Could someone help out with a wiring diagram?

Discussion in 'Pickups & Electronics [BG]' started by hstiles, Jul 28, 2001.

  1. I have an old 5 string bass with P & J style EMGs. The onboard preamp is awful, so I want to remove it and switch the bass to a 2 volume, 2 tone layout with 18-volt circuit.

    Does anyone have a circuit diagram available - I'll need to replace all of the pots, so if you know exactly which part number is best to replace them that'll be great.

    Thanks a lot for your help.
  2. 18 volt circuit? would that require two 9 volt batteries? I don't think i have ever seen that on a bass setup... or would the on board circuitry step up the voltages? I have never heard of this.

  3. Nino Valenti

    Nino Valenti Supporting Member Commercial User

    Feb 2, 2001
    Staten Island NYC
    Builder: Valenti Basses
    I recomend you go w/a Aguilar OBP-1 pre-amp. It sounds really nice. It is an 18V pre-amp. Also, the EMG BTS pre-amps are really nice & you can run it @ 18 volts.
  4. uh ? dude..
    there are even basses with 3x9-volt batteries..

    for example.. the Ibanez BTB has 2 9-volt batteries.
  5. Luis Fabara

    Luis Fabara

    Aug 13, 2000
    Ecuador (South America)
    Audio Pro - Ecuador
    I believe Its time for manufacturers to start using Phantom Power on basses.
    Wouldnt be great to stop worrying about the batteries and even have 48 VOLTS!!!

    Isnt XLR a better option to a Plug?
  6. Aguilar stuff isn't easy to come by in England. Also, I don't want to fork out for the OBP-1. If I did, I certainly wouldn't 'waste' it on this bass - it'd find its way into one of my 2 Ergodynes.

    The EMGs have built in preamps, albeit without the extra tone-shaping capabilities, but that isn't a problem - I usually set the EQ flat.
  7. Wait a minute..if you want an 18V preamp won't that mean you need 3 batteries; 9V for the pups and 18V for the EQ? Or do you want the whole thing to be 18V(9V preamp, 9V pups)
  8. Luis Fabara

    Luis Fabara

    Aug 13, 2000
    Ecuador (South America)
    Audio Pro - Ecuador
    PanteraFan, I believe they share the same power input.
  9. I don't really get how that would you can have active pups with no EQ that require a single 9V battery. That works out at 4.5V per pup. Adding a preamp logically dictates that more power is required. Otherwise you would have all three active components drawing 3V each.
  10. Mark Gollihur

    Mark Gollihur Supporting Member Commercial User

    Jul 19, 2000
    Gloucester County, NJ
    Owner/President, Gollihur Music LLC
    At NAMM I picked up the EMG wiring book that they were giving out. Give me a little more info as to what you have and what you're trying to do.

    My main axe has 2 EMG soapbars, the BTC circuit (with Master Volume/Balance rather than Pickup 1 Volume/Pickup 2 Volume) and runs on 18 volts. I recommend this setup highly - it's super easy to set up, flexible, and cuts through in the mix. I've always been happy with my EMGs and have no intention of changing out the electronics in my bass.

    Pantera Fan:
    The circuits share the multiple batteries; the voltage is 18 volts at each part of the setup. AFAIK, voltage doesn't "halve" with each additional piece, but milliamps probably do. This means that although the voltage should still be 18 volts all around, the batteries don't last as long as they would without the preamp - kind of like plugging two lamps into the same extension cord - the first lamp doesn't dim when you turn on the second one, but your electric meter spins twice as fast... Keep in mind, I'm no electronics expert - someone pleae correct me if I'm wrong.

    EMG active pickups and electronics are designed to be powered by as many as 27 volts (three batteries.) For more information on running EMG circuits at 18 volts, check out my how-to article on the subject.
  11. ahpook


    Jul 13, 2001
    This is right. The pickups will be wired to the supply in parallel, so you'd see a constant voltage across each one, but the current may vary.
  12. Ah, I thought the pickups would be wired in series, adding the resistances of both pickups together. This would have a somewhat detrimental effect, as more voltage would be required to overcome this resistance.

    Are all pickups(active and passive) wired in parallel, or are actives wired parallel and passive in series?

    If I am correct in my thinking, if you wired an active EQ in parallel with passive pups, the pups would receive a lot of voltage(say 18V on an 18V preamp) I would guess that the passives could be wired parallel both going into separate inputs on the EQ...thereby enabling the blend function.

  13. ahpook


    Jul 13, 2001
    if you wire anything in parallel, the supply voltage will appear across each component. (voltage is constant in a parallel circuit, current is constant in a series one...)

    i'd check to see if you pickups would be happy with 18v

  14. Well, you can't really check the specs on unbranded pups.:D
  15. ahpook


    Jul 13, 2001
    ahhh - problem !

    well, i suppose you could just wire them up & see what happens if you put 18v across them.....but they're your pickups :)
  16. I just looked at some wiring diagrams on, and a passive J-bass has each pup wired to a separate pot, with those pots going into the tone pot. Stands to reason that a passive P-J setup will be like this.

    The active P-J diagram is the same, just with each up wired into the power source spearately as well.