Ampeg B100R Static Under Notes

[rf7]

This amp basically has a static-type sound going on in the envelope of the note at bedroom levels. When I stop the note, the static goes away. When you play louder, you don't hear it unless you let the note decay down low enough. I've narrowed it down to the power amp section, as I can run the line out through a different amp and there is no static sound there. It's not the speaker either. I've looked at the output on the scope, but it's not noticeable there. I checked for crossover distortion at extremely low levels and I don't see it. It seems more prevalent after the amp warms up. What could this be? A noisy resistor or a noisy op-amp? It's hard to track when I can't see it on the scope. Any help would be appreciated.

[The Dude]

It sure sounds like a speaker to me (voice coil rubbing). You say in your post, however, "It's not the speaker either". How did you check it? Have you substituted a known good speaker?

[Enzo]

Agree^^^

If you cannot see it on a scope, and you only hear it at low levels or on note tails as they die off, that sure sounds like a rubbing voice coil to me.

[rf7]

You guys are right, it was the speaker. The other cab that I tested it with has a blown speaker too. Thanks!