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Passive piezo blending?

Discussion in 'Pickups & Electronics [BG]' started by Will_White, Feb 8, 2016.


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  1. Will_White

    Will_White

    Jul 1, 2011
    Salem, OR
    I have an acoustic bass that I'm adding a piezo out two to and I'm wondering if I could blend the signal from two peizos like with two magnetic pickups.
     
  2. JustForSport

    JustForSport

    Nov 17, 2011
    Don't know why not-
    Some piezo elements in strips are all connected together inside the strip with one signal (and ground) wire out.
    Other bridges with separate saddles collect the signals together in a PCB 'manifold' collector, then one signal/ground out to the buffer/preamp.
    Some Fishman designed (in Washburns among others) and Ibanez (like EDA 905) keep the element's signal separate 'til they get to the buffer/preamp board where they have trim pots for each signal.
    What the pot value would have to be for a blend (or vol/vol) between the 2 piezos if placed before a single buffer/preamp....?
    If each piezo went to its own buffer/preamp, then the outputs from those could be blended.
     
  3. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    passive piezo blending?

    nope.

    piezos don't mix with magnetics without active buffers between both sources.
     
  4. I think that he is talking about mixing two different piezo signals, though. There would be no magnetic pickups.
     
  5. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    oh yeah, i think you're right!

    hmm, essentially two capacitors in parallel, it should work; it would increase low end i think.
     
  6. arctur

    arctur

    Nov 13, 2015
    Cologne, Germany
    If you would like to check out a readymade solution, check out the Richter BassXX preamp. It's a solderless system that can be had with a passive blend as well as a piezo mixer. I am probably gonna install one of those at some point...
     
  7. Piezos (even same size, same shape) vary a great deal in electrical spec, plus the positioning of a piezo will greatly effect its output. I'm guessing that one piezo is under the bridge. Where are you puting the other?

    Caps in parallel are like resistors in series. If you simply switch them together (passively) in parallel, I think you'll get a bit of a volume drop as you are essentially doubling the (already huge) output impedence of your passive piezo bass.
     
  8. JustForSport

    JustForSport

    Nov 17, 2011
    Bartolini makes a 2 input/2 output buffer that could go to a blend pot.

    Most likely going to have to use a buffer or dbl buffer (active) to get a decent signal out.
     
  9. Will_White

    Will_White

    Jul 1, 2011
    Salem, OR
    I'm planning on doing one under the bridge and one on the soundboard into a buffer with a 10 or 15 Meg input impedance no magnetic pickups. I originally thought about using a switch, which it looks like that might still be the best option, but I thought I'd ask about piezo blending, I'm not interested in a pre-made solution.
     
  10. JustForSport

    JustForSport

    Nov 17, 2011
  11. Cool. There's a guitar company here in Australia that puts a piezo element in one of the cross-braces of the face.

    If you had planned on making a fet buffer, well I'd recommend making two. And as justforsport said, having adjustable gain for at least one will be handy.

    I'd also be prepared to test phase of the two elements so that when combined you get the fattest tone.
     

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