When were the best tube amps made?


And what were they?

1980's Audio Research need not apply. 

erik_squires

In a talk Roger Modjeski (Music Reference, RAM Tube Works) said Tim de Paravicini (EAR-Yoshino) told him he could tell what a tube amp sounded like by looking at it’s transformers. Both Roger and Tim extensively studied the art and science of transformer design, and wound their own.

not sure whether Zero Autoformers are really zero cost. I used them on a Graaf GM20 about 15 years ago and while bass was significantly tightened, the overall SQ lost pizzazz. It felt a bit like a Ferrari on Qualudes…

@antigrunge2 The result depends largely on the interface of the amp to the load. In our case, it works really well if the load is lower than the amp is comfortable with. There are tradeoffs if part of the load (like the mids and high) are easy to drive while the woofer isn't. However sometimes in that case, if the speaker can be bi-wired, you can run the ZERO just on the woofer to correct the impedance and run direct on the mids and highs.

If the amp uses feedback, as in the case of the Graaf (IIRC) then its a good idea to have the feedback at the output of the transformer, which would take some work... So its not a cure-all solution, but it is one that can be very effective if the stars align.