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Thought on OTL tube amps

Just curious....how do these sound/perform compared to tube amps with transformers? Why do you prefer one or the other? Any particular brands of OTL amps you would recommend listening to? You can see my system on my tag here...listen mostly to rock and roll with a smattering of jazz and a bit of classical once in a while. The next stop on my amplifier adventure is an OTL model, and I have no intention of trading it for either SET I currently have, as I'm very happy with both. One of the ways I enjoy experimenting with different "sound" is by switching up the amps. Just trying to solicit some opinions, of which I know there are many strong ones here at A-Gon. Thanks in advance!
afc
almarg's avatar
almarg
9,670 posts
 
Using the Zero nullify an OTL status.You already get rid of transformer then put new Transformer?Whats happening? going in circle?

Xonex77, your question is a logical one, but there is a good answer to it.  From the FAQ at the website for the Zero:
What is the difference between the ZEROs autoformer and a typical tube amplifier's transformer?

The ZEROs have a few advantages over "typical" tube amp transformers:

A) The music comes out on the same winding wire that it goes in on so the music does not have to pass from a primary winding to a secondary winding.

B) There is no DC current to contend with. When a transformer is made to accommodate a DC field, its audio transparency is compromised.

C) The impedance ratio is very small (16 ohms to 4 ohms, compared to a few thousand ohms to 4 ohms). This simply means that it is much easier to achieve things like, frequency response extremes, than with a "typical" tube amp transformer. The ZEROs sport a frequency response of 2 Hz to 2 MHz.
All transformers (and autoformers) are not created equal!

Regards,
-- Al
cal3713's avatar
cal3713
1,421 posts
 
Thanks for posting Al.  I should just start reading every post of yours so that I continue learning the science behind the music.
larryi
4,357 posts
 
If the Berning folks might be stretching it a bit to call their amp an OTL, what about companies, like Tenor (I believe), that put out a solid state amp that they described as OTL?  This was absolutely true, but, aside from a few solid state amps like models produced by McIntosh, all solid state amps are OTLs (low output impedance of transistors makes transformers unnecessary).

By the way, all of my amps are FCL (flux-capacitor-less).
almarg's avatar
almarg
9,670 posts
 
By the way, all of my amps are FCL (flux-capacitor-less).
I suspect that they'll perform best with contemporary music  :-)

Chris (Cal3713), thanks for the nice comment.

Best regards,
-- Al
 


atmasphere's avatar
atmasphere
12,190 posts
 
If the Berning folks might be stretching it a bit to call their amp an OTL, what about companies, like Tenor (I believe), that put out a solid state amp that they described as OTL?  This was absolutely true, but, aside from a few solid state amps like models produced by McIntosh, all solid state amps are OTLs (low output impedance of transistors makes transformers unnecessary).

I remember when Allied used to write up the receivers in their catalog back in the early 70s. They referred to their circuits as ITL/OTL and maybe with good reason at the time. A lot of solid state amps back in those days employed input transformers as phase splitters to the output section!

These days though OTL generally refers to a tube amp, not a solid state amp as its no big shakes with solid state in that regard.
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