Thought on OTL tube amps

simintju,you are right,most responses are coming from their noses,not technical.

Realdeal, unfortunately, Simon Vinitsky (Simontju) passed away earlier this year...

My experience with an OTL tube amp was not good. It is a very popular brand. I had 3 output tubes fail with loud pop within the first 6 months of ownership. It had excessive hum both mechanically and hiss through the speakers. While I have to admit it had the clearest and smooth high frequency of any amp I've ever owned, it's bass was loose even though I was told my speaker load was no problem for the amp by the designer himself. Soundstage was very wide but image lacked focus. In the end, I could wait or get rid of it. Of course, OTLs are system dependent, more so than others I think. I have Bob Carver Cherry 180, slightly modded, and it is by fall the most satisfying amp I've ever owned.

Ralph, can you either verify or put to rest the notion that the Futterman OTLs are inherently unstable? I have an H3 in decent shape I'd like to have brought back to life. From what I've found, there seems to be a serious contention that this has been rumored early on and stuck, however erroneously.

Futterman himself seemed to do a pretty good job at keeping the amps together according to one of our customers, although HP related an event in TAS that suggested that they could fail spectacularly.

I heard rumors about the NYAL stuff being not as stable but never knew anyone that actually had experienced a problem themselves. During the 1990s, that rumor was so prevalent that we came to call it the 'Futterman legacy' since it was our single biggest marketing problem. In essence, because we made an OTL people assumed it was unreliable. The simple fact that we don't have to ship amps back to be repaired if a tube fails is why we are still around after 39 years.

But I have no idea where the rumor got started. I do know that Fourier, who went out of business in the late 1990s, didn't help, but their amps had engineering flaws that had nothing to do with them being OTLs!!

Harvey Rosenburg (founder of the NYAL) was adamant that the amps had no reliability problems, even years after the company failed. But he had a lot of ego tied up in them and was never the most reliable witness so I regard his comments as a bit of a red herring.

So I really can't confirm or deny that rumor; sorry I can't shed more light on it.