Andy Evans wrote:
the copper GM70 was nicer than cheap Chinese 845's

Any experiences of how these work as low power PP amps, as 845 has done
for many users? I was thinking about 450v HT. Andy

At 450 V the 845 is a pretty crappy tube. At its rated B+ it's a
wonderful tube except it takes too much drive.

To get back to the subject of negative feedback, I firmly believe it's
very tough to make a worthwhile amp without modest amounts of NFB, but
that one should try to make the circuit as linear as possible before
applying NFB and use it in moderate amounts. Amplifiers with no NFB
(except for what is locally inherent in the devices, particularly
triode tubes) usually sound queefy and those with very high global NFB
usually sound hostile.