Hi there, I recently got an old preamp that came out of a P bass special from 1983. I placed it into a 5 string bass that I built and it sounds good and very quiet. I used Seymour Duncan quarter pounder Jazz bass pickups which are much hotter than the original P bass pickups from Fender. The only problem that I have is that it has got a boomy bass sound. Obviously the preamp was designed for a four string bass and not for a five string bass. Now, I can help myself with a soldering iron. but I am not an electronic expert by any means. I have got a copy of the schematic of the preamp and would like some help from you guys. I'm sure there's a way to change one or two components to reduce the gain of the bass frequency, maybe smaller caps or resistors but you guys must tell me which. Any help would be appreciated. Thanx.
Of course the tone controls should be set flat (or bypassed/removed, which would also give higher gain).
The value of C1 (battery bypass) seems small, I would use at least 100uF.
I'd directly couple Q4 and Q5, so all the parts between them could be removed: C10, C11, C12, C13,
and also remove the three resistors connected to them that are too hard to read 464k, 21.5k, 21.5k.
With these changes, the value of R17 may need to be adjusted for 5V DC at the Q4 collector.
The value of C1 (battery bypass) seems small, I would use at least 100uF.
I'd directly couple Q4 and Q5, so all the parts between them could be removed: C10, C11, C12, C13,
and also remove the three resistors connected to them that are too hard to read 464k, 21.5k, 21.5k.
With these changes, the value of R17 may need to be adjusted for 5V DC at the Q4 collector.
