How to make a piezo pickup

Discussion in 'Amps, Mics & Pickups [DB]' started by ToneRanger, Nov 11, 2005.

  1. I've figured out how to make a piezo that sounds great, doesn't buzz or hum, and costs under $5.00. A few people were asking about them, so I've put some details here:
  2. I'm not a DB player, but that's pretty cool!
  3. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    This is like Popular Science for Double Bass pickups. All you need is FDecks little amplifier with you're favorite off the shelf speaker and you're good to

  4. Brilliant!

  5. ToneRanger

    Is the Copper Foil Tape 1/2 in width?

    Great idea.

    I ordered the piezo tabs.


  6. No, I have a roll of 1" tape. It allows for some overhang each side, and I trim the whole thing with scissors when it's together, so it doesn't matter if I'm a bit sloppy sticking the pickup in. I use a continuous piece that folds to make top and bottom shield.
  7. WalterBush


    Feb 27, 2005
    Yuma, Az
    I've made similar devices with Radio Shack Piezos. I'm anxious to try these sensors, and already ordered some. Thanks!

    I don't have any pictures, but I've had good results from dipping the piezos in liquid electrical tape a few times to build up thickness. It's a good protective layer with no heating involved, and should be available in the electrical section of your local hardware store. Excessively thick coatings start to roll of high-end response, which may be considered a good thing.
  8. I also ordered some of those transducers. I soldered a cable & jack to mine & started experimenting. The transducer is extremely sensitive to touch, rub, or blow on, etc. but doesn't pick up the vibrations of my bass strings very well at all. I tried under the bridge & in the bridge wing with a piece of cork. It doesn't seem to pick up the proper frequency. Could it be that I need to reverse the polarity on the transducer, or that I have a bad one?
  9. Hmmm... if it's working at all, it should be working on your bass. Polarity is not big deal if you're using a single one - just flip it upside down to reverse the phase.
    I've found under-bridge mounting by far the best sound and output, but getting the bridge seated evenly was tricky until I tried using a shim of cork gasket material under the piezo.
  10. I did a little more experimenting last night. It seems that the preamp needs to be as close as possible to the piezo. I was connected to the preamp through an 18' cord & all bass was lost. Mounting the preamp on the bass solved the problem.
  11. That makes sense. The lead on my pickup is only 6 inches. The quality of cable makes a big difference too - I started out using cheap rubbish and found things improved when I got some very good, very light Mogami cable - the sort they use on lapel mics. A local pro-audio repair guy is happy to sell it by the meter.
  12. jonas


    Dec 9, 2003
    Frankfurt am Main/Germany
    Lando Music (Germany)
    How about the cable noise? When I was experimenting with some PVDF piezo sheets, I found that the cable between sensor and jack is very sensitive, too.
  13. Yes, any movement of the cable is transmitted to the piezo but this is minimised if you use very thin light cable.
  14. Sorry this isn't bass-related, but thought I'd pass on the response from a friend who tried one of these piezos on his daughter's violin:
    "We have tried it out so here's a first impression. I had a squizze in an f/hole and found the sound post was on the treble side of the body and so I placed the piezo under the treble side foot of the Bridge as a shortcut*to the sweetspot. I considered using double sided tape with it placed between the bridge feet. I *will try that when I find it - kids x 3 remember*:)*
    I*plugged her into my*Eden 550/410*and found the output seemed quite low, I had the Gain flat out and the Master around 3 o'clock to get about the volume I would normaly get at a*Gain*at 12 o'clock and Master at 8.30/9.00*All tone controls were flat with no Enhance.
    The sound quality was great. The violin is a typical school type,*not fantastic and a bit thin sounding -*amped up it sounded richer and fuller - a touch mellow and much more resonant.*A sound I liked a lot :) and very usable.
    The next thing I'll probably try will be my son's Korg AX 1G*Effects*Processor as a pre amp to boost the signal - the only option at hand right away."
  15. mje


    Aug 1, 2002
    Southeast Michigan
    Finally built one- my pal Ric had some copper shielding tape- and it only took a few minutes:


    To protect the transducer while I soldered it, I held the pins of the transducer in a pair of needlenose pliers as a heatsink. I tinned the pins and the cable, and then clamped them together and a touch of the iron joined everything securely. I put a single wrap of electrical tape around it and placed it under one foot of my DB.

    Output seems very low, compared to either a K&K wedged into the bridge or a glued on Fishman, but I have some more tests to do, and I want to try building a preamp right on to the transducer pins.
  16. mje


    Aug 1, 2002
    Southeast Michigan
    After playing with the first pickup, I decided to try putting a source follower right on the piezo element leads:


    Granted, this is not how I'd package it in the final version! That would be much smaller, the coupling capacitor would go in the battery box, and I'd use finer wires. But this was enough to test the effects of putitng the preamp on the element instead of the other end of a foot or more of coax.

    It does make a tremendous difference. You get much less signal loss, better frequency response, and no noise friom flexing leads. You don't need to use shielded wire, either, though you still need to shield the element.

    I still don't get great output from placing the element right under the bridge foot, though; these elements seem to work best when flexed. I suspect adding the cork layer (which I haven't done yet) allows the element to flex. I also suspect that gluing the element to a stiff substrate might help.

    Next step is to make some fully shielded units with potted electronics and the preamp right on the pins, but with the coupling cap in the battery box, and then experiment with various substrates.
  17. Does anyone know if these piezo film elements are available in the uk?

    I've been hunting for a while, but haven't found any stockists.

    I've been making pick-ups for a while using the piezo disc elements one can buy at maplin (uk version of radio shack) but this flexible style piezo seems great.
  18. Aleph5


    Feb 24, 2004
    Contacts are listed by the mfr MSI here and some MSI parts may be available where you are via Digi-Key UK.
  19. mje


    Aug 1, 2002
    Southeast Michigan
    I've been dong more research and learned the that these film piezo transducers are much less sensitive in compression than the ceramic transducers used by K&K and others, so you can't just sandwhich them under a bridge foot.The trick is to mount them so that they're stretched by the vibrations from the bridge or top, and that's why the cork layer under the transducer is a critical part of ToneRanger's design. I'm looking for some other complient materials that might work. I'm also looking at gluing the film to a stiffer backing, and mounting it so it's bent by vrabration- which will also stretch the film.

    Stay tuned ;-)
  20. Nice one! Is that fdeck's preamp circuit or something different? Keep us posted on progress with potted electronics - my next solid-body EUB experiment will be with pickups under recessed bridge posts so they connect directly inside the body cavity.

    Another option I'm keen to try (becuse these piezos are so cheap) is to mount 4 of them in bridge slots directly under the strings.