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Active/Passive Project Bass, Help??

Discussion in 'Pickups & Electronics [BG]' started by FreakyLowBass, Mar 7, 2013.


  1. FreakyLowBass

    FreakyLowBass

    Jan 15, 2012
    Essex, Ont
    I'm trying my hand at building a bass from scratch(or at least everything but the neck kind of scratch). I've done my designing and chose the different woods and hardware, but I've just thought of something today that I may have planned incorrectly. I'm trying to build a 5-string bolt on neck style bass with one passive EMG pickup and two active EMG pickups. Each pickup would have an independent volume before converging into the EMG BQC control and finally into a master volume pot before the jack. Would this be an issue? I'm aware that there will be a difference in volume between the active and passive pickups but would there be any issues bring the signals of the three pickups together in this fashion?
     
  2. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    You can't mix active and passive pickups like that. The reason is that the low output impedance and low value pots of the active pickups will load down the passive pickup.

    Here's what EMG says:

    Can I mix EMG’s with passive pickups?

    It is possible to mix EMG’s with passive pickups. There are three possible wiring configurations; one is better than the other two. Use the high impedance (250K-500K) volume and tone controls. The problem is that the high impedance controls act more like a switch to the EMG’s. The passive pickups, however, will work fine. If you have a guitar with two pickups and two volume pots, with a three-way switch, there is another alternative.

    Use the 25K pots for the EMG, and the 250K pots for the passive pickup. This way you can use one or the other with no adverse affects, but with the switch in the middle position the passive pickup will have reduced gain and response.

    Use the low-impedance (25K) volume and tone controls provided with the EMG’s. The problem here is that the passive pickups will suffer a reduction in gain and loss of highfrequency response.

    This is the best alternative. Install an EMG-PA-2 on the passive pickups. There are two benefits to doing this. With the trimpot on the PA-2, you can adjust the gain of the passive pickups to match the EMG’s. The PA-2 acts as an impedance matching device so you can use the low-impedance EMG controls (25K) without affecting the tone of the passive pickups. You will also be able to use other EMG accessory circuits such as the SPC, RPC, EXB, EXG, etc. For this application, we recommend ordering the PA-2 without the switch for easy installation on the inside of a guitar.
     
  3. FreakyLowBass

    FreakyLowBass

    Jan 15, 2012
    Essex, Ont
    Impedance seems to be the main issue here(please correct me if I'm wrong). Hypothetically, if I were to use an active preamp volume(if there is such a thing) on the passive pickup that had 25k rating, would I be able to wire this thing the way I had said earlier?
     

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