Intermittent change in sound

[smithanh]

Recently, I've developed a significant change in sound in my left channel after playing a couple albums. The sound gets louder, brighter with a drop in bass output and with more glare. If I turn the seduction off for a while, then turn it on again, the same pattern repeats. I suspect I've got a bad solder joint, but I was hoping someone might be able to give me some direction about where to start locating it.
Thanks as always

 

[Paul Joppa]

It's somewhere in the RIAA equalization circuit, in or around the 0.033uF cap.

There's a slimmer chance the tube is going bad - swap tubes to check that.

 

[smithanh]

Thanks Paul, I unclipped the C4s board and cleaned up some extra solder that I couldn't see. That did the trick!