Why no threads on OTL amps?

"The Tenors can handle impedence swings as well as any OTL."

Not true actually, the Berning OTL's INCREASE output power into lower impedences. The Tenors cannot do this simply due to the nature of their design. This does not mean they are not great sounding amplifers, it just means they will have to struggle more with more difficult loads than a single ZH270. Lets quickly look at a couple specifications -


Tenor 75wi (monos) - @ 4, 6, 8 ohm - 55, 75, 75W respectively.

Power consumption - 730W (not indicated if this is idle or max.)

Berning 270 (stereo per channel) @ 8 ohm - 70W (84W output at onset of clipping), 4 ohm - 110W at onset of clippin.

Power consumption - 100W @ idle, 300W max.


I doubt the Tenors (or any other OTL) withstand less than 2 ohms or less for very long without losing steam, they were not designed to drive those difficult impedences with any consistancy. A ZH270 I know for a fact will tolerate quite low impedences for extended periods AND can provide much higher ouput power into lower impedences because of its unique ability to match impedence.

For example -

I personally heard the ZH270 drive a pair of Magnepan 3.6QR's LOUD with lots of drive tolerating some huge dynamic swings while playing some crazy techno music. For the kind of headroom we had one would think we were using some big solid state bruiser, but we weren't. We were using a single ZH270 with the difficult to drive Maggies.

Any 70W amp has its limits, true but we are discussing the subject of OTL amps specifically and I would welcome a friendly comparison with the Berning ZH270 and a Tenor Classic 75wi. I am confident a single 270 would do more than hold its own with the Tenors, especially with difficult to drive speakers like the Magnepans and/or ESL's for that matter.

Chris

http://www.condor-connection.org/slog/bbs/messages/422.html

This is an link to an image of a cutting edge, state of the art designed OTL amplifer made by David Berning based on ZH technology used on his current product line up.

As you can see by the internal layout, this is a radical departure from the conventional OTL technology based on Futterman principals some 50 years ago.

This mono block weighs 8 or 9 pounds and puts out 120W into 8 ohms and INCREASES output power into lower impedences.

Just for a minute, think of all the limitations and drawbacks associated with the current OTL amplifiers. Now think about one without these limitations, not possible? Incorrect, it is possible and happening right now.

Jtinn, my recommendation to you as a dealer would be to audition the Berning line in your system. I believe that if you do this, you will pick up that line as your new reference standard. I am sure the Tenors are exquisite amplifiers that anyone would be proud to own,with great sound and beautiful build quality. I do not intend to knock them and perhaps went overboard with my "flat as a pancake" statement. However, as Tubegroover stated, Berning has established a new path for OTL that creates a new standard in the OTL field. The typical circlotron OTL circuit topology has been superceded. The inherent circlotron weaknesses have been replaced with a superior design. And, of course, the previous cathode follower and Futterman designs had been surpassed years before by Ralph Karsten and his Atma-sphere circlotron design. I love OTLs and all of the great amps out there that use OTL design. I just have to recognize that there is now a superior design that will take us further toward OTL perfection, and that design is the Berning Zero-Hysteresis OTL amplifier. Cheers.

Thorty 40, I couldn't pull up your URL with my search engine. Would love to see that design. If you could find another way for us to see it, it would be much appreciated.

Twl, well put, your comments hit the nail right on the head. Why do so many seem resistant to the thought of a more evolved OTL design? That is my question.

Try this -

www.condor-connection.org/slog/

Then goto SLOG on line, view archives, on line archive 1, scroll to roughly the middle of the posts and find "here's the correct image" by Brian Walsh 10/24/01 and click on the thread.

That will take you to the picture.

Chris