Thought on OTL tube amps

FWIW,I've owned an Atmasphere S30 for 10 years almost since it's introduction currently updated to the latest 3.1 configuration.
Over that time there have been no significant mechanical/reliability issues. IMHO, these "OTL concerns" date back to the Futterman amps and their clones. Unfortunatly, modern day OTL manufactures are unfairly lumped in with them.
AFC, I have not heard the ZU Essense but on paper it's a match made in heaven with the S30. With the Zu's minimal crossover there would be very little between the output tubes and the Z4 driver except the speaker wire.
Have fun.

There are some very nice options to choose from on the OTL amp market these days. Atma-Sphere, Berning, Joule Electra, and Transcendent Sound to name a few. All of which are very reliable. It's rumored Roger Modjeski at Music Reference is working on a new OTL design. In addition, there are some great speakers that are OTL friendly, including Merlin (Bobby P. uses a Joule Electra set-up at the audio shows), Zu, Audiokinesis (Duke uses Atma-Sphere at the audio shows), Classic Audio, and Tonian Labs.

I myself own an Atma-Sphere S-30 that I use with my Audio Kinesis Jazz Module speakers. The S-30 was actually used to voice the speakers. I also own a Berning Micro ZOTL which although 1 watt, can drive my Tonian Lab TL-D1 speakers nicely in my small room.

Thanks all. What are the purported advantages of OTL amps over those with transformers, aside from eliminating possible transformer hum and obviously making the circuit more "pure" in a sense? Hum isn't an issue with the MastersounD or the Frankensteins I have. I'm just looking for ways to get different sound, see what I prefer with different types of music.

Anyone have any experience with McAlister amps? Plenty powerful, and a unique build, using old television horizontal sweep tubes rather than standard power tubes. Claims to greatly extend tube life, since the old TV tubes tolerate much higher plate voltages than do standard audio power tubes. They also have one that's tremendously powerful- 195 watts per channel. Pretty salty for a tube amp. They also have a very, very attractive price point.

With my speakers, Merlin VSMs, the Atma-sphere M60s have proven to be the best all around amps for my taste, up against a few amps I have had in rotation in my system, the best of them being the CAT JL2, Pass XA30.5, First Watt Aleph J, Music Reference RM Special Edition, and Quicksilver V4s - that is, for me the OTLs produce the best sound up against some of the very best tube and SS amps made - though the Music Reference is right up there, and have no doubt that with more difficult speakers might edge out the OTLs, but with proper matching (not hard to do) OTLs are pretty tought to beat. I would put the Joule OTLs right up there with the Atma-sphere, you cannot go wrong with either IMHO.

A good OTL has the immediacy and presence of a SET amp while generally providing even better bass response. You will also hear a lot of people using the word transparency. OTL's have a liquid yet very neutral and open sound. I love both OTL and SET amps. I own an Atma-Sphere S30 as well as 45, 2A3, 300B and GM-70 SET amps. I would not part with any of them. To my ears the SET amps colour the sound more than an OTL does but the sound is so gorgeous I don't care to be a purest. I find I use the S30 OTL and GM-70 the most. They have more power than the smaller SET's and I find they are also better balanced - not unduly emphasizing the midrange like the 300B does (which can be wonderful in its own right depending on my mood). I think all audiophiles should experience both a SET and OTL amp as a right of passege during their audio journey.