I recently decided to do and active/passive mod to my Ibby SR500, but with an added tone control for passive mode. I wired everything according to post #14 of this thread: Bartolini active/passive tone control
So, in order to do this mod, I had to replace the stock 25K volume pot placed after the pre, with a 250K push pull. The problem I'm having, is that after about 20 minutes of playing (with plenty of active/passive switching action
) the active mode slowly becomes quieter and quieter, until the active mode is quieter than the passive mode. I can unplug the battery, leave it for a while and the plug it back in, and the whole process repeats itself.
Am I right in assuming that the pre doesn't like having a high value pot placed after it? Does anyone have a diagram that places the volume knob before the pre, rather than after it? Am i even on the right track (this is most likely
Btw, I'm running the stock (passive) Bartolini MK1 pickups and the Ibanez EQB3S pre.