So firstly I live on an Island, I get my supplies from e-bay, and it takes a month or more to get it here. So I'm not looking for a "go buy one" answer.

What I want to do is make a violin bridge pickup using multiple Piezo elements. It is inspired by a drawing I found, probably of a Barbera. enter image description here

it looks to me like their are 4 Piezos wired in series.

1.) First question: I have some "12mm Piezo Elements Sounder Sensor Trigger Drum Disc + wire copper" are they suitable?

2.) Are Piezos directional? it looks like they are perpendicular to the face of the bridge; does it matter? It would be much easer to glue them parallel to the bridge.

this was my first prototype:

enter image description here

I cut the discs into rectangles; first I stuck them to a bridge to prove the concept, then cleaned up the long cables, and glued them to a bridge and sandwiched them between a thin peace of wood (with a cavity for the solder bumps).

It sounded good, but very hot (loud) I guess because they are in series the voltage (signal) increases for every one added?

3.) I also had a wicked hum! Obviously a shielding problem, any suggestions?

4.) last question: I have heard that having reversed polarity is a "good thing" what is that all about? I think that the new generation of Barbera bridges have 8 elements, one on each side of the string, and their polarity is opposite. This is just a guess..... anyone have anything productive to say about that?

Thanks for your time, excited to start on version 2.0

  • i am from Ukraine, read your article on piezo sensors, it was earlier, i wonder if you managed to overcome the difficulty with the background and whether the sound is dense, is there a bass? I'm also looking for this sound like Barbera or Zeta.
    – Vasyl
    Aug 15 '19 at 13:35
  1. yes pretty much any piezo will work... but it will not capture the audio good, it will sound weak(no bass), you must eq a lot or do something to correct the impedence and thats gonna take a lot of typing to explain, so do what you can with eq.

  2. piezo will create a audio signal from anything they are touching. doesnt matter what direction, it just matters that they make good contact, so yes glue them down or use some tape.

3.hum can be dealt with by twisting/braiding your wires... i see they are exposed so twist them and wrap them in tin foil(this rejects lots of emf). flourescent lights will also produce hum, maybe use an incandescent lamp while recording.

  1. reverse polarity... i have no clue sounds like when they use multiple piezos they wire them in series which should give a louder signal. if you wired them in parallel i think the one under the string will produce an audio signal but the other piezos will eat it up and vibrate/hum because they are receiving electricity from the piezo being vibrated.

Lovely work, so far. I've been working on piezo electric violins as a gigging player and engineer for thirty years and have picked up some tricks.

  1. The wire from each piezo must be shielded as soon (within 1cm) as possible. So I suggest cutting the piezo output and grafting on shielded cable.

  2. If you put each piezo In Series, you compound the already massive output impedance. The trick is to wire them In Parallel to lower the impedance. More than two piezo elements in parallel can be plugged into a Line or Mic input directly. (Series is louder but parallel matches impedances better)

  3. Place a Capacitor Inline with your Hot output lead (say, at the output jack) to kill unwanted Bass frequencies. You don't want any knocks bangs or Wolf tones to be transmitted below the G string frequency. My favourite capacitor was about 500pF. (NB: I did not ground the filter cap through a resistor, to create a high pass filter as I would lose 3db output)

Fabulous project, Best wishes from another Islander


You have quite a few questions there (and we really expect just one in a post) - but in reality they come down to two:

  • Questions 1 and 2 you have kind of answered yourself: they work, so yes, they are suitable
  • Questions 3 and 4 are inextricably linked: if it's a 50 (or 60Hz in USA) hum then you are picking up EMF interference from your mains electricity supply. Having opposed polarity has a similar effect to the wires in a balanced cable. It allows you to accentuate the signal and (mostly) cancel out noise. See for example humbucker pickups for electric guitars.

As these are piezo pickups, you want to cut out all EMF if possible, which is why the Barebera pickups have 2 opposed pickups for each string.

  • Thanks for the answer. I have sorted the EMF with shielding cut out of a high end data cable but, I am still unclear on the opposed polarity concept. There is is no magnetic field, so what exactly is in opposition? Apr 1 '17 at 19:07
  • 1
    There is a magnetic field - generated by your house wiring.
    – Rory Alsop
    Apr 1 '17 at 19:42

enter image description here

May be this could answer your number 2 question hope it helps

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