Transcedent Sound OTL amps

[Cogito]

Anyone know where can I audition any Transcedent Sound OTL amp in MD/DC/VA? Looking to build an OTL amp in the winter. Transcedent Sound T8 or the Beast sound interesting.

[Jim G]

I just noticed this thread. You know David Berning is in this group, right? I'm sure he'd be happy to talk OTL amps with you.

[tomp]

You should talk to David because his OTL solution is very different from all the others and IMHO vastly superior.

Tom

[Pelliott321]

Just curious Tom, have you heard every other OTL amp out there. Or is your opinion just a guess.
TS products have a very big following, been around for quite awhile, very reasonably priced. The case work is not much to keep price down, just Low price aluminum junk.
I have two of his products and I would put my phono preamp against any out there.

[tomp]

I have heard the original Futterman and atma-sphere amps. They are better than most transformer coupled amps but their output impedance is high which makes them very susceptible to speaker impedance. The advantage of the ZOTL that David uses is that there are also no iron problems that plague transformer coupled amps but the output impedance is very low compared to OTL amps, sometimes by more than an order of magnitude. There is then much less of a problem with matching to different speakers. The smoothness, clarity and transient response of his amps is superior. I have yet to hear any other tube amp that I like better than those from David but hey, that's my opinion. He has also gotten rave reviews in some of the major magazines for those same qualities of smoothness and transparency without being etched or forward.

Tom

[SoundMods]

Reliability can be an issue putting your speakers in harm's way of DC should you have tube failure. A friend had tried both the Futterman and Atmos-sphere amps in the past and the sound quality was "Hi-Fi" rather than musical and transparent -- and to add insult to injury the build quality was crude. He is now running SET and all the more happy for it.

[ratbagp]

Even if you can't get by on 1.5 watts, you might find the Transcendent 300B single ended OTL interesting.

http://transcendentsound.com/Tubes_and_Circuits_by_Bruce_Rozenblit.html

I heard a pair of these monoblocks at a DIY meet in England earlier this year. Even though they struggled in a large unforgiving room, their treble was amazing. The filaments are heated by a DC supply developed by this UK group that they reckon sound better than the Rod Coleman boards. You can read more about the amps at

http://tubehifi.websitetoolbox.com/post/300b-otl-with-dc-7525758

Within this Transcendent forum, ray p is the buider of the amps I heard. He also gave me a ride to the meet and it was fun to talk to him about the hobby. He uses Lowther drivers.

For more about the meet and plenty of my photos, take a look at

http://ratbagp.blogspot.com/2017/06/owston-visit-to-diy-audio-land.html

ray

[SoundMods]

Let's not confuse the current DIY version using 300Bs with the production version using series/parallel 6080s. And keep in mind that OTL amps. are push/pull in a similar way that solid-state amps are configured. And you don't want to confuse David Berning's amps with other (generic) OTLs because although his product still has transformers (tiny RF transformers) they operate in the ultra-sonic region like a transmitter modulator in broadcast radio (not quite an acurate description but you can get the drift).

Plus -- transformers are not necessarily the enemy here. It is the rest of the amplifier design that counts most when you have high-quality transformers that do not get in the way of a mediocre design. Garbage in -- garbage out.

[tomp]

David's amps have a servo to maintain low offset at the output. In addition they will automatically shut down if a problem DC output appears.

The transformers in his amps are not in the output and only run at a single frequency resulting in a vastly easier job of getting good performance. BTW, he has some very interesting ways to wind the coils that you will not see in standard transformers. Like everything else, it's all in the implementation.

Tom

[tomp]

Agree with Walt that transformers are not necessarily bad but it is exceeding difficult to design one with great performance across a wide bandwidth. When you have a single ended design it gets even worse because you have a lot of DC in the primary. I'm not a transformer guy so David can give you lots more info on the subject. In my SET I did not have to use a transformer because of the operating conditions of the VFET and also Davids very clever way of doing a floating power supply. The article on that finally got published in the June and July issues of audioXress.

Tom