What is the best OTL out there?


Hello. I've always been curious about OTL amplifiers, but never tried one except for the very unusual (and wonderful) Berning Siegfried, which was both SET and OTL. I wonder if there is an agreement as to which OTL currently in production can be considered to be the best. Ciao.
ggavetti

Showing 5 responses by atmasphere

However I took atmospheres comments to apply to solid state as well but I could be wrong about that as I don't have much knowledge about solid-state here.
My comments include solid state and class D as well. All amplifiers have lower distortion into higher impedances and this always translates to smoother sound with greater detail. Given that some solid state amps are really expensive, the only explanation I have for the persistence of low impedance speakers is that speaker designers are often not that aware of how the speaker/amplifier interface affects the sound and the performance of the amplifier, and by that I mean **any** amplifier.

Of course, when you put an OTL on higher impedance speakers, that's when the magic happens and on such speakers I've yet to hear any competing technology sound better. But of course I make OTLs- I could be biased just like the power tubes in an amplifier are.

I love that Bernings amps get picked apart yet when someone says that they use an autoformer after the output of a OTL the only thing heard is the crickets.
I don't think anyone picks apart the Berning- its an excellent amplifier, a brilliant design, with excellent reviews and isn't an OTL.
As a separate issue, using an autoformer on an OTL allows you to solve problems- usually one where the speaker desired is simply unsuitable for the amp otherwise. We have a lot of customers here in the Twin Cities that like to use Magnaplanars with our amps, and especially with our smaller amps, the autoformers are a good idea. A good number of people that don't have OTLs also use the autoformers, including people with solid state amps, for no other reason than it sounds better. This is true because all amps have lower distortion when driving higher impedances. 

Whether an amplifier is an OTL or not is an entirely different subject from how it sounds. Personally while we make OTLs, I don't see other OTL manufacturers as the competition so much as just other amplifier manufacturers in general.
Most OTL  are not producing enough plate dissipation for a pair of tubes,Imagine for a pair of 6c33c tube with max.of 60 watts plate dissipation can produce more than 25 watts class A of power, 3 x of 300b output in SE.
Its not a matter of plate dissipation, its a matter of output impedance. For some reason people really do want a low power OTL, but what happens is as you decrease the number of power tubes more and more of the total power generated by the output section is absorbed by the output section itself. So if you build a bigger amp its more efficient and the individual power tubes run cooler.

Not trying to change the subject, it just seemed like all the posters here would be the ones to ask. I would like to get recommendations as to whether anyone uses an OTL amp with Quad 57's. I bought a pair of these to try, after all these years, I have never heard a pair so I figured it was time to try them out. I have read on some other forums that a lot of the recommended amps mentioned here were if I remember correctly also recommended for the Quads. Does anyone have any experience with this pairing?

Quads and OTLs have a history together going clear back to the 1950s. We have a lot of customers that use our amps with ESL57s and ESL63s which are good speakers for OTLs due to a fairly benign impedance curve.
I hope it arrives in good shape!

Our Michigan dealer has Paragons (if I recall right, the big one and the little one). He says our amps work fine with them. I've not experienced it myself- but you could ask him- he's the guy that makes the Classic Audio Loudspeakers.
There's some out there who designed and build their own  OTL that uses better tubes like KT88/120/150,,300b,,VV52b,,even 211 / VT 4C can  be used and  they are more efficient than the ones  on the market today.
This statement is false- there are no OTLs based on any of the tubes listed above.