Why no threads on OTL amps?

Definitely include the Berning 270 for OTL's which put out little heat, the 270 puts off very little heat, in fact less than any other OTL I can think of. It also does not use much power from the AC - 100W@idle & 300W max. and increases output power into lower impedences which no other OTL does. This is really breakthrough technology for OTL tube amplifiers.

Regards,
Chris

I took my ZH270 to my local high end dealers' for him to listen to. It was sitting on a rack, and a customer came in and saw it and asked the dealer how he could cook anything in such a small microwave! Later, a little kid came in with his parents, saw the 270, and said "Wow! An EZ-bake oven!" True stories, but may also illustrate why the 270 sometimes doesn't seem to "get any respect"--it just doesn't look as impressive as some of the others, with rows and rows of output tubes in each mono-block.

Regarding Berning, my dream amp is the Seigfried: a 300b ZH type OTL w/12wpc and dual volume pots to allow direct input. It's killer. And like the ZH270, it will drive low impedances with authority. Talk about perfection, a 300b, pure class A single ended triode, ZH type OTL,with low heat/low power consumption, 20 year tube life, direct input capable, and drives difficult loads and is extremely reliable. And I believe, auto bias adjusting. I think it's around $7500. I'll bet it will squash the Tenor amps flatter than a pancake. Looks really cool, too. BTW, I have the Berning MicroZ OTL(1wpc,pure class A triode) and it is a jewel. I have NOS tubes(Mullard 6201,Sylvania 6sn7wgt) in it and there is no way I could describe the performance level(that you would believe, anyway). You have to audition one of these, with good single driver high-eff. speakers. It will knock your socks off, and you will never think the same way again about low power amps. All the accolades spoken above about the ZH270 also apply to the MicroZOTL. If you choose your speakers to match it, you will never need more amplifier.(Maybe a separate sub/amp if you like that set up). Also, it makes a great bi-amp system with one on each side for inexpensive OTL bi-amping if you like 2 way speakers, or even a crystal clear tweeter amp for multi-amp systems. It even has a headphone output jack. No one that has listened to mine believed it is only a $750 amp. Very highly recommended.(It will also run on a 12vdc battery which completely eliminates power grunge problems and the entire 120vac power supply section, or you can just plug it into the wall if you want, no wall-wart, uses IEC connector so you can use the super duper power cords, too.

Twl-When you think of SETs you think of the late Gizmo Harvey Rosenberg of NYAL's fame. He went absolutely bonkers over the Seigfried and the zero hysterisis technology in general. The ultimate realization of tube technology today must include the Siegfried with either the 300b or 811 triode. Imagine a low powered SET that isn't limited to that magical midrange but expands its performance into the high and low frequencies as well. Regulated switching power supply and an OTL output stage, dead quiet, auto biasing, reliable, low heat and elimination of transformer related distortions. Where do you go from there? I guess it can be refined but in reality Berning has established a new path and there seems to be a hush over it in the audio community. I haven't heard this amp yet but can only guess that it sets new benchmarks for SET design and may be near the pinnacle of reproduced audio with the right speakers for those looking at this approach. There is much to be said for low power and highly efficient speakers. The zh270 itself is so incredible that you really have to wonder about the advanced level of design and engineering in these special products. I haven't stopped wondering since I got mine over 2 months ago.

Kris: Your statement of "The Berning in my opinion bested the Tenors in every way. Speed, clarity, bass, and of course that magical otl midrange", is quite a reach considering you were listening to two entirely different systems. That is like listening to a system in Montreal and saying did you hear how good those power cords were? It just is not a real valid statement.

Since I have not heard the Berning amps in my reference system, I will not make any statements as to whether they are good or bad. It would be impossible for me to do so with a clear conscience.

The Tenor amplifiers are the finest amplifiers I have ever heard. Nothing I have heard is even close and that is why I took on the line. The Tenor's can handle impedance swings as well as any OTL. What they do not tolerate is what any 75 watt amplifier would have a problem with, inefficient speakers. I have had them on 86 db Eggleston's and they do great within a reasonable limit. If you are looking to drive an 80-86db speaker at over 100db, these amplifiers are not for you. I know at least two people driving Watt Puppy 6's with a pair of Tenor 75's and they could not be happier. The 6's are a 4 ohm speaker that drops to about 2.

Twl: Your statement of "I'll bet it will squash the Tenor amps flatter than a pancake" is quite funny and I will be happy to take that bet anytime you want. How much money you have? :)