living in Florida or a warm climate is a consideration but it becomes less so after listening.

Marakanetz, what is your problem? Did you EVER had chance to listen either SET or OTL designs? I noticed you were equaly 'angry' over SET amplifiers some time ago.

I'm OK with SET
I'm not OK with pricing of SETs that basically require a knowlege of elementary school graduate to build them. Should be at least 10x- cheaper. I'm not OK with pricing 300B triodes as well.
As to OTL's distortion-free listening I'm OK as well BTW SET and OTL are completely different since OTL-s use mostly push-pull circuits except probably for headphone amps.
It's not OK with me the rest of inconviniences and again pricing. I agree that Bearnings are priced OK and could be the exception from the rest of OTLs.

Now I do realy have a question about DC at the outpu on OTL-s... Is there an output capacitor I assume?

Oh boy, where to begin? Firstly, I should say that I have been an Atmasphere S30 owner for the past 4 years. It is simply the best amp I have owned. They have a speed and transparency that, IMHO, no transformer-based amp can match.

The original futterman design and the NYAL clones of Harvey Rosenberg where notoriously unreliable and unfortunatly this reputation plagues current OTL manufacturers to this day. I only have experience with atmasphere(AS) which has run flawlessly. AS/tenor/joule amps are NOT futterman designs/clones and it's unfair to lump them together under the banner of "OTL".

Regarding the heat issue, any class A amp, like AS, will run hot. This includes tube or solid state. Yes, the big AS amps (225 and 140 watts/ch mono) can mimic "space heaters" but in actuality, it is my understanding, that they run only 10% hotter than their class A solid state equivilents.

The big AS amps will drive 4 ohm loads easily. With the S30 and M60, speakers have to be chosen more carefully.

Finally, about price. My S30, as optioned, went for $3150. It smoked a pair of well known SET mono's that went for $6000. I don't want to call AS amps "bargins" because they are expensive, but for what you get I do think they are one of audio's best values.