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Is a parallel wiring scheme possible

Discussion in 'Pickups & Electronics [BG]' started by Mongo Slade, Nov 3, 2015.

  1. Mongo Slade

    Mongo Slade Supporting Member

    Dec 1, 2005
    Northern New Jersey
    I have been reading a lot of threads about custom wiring jobs on basses and haven't really seen an answer to this question, so I am going to pose it myself:
    Two pickup Zon with four knobs and two mini toggles: Can the pickups be wired to a switch choosing between two discreet signal paths back to the same output jack?
    I want to wire my bass to a switch that would have one option go to an active preamp (ACG EQ-02) and the other option to a passive circuit completely bypassing the preamp, instead going to a rotary pickup selector switch, no volume knob, and a second toggle switch choosing between a couple of passive tone roll off caps. The volume knob/active blend knob would only work in the active mode with the filters. There wouldn't be any need to use both simultaneously, I just want the options.

    I will gratefully receive all feedback, as always.

  2. Crater


    Oct 12, 2011
    Dallas, TX area
    Yes, it's possible, BUT I'm pretty sure you'll need a 3-pole, double throw toggle switch to make this work, and they can be hard to find. You need a "pole" for each pickup and the 3rd pole to switch the output jack between the active and passive electronics. And please don't expect the active/passive switch to disconnect the preamp's battery, because that's a bad idea. :)

    Active/passive switch in PASSIVE mode: pickups wired directly to pickup selector switch, then to a passive tone switch. (I suggest a on/off/on toggle so you can run the pickups with no tone caps in the signal chain), then to output jack.
    Active/passive switch in ACTIVE mode: pickups wired to active blend, then ACG preamp, then to output jack.

    If I have the free time later, I may draw a schematic (not a pictorial diagram, an actual schematic) if Line6 man doesn't beat me to it. :) A competent luthier who's got good electronics skills should be able to figure this out too.
  3. You are talking about an active/passive switch. That has absolutely nothing to do with series/parallel switches.

    As for the wiring, you do not need three poles. All you need is a double pole switch. If Crater does not draw you a diagram, I'll draw one in a few days.
    Mongo Slade likes this.
  4. Mongo Slade

    Mongo Slade Supporting Member

    Dec 1, 2005
    Northern New Jersey
    First of all thank you both for responding and for the generous offers to draw a schematic. To be clearer, the rotary pickup selector would be the neck/series/parallel/bridge/mute wiring found on some Alembics and Dingwalls. Would that have to be the first thing after the pickups? Could it coexist with the active volume and blend of the ACG circuit? And, could the selection of the preamp be another node of the rotary switch?

  5. So you want there to be a blend pot for active only? That is going to require more complicated switching. Why have a blend and a pickup selector switch?
  6. Mongo Slade

    Mongo Slade Supporting Member

    Dec 1, 2005
    Northern New Jersey
    I think the blend and volume are a part of the ACG circuit that can't be eliminated. I was also thinking that having both blend for active and that range of pickup combinations for passive in two discrete signal paths would give me a really nice range of tone choices. I posted this with the hope of learning about something of which I currently know very little- so please- the more you folks can tell me about this the better; if this idea is foolish I would like to know that as well.

  7. Maybe, maybe not. Sometimes a little green pot is attached to a circuit board and has ribbon cables going to and from it, but it's just wired the same as a point-to-point passive circuit. Does your bass currently have a passive option? If not, are the pickups and preamp specifically designed together as an OEM set? If so, then you may find that the pickups aren't so good running passively anyway. Before you go modding, I'd strongly recommend trying the pickups passively to see (hear!) if they have a tone and output level that's comparable to typical fender type passives. Do this by disconnecting them from the preamp and wiring them temporarily directly to a jack.

    If that works out, then you'll need a pretty decent tech to first, find out if the blend is "active" - IOW, if the pickups are buffered individually prior to the blend pot. And then mod accordingly.

    Also, if your bass has only four holes, you'll have to think about where these extra controls are going to go.
  8. Mongo Slade

    Mongo Slade Supporting Member

    Dec 1, 2005
    Northern New Jersey
    Hmm... neither ACG or East was particularly certain that the volume or blend could be bypassed in their circuit. If I run the rotary switch right out of the pickups, then split to a three way toggle sending one choice to the preamp and the other to the passive tone switch would that still work? I assume then that the blend would only do anything when the pickup selector was set to both/parallel? And would the passive side still work if the battery failed?
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