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Switchable tone capacitors?

Discussion in 'Pickups & Electronics [BG]' started by Standalone, Jan 13, 2020.

  1. Standalone


    Jan 17, 2005
    New Haven
    I upgraded a P Bass with an Orange drop. I liked it. I think it was an SX I used to have.

    So I was wondering. Are there basses out there rigged to have several tone capacitor options with different values?

    I love playing passive basses, and find plenty of variety with basic blend and tone options. But why not rig a bass with a few different “organic” tone knob responses? Just a few little switches like on those hippie six string guitars with coil taps and such. I think it’s a neat inexpensive way to widen the tonal range.

    Thoughts appreciated.
  2. I know someone used to make one. Don't have much info. I built one to figure out what cap I wanted in a pbass I was building. it's not hard. Mine was only a 3 way switch. The one I have seen being sold had way more than that on a rotary switch.
    Bassdirty and Standalone like this.
  3. ctmullins

    ctmullins fueled by beer and coconut Gold Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
  4. Tim Skaggs

    Tim Skaggs

    Sep 28, 2002
    I have a six position rotary switch with five different capacitors and one open position on a P-J bass. It works great. I bought the rotary control and multiple different value capacitors separately to keep the price down, but you can buy a pre-packaged version from Stellartone.
    Stellartone - <B>ToneStyler Landing Page & Model List

    On another P-J type bass, I have a simple single throw double pole switch with two different capacitors I can select and still use the tone pot to vary the tone.

    On my stack knob Jazz, I use a different cap on each tone control that gives me two different high cuts with each tone control and a 3rd high cut by using both together. This only works when both pickup volumes are at max.

    On a single pickup bass I have (Peavey Fury) I have a stack knob tone pot with the top knob as the tone control and the bottom knob as a blend knob between two different value capacitors. That didn’t work as well as I hoped, because the way capacitors react in parallel is opposite the way resistors react, so as I turn the blend knob from one extreme to the other, I have almost no capacitance in the middle range. I do have two different capacitor values when the blend knob is in either extreme, but the way it works, it might as well be a switch.

    I think the next thing I do will be a simple push-pull pot to select between two different caps, and then the ability to dial in the amount of high cut with the pot. No extra holes required for a switch.
    Last edited: Jan 13, 2020
    dkelley and Standalone like this.
  5. Kaplan, dkelley, kodiakblair and 3 others like this.
  6. Tim Skaggs

    Tim Skaggs

    Sep 28, 2002
    Same as what I did, but I didn’t put the resistors on the middle positions. I liked the mid peak, especially on my p-bass. My p-bass can sound almost like a Jazz on the bridge pup.
    pellomoco14 and Standalone like this.
  7. Torrente Cro

    Torrente Cro

    Sep 5, 2013
    Standalone likes this.
  8. SteveCS


    Nov 19, 2014
    Hampshire, UK
    I used a pickup selector switch to get three values out of two caps. 1, the other or both in parallel. Just ignore the greasebucket switch and the resistor, and instead wire the caps direct to ground in place of the resistor.
    Wiring Diagram.jpg
    Tim Skaggs, Bolsyo and Standalone like this.
  9. Standalone


    Jan 17, 2005
    New Haven
    Thank you all. It seems like a simple but useful idea, I was sure that it must have been done before.
    SteveCS likes this.
  10. Standalone


    Jan 17, 2005
    New Haven
    This would work in my RS924, which has had a dead preamp since 1999 or 2000.
    SteveCS likes this.
  11. Bolsyo


    Oct 18, 2015
    I'm thinking a DPDT on/off/on toggleswitch, offering 3 cap settings while taking up minimal space and it's a very easy and cheap mod. Connect the lowest value cap in the circuit as usual, and wires from each side of the cap to the middle lugs of the switch, then two other caps to be put in parallel with it and adding their value on the outer lugs. Something like this:
    Lets say a 22nF/0.022uF in the circuit, then another 22nF for the upper lugs, which in parallel is 44nF (making it close to the usual 47nF/0.047uF with cap tolerances), and a 47nF or 68nF on the lower lugs, which in parallel with the 22nF in the circuit will be it either 69nF or 90nF (close to 0.1uF).
    SteveCS likes this.
  12. SteveCS


    Nov 19, 2014
    Hampshire, UK
    In my diagram above I get three values using an on-on-on switch by having one of the positions place both caps in parallel. 0.022 and 0.047 combined give 0.069.
    ctmullins and Bolsyo like this.
  13. Phud


    Jul 2, 2017
    Gibson EB-3 has a variable rotary switch. EB3.JPG
    Standalone likes this.
  14. 40Hz

    40Hz Supporting Member

    It is an interesting and useful mod. I’m a big fan of varitone and cap switching circuits. Just don’t be surprised if you end up using only two or three of the available choices. I’d suggest limiting yourself to six or fewer cap values if you buy or build one for yourself. I’ve wired up some with more choices and ended up not using most of the available settings. A lot depends on the characteristics of the pickups(s) in your bass. I’d recommend starting with the most standard values used for guitar/bass (.022, .033, .047, .068, and .1) and then experiment with other values from there.

    And probably needless to say, you’ll find the tonal differences more noticeable if you’re using roundwound strings.
    kodiakblair and Standalone like this.
  15. Standalone


    Jan 17, 2005
    New Haven
    Three with the ON-ON-ON setup seems the right mix. But yeah I get that - my main bass has coil tappable humbuckers and there is really only one setting that I tend to use.
    40Hz and SteveCS like this.
  16. SteveCS


    Nov 19, 2014
    Hampshire, UK
    Cool. Here's a 'gut shot' that you might find useful, taken before the greasebucket and 200k tone pot were added. 500k for tone just doesn't work! DSCN3862.JPG
    Standalone and kodiakblair like this.
  17. 40Hz

    40Hz Supporting Member

    Except it’s mainly for pickup switching. It’s not a cap switcher or standard varitone control. From 1-4 the selections are: neck soloed; bridge soloed; both pickups in parallel; both pickups in parallel with midrange notch provided by a choke type inductor coil which is basically half of a transformer. You can substitute one side of a small audio transformer if you can’t find a choke in the 2.2-3.0 mH range if you want to experiment with what a choke coil does.
  18. lowfreqgeek


    Mar 15, 2010
    Tijeras, NM
    Several of my Regenerate Guitar Works basses have dual caps switchable via a push-pull tone pot. It's a nice feature, and easy to do yourself. The tone pot works like any other passive tone control, but the different caps give some options as to how it responds in the rotation of the pot.
  19. DavC

    DavC Supporting Member

    May 17, 2005
    Tallmadge , Ohio
    i bought a Varitone and stuck it in a standard pedal size box .. i think it has 13 different caps in it .. several for bass usage , most for guitar ... 1 position on the rotary switch is Bypass
  20. 40Hz

    40Hz Supporting Member

    Yeah. A friend of mine who was into modular synthesis big time said you often sit in front of a rack of expensive modules confronted by “the infinite possibilities” that are “limited only by your imagination” (as the ads say) and suddenly realize, much to your embarrassment, that you don’t really have anything to say.

    I think I’ve tried out every conceivable passive wiring scheme or trick by now. And it eventually dawned on me I really do only like a few things.

    Oh well! At least it was a fun ride trying everything out over the years. :laugh: Good thing it isn’t expensive messing around with wiring.
    Last edited: Jan 14, 2020
    MVE, pellomoco14 and Passinwind like this.

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