Piezo polarity and multiple piezos

Posted by David L. on July 22, 2010 at 1:46pm

Hi,

 

I recently came across this on the www http://www.prodigy-pro.com/diy/index.php?topic=34505.0

basically the people here are saying that because the polarity maybe different on different discs when wired together they may cause signal cancellation.

 

Any clever person here know if you can detect this difference in polarity with a cheap multmeter and if so how? Or would I need a more  expensive  piece of kit?

 

Thank you,

David 

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Replies

  • David L. August 9, 2010 at 4:55pm
    I have found the following using piezos taped to a strat copy body around the bridge and put through a 10W amp

    1. No difference in sound between between 25mm and 35mm discs.
    2. Changing position of the disc did give a slightly different sound (stick it on the high e string you get more treble and stick it on the lowE you get less treble - no surprise there)
    3. No difference in sound between 1 and 2 or 3 piezos wired in parallel
    4. intentionally wiring 2 piezos black/red to hot and red/black to earth didn't affect the sound (no sound cancellation to my ear)
    5. 2 piezos wired in series sounded poor compared to a single piezo or 2 in parallel.

    (please note this is only my view and others may have diferrent opinions which I would gladly like to hear)
  • MichaelS Country Boy Guitars July 23, 2010 at 8:27pm
    OK, if there is no polarity then it shouldn't matter if they are wired parallel or in series?
  • jim July 23, 2010 at 11:35am
    "Piezo transducers produce alternating current" Test one, it depends on which way the ceramic is flexed/compressed that sends the positive current . and that current alternates from side to side depending on the flex/compresssion of the ceramic. you all figure it out, im done
  • Grizz July 23, 2010 at 10:18am
    If piezos were AC current than everything in the circuit would also be AC current. That would mean it doesn't matter how you wired anything, which of course is incorrect. There are positive and negative poles to all of it.
  • jim July 22, 2010 at 11:32pm
    That thread is so full of B.S. Piezo transducers produce alternating current. So polarity alternates from lead to lead.
  • MichaelS Country Boy Guitars July 22, 2010 at 4:04pm
    Interesting read, I have no idea how to check the polarity either, would be nice to know, I just made 2 double piezo pickups and they sound good, maybe I got lucky or maybe it doesn't matter with only 2? Anyone know?
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