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Ibby SR500 passive mode w/tone control

Discussion in 'Pickups & Electronics [BG]' started by Jordan S., Aug 24, 2012.

  1. Jordan S.

    Jordan S.

    Mar 25, 2012
    NSW, Australia
    Blacksheep Effects Pedals
    Hey Guys,

    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: http://www.talkbass.com/forum/f38/bartolini-active-passive-tone-control-703202/

    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 :smug: ) 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 :p)

    Btw, I'm running the stock (passive) Bartolini MK1 pickups and the Ibanez EQB3S pre.
  2. Jordan S.

    Jordan S.

    Mar 25, 2012
    NSW, Australia
    Blacksheep Effects Pedals
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  4. JustForSport


    Nov 17, 2011
    Could be that 250k pot is prob after pre.
    An add'l vol/tone stacked pot for passive side may be req'd.
    This switch separates source, but may 'pop'.
    Maybe someone can further this basic sketch. Active -Passive Switch.jpg