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Yamaha RBX774/775 PU-switch replaced?

Discussion in 'Pickups & Electronics [BG]' started by Le Basseur, Jul 11, 2005.

  1. Le Basseur

    Le Basseur

    Mar 26, 2002
    OK,here's the story:I played last week the 775 at the local Yamaha dealer and I decided to buy one.In fact,the store had only the blue finish version and I ordered the black one...besides,the axe I tried fell from the wall support from aprox.4 feet and it had some minor finish dents and scratches,but nothing else regarding the construction-very sturdy instrument!
    Someone in this forum said once that the PU toggle switch makes a 774/775 player to feel like a guitarist :D .Personally,I'm not very happy with this PU-switching feature (though I'd may be more tolerant...the bass sounds and feels great),mainly because on my other instruments I use extensively all kind of PU blends in different proportions (via the typical blend pot),as one might expect...almost never use the 50-50 or a single PU,like the 774/775.
    My question is:did anyone tried to replace the toggle switch with a blend pot?I found somewhere the electronics' schematic and,as you can see,the toggle switch is placed before the 1st chip,not between stages.
    Any input or idea welcomed!
  2. Le Basseur

    Le Basseur

    Mar 26, 2002
    bump..... :bag:
  3. fookgub


    Jun 5, 2005
    Houston, TX
    I'm having a little trouble reading the part values on the schematic, but it looks like you could do this. Is R1 1M? The would be plenty big, I would guess, to make sure you don't lose high end response when you insert the blend pot (the impedance of the opamp is large enough to ignore).

    Use a 500k blend pot, and follow the standard blend wiring, which, I believe, is available on the stew mac website. I think this would work fine.
  4. Le Basseur

    Le Basseur

    Mar 26, 2002
    Sorry but it's the jpeg's size limitations.
    Yep,R1 is 1 Meg.
    The 500K double blend pot solution was the first it crossed my mind but I thought that someone has already done this mod so I could find out if there are some drawbacks.
    Thanks for confirming!

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