I finally got around to modding my BC30 last night. I cut C3, C5, and C6, and also changed out R15 and R21. What I was lacking was the electrolytic cap needed to change C15, and also realized the board will have be removed to replace it, so I skipped C15, but I would like to know what effect dropping the value from 22uF to 2.2uF has.
The results are largely positive, the amp sounds looser, with a little more sag it seems, and fuller. The drive and interactive channels are vastly improved, offering a lot of tonal variations, and the tone stack functions within the normal ranges with those channels. I was getting some low end thump from the interactive channel that was very impressive.
The issue is with the clean channel, which is quite dark compared to the drive channel. I'm having to turn the treble up to 9 and the bass down two 2 to add any bite to the tone. The tone is also fuller like the other channels, but I'd like to figure out a tweak to balance the clean channel out. As is, it will be impossible to switch between channels without adjusting the tone controls. I wonder if I could reconnect one of the caps using a lower value and achieve my goal--anyone have an idea on how to?
As of now there are stock power tubes and speakers in my BC30, with Tung-sol reissue preamp tubes. I bought a set of Tung-sol reissue 5881 tubes to go in it, and I may try it with the Red Fang speakers in my Black Pearl. The sound of the wound strings through the Lady Lucks is pretty good, but the top end sounds flat to me, so new speakers are a definite must.