My ST-70 recently developed a problem in that the right channel has less high frequency extension (and perhaps less volume overall...but if so, not by much) than the left. I have traced the problem to the inside of the amp by switching the interconnects coming from the preamp, switching the speaker leads, and switching all tubes. The problem follows the speaker leads.
I re-built my ST-70 about 10 years ago with the Welborne Labs kit so it's not like it's a 40 year old in need of a complete rebuild. However, I supposed something inside has gone wrong. I'm just looking for suggestions as to where might be the best place to start looking. The Welborne mod makes it somewhat difficult to swap out parts so I'd like to keep that to a minimum although I realize that may not be possible.
I dunno....coupling caps, perhaps?
Thanks,
Joe