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Piezo + magnetic = problems?

Discussion in 'Pickups & Electronics [BG]' started by SanDiegoHarry, Oct 18, 2010.

  1. SanDiegoHarry

    SanDiegoHarry Inactive Supporting Member

    Aug 11, 2008
    San Diego, CA
    I've I've heard from more than a few places that attempting to mix a piezo electric bridge pickup with a standard magnetic p'up is asking for "trouble" - - that somehow, bad things happen... :eek:

    Given that companies like bart make piezo buffers just for this very purpose, can someone offer some wisdom on this subject? Why for *would* there be a problem, provided you match your outputs, etc?

  2. Piezo bridge saddles have an en extremely high impedance, capacitively reactive output, versus magnetic pickups which have a much lower, inductively reactive output.

    Trying to mix the two mainly means that the relatively low resistance of the magnetic pickups across the high impedance output of the piezos will load them down considerably.
    You will want to use a buffer circuit to lower the output impedance of the piezos to match that of the magnetics.
  3. SanDiegoHarry

    SanDiegoHarry Inactive Supporting Member

    Aug 11, 2008
    San Diego, CA
    Yes - I get that... so, let's say I use said buffer... What's the downside? Why have I read that builders are resistant to doing this - or have I been mislead?
  4. I have no experience with piezo pickups other than my old Variax bass, so I have no idea, but I don't see why there would be any disadvantage, aside from needing batteries.

    A good buffer circuit with high headroom, a flat frequency response and a unity-gain output should pretty much sound the same as playing the piezos passive, and you could simulate the loading effect of a guitar cable with a small capacitor at the input.

    Maybe someone with more knowledge on piezo buffers can chime in.
  5. smittyxi


    Aug 24, 2010
    Boston, MA
    I have an '06 Fender "Power Jazz" with a Fishman bridge that has saddle piezo pickups. They are wired to a 9V active circuit board, each with an individual gain. The output is wired to the jack along with the standard jazz PUPs (both passive, no pre-amp).

    This might be a good reference for what you're trying to do. I haven't been able to find a diagram for the circuit but I could post a pic later if you're interested.

    Mixing the passive J pups and active piezo usually sounds full and rich when solo, but it sounds too muddy to me while playing with a recorded song. So I usually pick one or the other. I'm a bass newb so I don't play live or with a band.
  6. Jazz Ad

    Jazz Ad Mi la ré sol

    As long as you use a 2 channel buffered preamp, there is no issue in sight.
  7. JBass82


    Nov 13, 2009
    Just read your thread. I am currently working with a luthier, (Larry Lashbrook), who has his own brand of a passive piezo bridge. What of piezo brand are you using? Is it active? Are the magnetics active?

    If you are having troubles, check your wiring. I know LR Baggs needs the preamp and control to work properly, if so do you have it installed?
  8. Piezoelectric elements are passive by nature.
  9. Marcus Willett

    Marcus Willett

    Feb 8, 2005
    Palm Bay, FL
    Endorsing Artist: Bag End - Dean Markley - Thunderfunk
    Talk to Dave Wendler. Basses with piezo and magnetic setups, totally passive and works perfectly. Mine sounds great every time I use it.

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