What's your OTL tube amp experience and suggestion?

@atmasphere

Just to be clear, I'm not Trolling you, or your company, just answering the question in the thread title, "What's your OTL tube amp experience and suggestion".

By stating you made the first reliable OTLs does indicate that some or all of your predecessors were in fact, not reliable. And by safe, I didn't just mean not catching on fire, but rather safe and reliable in our systems.  The Berning ZOTL amps have no chance of passing DC, no popping noises, and extremely long tube life, again, on the order of many years to decades of daily use. If your amplifiers are capable of similar safety and reliability, I apologize for not knowing so.

And if some think ZOTLs aren't really OTL amplifiers because they don't meet some engineering criteria that fits their needs, well, I don't know what to say about that. I don't think anybody has ever sued Berning for false advertising.  Here's a nice discussion from the Berning website, including pros and cons of different OTL implementations, for those interested. http://davidberning.com/products/qz

It is accurate to point out that the Berning amplifiers utilize a "nontradional" output transformer that operates at very high radio frequency levels. This is a different type of transformer as compared to the common or traditional output transformer. This is different from the Atma-Sphere which does not utilize an output transformer at all. Both companies have earned reputations for excellent sound quality. Obviously each has their own unique character.
Charles 

@rusty_jefferson 

Just to be clear, I'm not Trolling you, or your company, just answering the question in the thread title, "What's your OTL tube amp experience and suggestion".

No worries- I didn't think you were. But most people don't realize the ZOTL amplifiers have not only an output transformer, but also semiconductors in the output section. It is quite unique!

By stating you made the first reliable OTLs does indicate that some or all of your predecessors were in fact, not reliable. And by safe, I didn't just mean not catching on fire, but rather safe and reliable in our systems. The Berning ZOTL amps have no chance of passing DC, no popping noises, and extremely long tube life, again, on the order of many years to decades of daily use. If your amplifiers are capable of similar safety and reliability, I apologize for not knowing so.

Sooner or later, if a tube fails the Bering will make a popping sound. But it unlikely to threaten a speaker.

You might think about this for a moment: If our amps were damaging speakers, we would not be able to stay in business for very long, instead of the 41 years we've been around. I'd be quite nervous if I thought for a second that one of our amps could threaten my speakers- the drivers in them are quite expensive. That sort of thing has a way of coming home to roost!

We protect the speaker with a simple mechanism which is highly effective. But that is not the only reason our amps are safe- we are the first OTL manufacturer to make an amplifier wherein the power tubes are in fact properly under control (which is really important; think about what that means for distortion too) and also, the first OTL that is unconditionally stable (which is to say: stable regardless of input condition or output load).

We too get long tube life (we warrant all the tubes in our products for a year) often on the order of many years to decades... so apology accepted- no hard feelings  :)

And if some think ZOTLs aren't really OTL amplifiers because they don't meet some engineering criteria that fits their needs, well, I don't know what to say about that. I don't think anybody has ever sued Berning for false advertising. Here's a nice discussion from the Berning website, including pros and cons of different OTL implementations, for those interested.

When the amp first appeared I read the patent, as it is patented. This is from the abstract of the patent:

"A linear audio amplifier includes a push-pull pair of vacuum tubes operating in a linear amplification mode coupled through a pair of dc-dc switching power converters to an external load impedance. Each power converter includes a **transformer** with one or more secondary windings that drive rectifier circuits, and the resultant dc voltage sources are loaded by their respective tubes."  (emphasis added)

Although connected in a quite unconventional manner (hence the patent), it is the transformers that effect the transformation from the high impedance of the power tube to the low impedance of the speaker, which otherwise is a rather conventional way of describing the operation of an output transformer.

In a letter to the editor of Positive Feedback back in 1997, David mentioned that he was originally going to call the amplifier a Zero Hysteresis amplifier but he found that to be difficult to explain. When he told people it was similar to an OTL then the glazed expression went away. It didn't help that Harvey Rosenberg suggested the ZOTL acronym, which Harvey told me specifically didn't mean anything as he knew full well the amp was not an OTL.

Had the Tenor 75 and Atma s30

The Tenor gave me no problems and had some work done on it  prior  to me buying them. Crazy great sound and  awesome looking but created too much heat in my Florida listening room. The equal to Atma

Atma s30 why did I sell it?? Stupid not to have gone to the m60 and just deal with the heat. Now in the market to buy a pair. Support is impeccable and reliability is off the charts great.  Bulletproof in my experience with the S 30.

Some years back I had the then most recent Atma-Sphere MP-1 preamp along with the MA-2 Mk 2.3 monoblocks.  They were driving Dynaudio Confidence C2s with the source being a VSE-modded Sony 777es.  The AS gear was the most transparent, fast, textured, layered equipment I have ever heard.  Everything just sounded right.

I also heard AS gear on the big (at that time) Sound Lab electrostats on a vinyl set-up. I can't remember what that vinyl rig was comprised of but what I do remember was it's total cost was in the neighborhood of about $50k.  THAT was the best system I have ever heard.

The only knock I had against Ralph's gear was the amount of heat they generated.  With the big monoblocks I had, I barely used them during the summer.  But the sound they produced was exquisite.  I also never had any problems with them.