post CBS Silverface 6AQ5 amp from 1973,
unmolested so we left out all the mods people do like bypass the input cap , increase cathode bypass caps, add a DeLuxe tone circuit, remove the .047 cap from across the mains,
you can do that stuff but souping up a sparrow hawk does not make an eagle, the above mods add a little but not much, plus the small cathode bypass caps and input cap are there to protect the weak speaker from bass,
this is the only git amp i have seen with an innerstage transformer. we added a long tail to the same amp a while back and it cranked.
the power lytics were fine so we left them.
there are no screen resistors, and only a 1K between B+ and screens, so the screens sit higher than the plates, no big deal, these tubes are cheap, and we can squeeze 8 watts out of a cathode bias so that is cool. the tubes actually still had some life in them so they get to stay.
one thing we noticed is that there was some 'fuzz" on the waveform, this is RF from tube oscillation, so we stuck a couple of .01/1KV caps from plate to cathode and it cured the problem and the amp sounds better.
these can be easily removed as they go into spare holes on the sockets if the customer wants to go back to dead mint.
unmolested so we left out all the mods people do like bypass the input cap , increase cathode bypass caps, add a DeLuxe tone circuit, remove the .047 cap from across the mains,
you can do that stuff but souping up a sparrow hawk does not make an eagle, the above mods add a little but not much, plus the small cathode bypass caps and input cap are there to protect the weak speaker from bass,
this is the only git amp i have seen with an innerstage transformer. we added a long tail to the same amp a while back and it cranked.
the power lytics were fine so we left them.
there are no screen resistors, and only a 1K between B+ and screens, so the screens sit higher than the plates, no big deal, these tubes are cheap, and we can squeeze 8 watts out of a cathode bias so that is cool. the tubes actually still had some life in them so they get to stay.
one thing we noticed is that there was some 'fuzz" on the waveform, this is RF from tube oscillation, so we stuck a couple of .01/1KV caps from plate to cathode and it cured the problem and the amp sounds better.
these can be easily removed as they go into spare holes on the sockets if the customer wants to go back to dead mint.