When were the best tube amps made?

Really great thread with lots of thoughtful responses. Thanks!

To me, the answer becomes obvious when you substitute “motorcycles” or “cars” for tube amps.  Clearly the best are being made today. But it doesn’t mean that all cars today are “better” than all cars made in 1960. It would also be logical to suggest the best amps from 1960 (and all amps were tube then) will outperform many of the tube amps made today.  This is especially apparent when based on subjective levels of performance or aesthetics. 
 

I’m interested also in the comparison to the recording side. Are all recordings made today better than all recordings made in 1960?  No, but the best recordings are being made today.

Transformers are the key element for both SET and push pull.  Even for OTL the power transformer is relevant.  Likely the best commercial winders were in Japan in the late '90s, companies like HIrata Tango and Tamura.

@rogerh113 Excellent power transformers can be made by a good number of companies here in the US.

If you take an OTL and run the ZERO autoformer on it, you wind up (if you see what I did there) with the possibility of an amplifier with much greater bandwidth than any conventional tube amp. This is because the ZERO has such low turns ratio and extremely low distributed capacitance that its bandwidth is very wide- about 2Hz to 1 MHz- wider than any tube amp made. Usually the bandwidth limitation is in the output transformer.

@atmasphere,

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…

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.