OTL amps on Dynamic Speakers

Hi Justlisten, about OTL, there are several different OTL output stage designs: single-ended push-pull (SEPP) or circlotron. Fourier was using SEPP design. Atma-sphere, Joule Electra, Graaf are all using circloron output stage.
Fourier is out of business, and a much better one with SEPP output stage design is Transcendent Sound. I am not very familiar with Duntech, but you could call Bruce at Transcendent Sound to discuss about using OTL's with dynamic speakers. Best wishes.

Highly recommend is the David Berning ZH-270 OTL. It has no problems with lower impedences because of its ability to match speaker impedence and increase power output into these more difficult loads. This design is most likely the most stable OTL design and does not use "brute force" technology by any means, uses a patended resulting in a more stable amplifier. Its power consumption at idle is a mere 100W and a maximum of 300W at full power output, you can adjust feedback on the fly, is stable into 2 ohms (and probably lower), tube life is an estimated 20 years, and can be mated with any speaker that a solid state amplifer within the similar equivilant output power can be mated to. Only most of the solid states don't sound as good as an OTL :)

Chris

A product called the Zero Autoformer can be really helpful item mating your OTL to your speaker. I have replaced my speaker cable with this product with truly great results. Check out this link at the Atma-Sphere Owner Group site http://www.condor-connection.org/asog/tweaks/ps/zero/index.html

No one mentioned the Berning ZH270, a reliable otl tube amp.

Thanks for the advice guys, the last time I owned Otls, Counterpoint Sa4s, I had Mlogans Sequel 2s and Stax F81s and never had a chance to see what they did on a coned speaker. I now have Duntech Black Knights and may see what an OTL can do on those

Another one to consider especially if you're on a budget is the Transcendent OTL. Dead silent, quick as any solid state I've ever heard and as Jtinn notes, quicker than transformer coupled tube amps. This amp also has excellent bass definition along with all the other attritubes of OTL designs which is that harmonic purity and clarity and second to none high frequency extension with air on top. You have to hear these amps produce a well recorded operatic soprano, say Renee Fleming or Kathleen Battle to really appreciate this. It is a beautiful thing. Another nice thing about this amp is it doesn't run as hot (300 watts at idle) as the single ended OTL's which can really heat up a room.

I am using this amp with the Merlin VSM-M which is an 8 ohm load and 89 db efficient. The Transcendent mono's will drive a 4 ohm load according to Bruce, the designer.

I am driving Audio Physic Avanti III's (89db, benign 4ohm load) with the Tenor 75w OTL's and it is the best sound I have ever had. My room is 15x25x11h. Hope this gives you some reference.

While I was not aware of the Jadis being an OTL, the Fournier is a wonderful sounding amp. Others that would do the job quite well are the Atma-sphere MA2's and the higher powered Joule Electra's.

I drove the Wilson MAXX's (92db) quite well with both the Atma-sphere's as well as the lower powered Tenor's. The MAXX's are deceptively tough to drive, complex crossover as well as a 13" and 10" woofer.

The OTL's were much more extended and natural in the highs and also sounded much quicker than the transformer based amplifiers I have had.

Go for it!

i might recommend the Atmasphere line as one of the the best and most stable OTLs with dynamic speakers. the M-60, MA-1, and MA-2 are all solid and excellent performing.

i used the MA-2 MKII.2 to good result on the very difficult to drive Wilson Watt/Puppy 6s. many less powerfull atmasphere amps are used with numerous dynamic speakers.

personally i own and also recommend Tenor Audio 75Wi monoblocks, an integrated OTL amplifier that i prefer if your speakers are a stable load and 90db or better efficient.

www.atmasphere.com / www.tenoraudio.com