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3 band passive tone wiring

Discussion in 'Pickups & Electronics [BG]' started by IWieldTheSpade, Feb 12, 2014.

  1. IWieldTheSpade


    Mar 15, 2010
    Hi all,

    I'm interested in putting a 3 band passive circuit (treble cut, bass cut, mid notch) into an upcoming project but I've been getting a little muddled in how things all go together within it - I've only dealt with wiring standard treble rolloff controls before.

    Attached is a schematic of where I'm at currently, I was wondering if I could get some critique of if I'm on the right track or not from some of the more knowledgeable that float around here. No values are assigned yet, I still haven't figured out what frequencies I want to set each to.


    Attached Files:

  2. Just playing with your schematic on LTspice IV, the volume is going to effect your bass cut quit a bit but think you're on the right track. Put the volume at the front it will effect your high cut.
    I'm more of a low-pass filter, twin T notch filter on a switch type of guy.
    I'm really not mocking you, I'm a nerd.
  3. IWieldTheSpade


    Mar 15, 2010
    Thanks for having a go through with it, I should really pick up some software for circuit analysis. In absence of my own at the moment, how did the volume affect the bass cut? I was also planning on sticking two volume pots before the circuit to blend each side of a humbucker, along with a series/parallel switch. Will that cause too much issue with the tone controls?
  4. Grissle


    May 17, 2009
    Rather than the three band maybe consider a Treble/Bass cut solution ala G&L, plus a multi cap switch or Tonestyler. This would be more useful IMO, and pretty simple also.
  5. Shifts the corner frequency higher when volume is lowered.
    Volume before the high cut (low-pass filter) will shift your LP-filters corner lower when volume is lowered.

    I suggest one of these http://www.allparts.com/EP-0920-000-6-position-Rotary-Switch_p_1345.html on your bass and get a (off-board) pre-amp, I use a dual 31 band eq with HP and LP filters. I know, I know, :rolleyes: overkill.

    I don't do much passive any more, except distortion :smug: I love me some passive distortion.
  6. Yeah, the reason why no one ever does this is that the volume drops are too significant for it to be worthwhile. I would use active equalization, instead, but that's just me.
  7. Grissle


    May 17, 2009
    The volume drop is one of the reasons I made my suggestion. The G&L setup is pretty versatile and the bass cut works nice in boomy rooms.
  8. uOpt


    Jul 21, 2008
    Boston, MA, USA
    No, the problem here is that the high-impedance pickup has its own electrical properties modified by all the jazz hanging off the end now.

    Passive pickups are highly sensitive to load capacitance and resistance in particular.

    The only non-standard tone control that makes sense with passive pickups is a LCR network aka Ritchie Blackmore or Bill Lawrence's Q-Filter. That removes impedance from the circuit (essentially from the pickup) without changing other properties. So you can get effects you cannot get with more or less wind on the coils (more wind always adds all properties).