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Cut lows from pickup with capacitor?

Discussion in 'Pickups & Electronics [BG]' started by berklee46, Nov 11, 2018.

  1. berklee46

    berklee46 Supporting Member

    Dec 19, 2000
    Admittedly, I’m fairly ignorant at understanding wiring and electronics, but experimenting with some pickup changes recently got me thinking.

    Just to give some more tonal options, and maybe tame the power of a Musicman pickup in series mode for example, I wondered if the lows directly from the pickup could be cut so the sound currently heard with the bass EQ set at 0 (flat) would actually be the bass EQ turned halfway up, essentially making the bass control a cut/boost instead of boost only?

    I guess this would make the passive sound of the pickup less bassy, but if the bass was used with the active preamp all the time, this wouldn't matter.

    I was able to find this on the Stewart-MacDonald site and believe this better explains what I'm talking about:

    Here's an idea you may want to look into: a "treble bypass cap." Here, a capacitor bridges the input and output lugs on a volume pot; this allows the high frequencies to bypass the pot and stay in the signal. Lower frequencies are blocked by the cap, and are controlled by the pot.


    Has anyone here done this and been satisfied with the results?

  2. G&L does it as well a Rickenbacker:

    The ones I've seen are usually around 2.2 nanoFarads (with a pot to adjust) or 4.7 nF (without an adjustment).

    You could put in a trimpot to dial it to taste:


    The higher the value of the cap, the lower the cutoff frequency will be.

    G&L uses a 2.2 nF with a resistor, but Rickenbacker uses a 4.7 nF w/o a resistor (for the bridge pickup):


    note C3
    PawleeP likes this.
  3. micguy


    May 17, 2011
    I’ve done a lot of passive filtering in basses, but I simulate everything before I build it. The kind of things you’re talking aboit aren’t easily explained unless you know the whole circuit - pots, loading caps, tone caps, cables, etc. My Avatar might give you some idea of the things I do - not necessarily simple.
  4. berklee46

    berklee46 Supporting Member

    Dec 19, 2000
    Thanks guys, I appreciate you jumping in to help.

    Keeping in mind my limited ability to only be able to do wiring if I have a color coded picture designed for a child to understand If I wanted to try this with a Musicman pickup with the switch wiring below, then through a Sadowsky 2 band pre, where would the cap go?


  5. If it's active all the time you don't really need it.
    If you want it to cut bass before the preamp then put it between the + from the switch & the preamp.

    If you only want it to operate when the bass is switched to passive mode, you'd need to put it between your active/passive switch & the output jack.
  6. berklee46

    berklee46 Supporting Member

    Dec 19, 2000
    I’d be looking to try it with both active and passive, but if it’s simpler, I’d try it with active only.
    The Sadowsky pre is a powerful boost so a hot pickup like the Bigman or even the Bartolini Quad-coil can really get overwhelming with a minor bass boost, and WAY too much to run in series.

    I figured this was a way to make the bass EQ more useable rather than left flat all the time.

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