With transformer or OTL ?

[felixx]

Greetings!


I never had the pleasure to listen, or view an OTL (Output Transformer Less) Amplifier.
Wat do you think about Evolve amps,6c33?

I would imagine they are rare, and, very expensive. However, do they sound that good for the investment.


Which do you prefer?


Thanks!

 

[SY]

The key question with any consideration of OTL: what are your speakers?

 

[ThorstenL]

Konnichiwa,

I never had the pleasure to listen, or view an OTL (Output Transformer Less) Amplifier.

I have. The auditory results where interesting, confusing but to my ears entierly unaceptable with one exception, "OTL" Amplifiers designed to drive ESL Panels directly from the Valve Anodes, however these are specialised beasts and ESL's are not my taste in sound either....

Normal "OTL's" driving conventional speakers (irrespective mostly of sensitivity etc) usually sound initially impressive and seem initially to present more transparence and detail than traditional designs, but I find the sound ewearying and overly stressed and dynamics appear to be severely compressed subjectively (I have many times noted people actually calling this kind of effect "good dynamics", not just in OTL Amp's, I call it "bad dynamics"), plus the sound ivariably seemed to show a wearying edge (I have noted people calling this "great detail" as well).

Wat do you think about Evolve amps,6c33?

Never heard them. The only 6S33 OTL's I heard so far where Graaf, pretty middeling performance, nothing outstanding to me. The best OTL's I heard so far where AtmaSphere, but these where massive chassis with ton's of 6AS7's (you can think of 2 6AS7's as broadly equivalent to 1 6S33 in terms of output impedance, dissipation and power) and even these had a certain unpleasant edge in the long run and compressed dynamics, though less so than the smaller OTL Amp's I's familiar with.

I still tend to prefer using well above average sensitivity speakers (around 8 - 10db above the mean 87db/W/m common in commercial "HiFi" speakers) and use lowish powered SE Amplifiers.

I have been wondering what a decent SE OTL would sound like, but the demands of such a beasty in terms of numbers of output valves for even a handfull watts into 8 Ohm is scary....

And good output transformers are surprisingly transparent in the midrange and their LF problems are not as bad as may be expected....

Still, I might yet try another OTL in DIY, but not any time soon.

Sayonara

 

[Bas Horneman]

The key question with any consideration of OTL: what are your speakers?

That is also a key question with SE valve amps.

On to the original question. To twist the words of Joe Roberts.. "I've never met an OTL that I liked"

 

[SY]

Actually, some years ago, I used some original Futtermans (Futtermen?), the ones with 12B4 outputs, with Quad ESL57s. In the midrange, this was some of the best reproduced sound I've ever heard.

 

[Bas Horneman]

The last I heard were Atmasphere's with QUAD ESL63's..pretty good but too harsh for my tastes.

Best sound I ever heard was Pushpull EL34 am with some ESL's (Can't recall the brands)