"Jim Lesurf" wrote in message


Well, I don't know the design of SET amp you refer to, so can't
comment on it specifically. However when I had a student build a
transistor SET amp some years ago the expensive and difficult part
was the o/p transformer. This is a bit easier in some ways than for
valve as it didn't have to isolate very large voltages, and didn't
have a large turns ratio. But you still end up requiring a
significant (expensive) transformer if you want it to work OK even
down to LF.

I don't know if I still have a copy of his project report. When I get
a chance I'll have a look for it. My (perhaps unreliable)
recollection is that the performance was limited by the transformer
not by the choice of gain devices. Hence such theoretical
'simplicity' can become quite complex and costly to attain. Looks
simple on a circuit schematic, though. :-)

Yes, that is a big concern of mine as well.

One of the nice things about push-pull amps is the flux cancellation in the
output transformer. Of course no output transformer is usually even better.