So my JCA50 has a pretty bad sixty-cycle hum. Other amps in the same socket don't have it nearly as bad. It seems to have to do with the power section, because preamp volume only affects it very, very slightly, and it happens even with V1, V2, or V3 pulled. Is it possible that the bias is too hot? Is it just house wiring or maybe less-than-perfect amp design? Any ideas on how to solve it? I don't mind getting in there if need be, but it's easier to replace preamp tubes, for example, than to remove the whole amp from the chassis and mess with bias.
In the process, I changed V1, V2, and V3 just to see if there was any noticeable difference with different tubes, and there was not.
In the process, I changed V1, V2, and V3 just to see if there was any noticeable difference with different tubes, and there was not.
Comment