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Wow... The cheapass Radio shack pickup really works!

Discussion in 'Amps, Mics & Pickups [DB]' started by Eilif, Oct 18, 2005.

  1. Eilif

    Eilif Supporting Member

    Oct 1, 2001
    I read the extra long Piezo pickup thread in the BG forums. Lots of good info here:


    I went out and spent the 4 bucks to get a piezo buzzer and input jack from Radio shack. I wired it up, sliced a piece of cork from a wine bottle (to cushion the side with the wires and piezo element) and slid it into the wing of my bridge with the non piezo side against the wood of the bridge facing away from the body of the instrument.

    Lo and behold, going through my K&K 97 preamp it actually sounds good. In fact it sounds good enough that I am considering getting a small mixer or a mixer preamp to be able to use both my k&K Double Big Twin and my Radio Shack pickup.

    The sound isn't quite as defined defined in the high end as the Double Big Twin, but it also doesn't seem to pick up quite as much string noise, which for my use is the biggest drawback to the Double big Twin.

    Keep in mind that this is all on an Englehardt EC-1, so I am not sure if it would preform as well on a bass with a more complex sound.

    I am going to pick up the parts today and try and make a more heavy duty version, and possibly make a version that I can mount under the foot of my bridge.

    One question, does anybody know what kind of pot I should use for a passive volume control (before amplification or preamplification) for piezo pickups.?
  2. I believe you want a logarithmic pot, not a linear one.
  3. Trevorus


    Oct 18, 2002
    Urbana, IL

    If you do end up using a passive setup, use a REALLY high impedance pot. You may look around for a very small buffer pre. I am sure there is some small design that could use a watch battery or something.

    Here's a good small design. I am sure you could also modify the battery input to use one of those tiny 12volt cells, too.

  4. I made a few Radio Shack pickups but found them fairly fragile, and the sound a bit metallic. I've had much better success with the MSI $2 piezo films from here:

    I've also found that the performance is MUCH better when these pickups are under the foot of the bridge. A thin shim of cork or gasket material under it will help make relaible contact.

    A 1Meg log pot works OK for volume although I'd recommend a buffer preamp. With the pickup under the bridge I didn't need a preamp to boost the gain - it was already hotter than my active BG.

    One problem I had with the piezos was getting rid of hum, but I finally solved it with a roll of 3M copper foil with conductive adhesive, which I used to competely encapsulate the pickup & wiring. They're now dead silent, even at high gain.
  5. Eilif

    Eilif Supporting Member

    Oct 1, 2001
    Thanks for the input. That's a Great idea. Also, where do you get the 3m copper foil?
  6. Seems as though what you've done here is made yourself a Realist. I wonder how it compares in sound.
  7. Damon Rondeau

    Damon Rondeau Journeyman Clam Artist Supporting Member

    Nov 19, 2002
    Winnipeg, baby
    I'm not sure it matters -- you can go expensive hydroponic bud but keep in mind Pops made do with real cheap Mexican his whole life.

  8. That stuff is a lot stronger than it used to be.

    I heard.
  9. I thought I'd throw in a word or two about my recent piezo experiments.

    I posted during the experiments with a wiring problem I had, but got no replies on it.

    First, I bought piezo buzzers from Radio Shack.

    I mounted these under the bridge of one of my XZ-25's. I ran the wires out to the control cavity and soldered them onto on of the pots. No go.

    To test it, I wired them directly to a jack and tried that. Nothing but buzz and thumping sounds if I hit the bridge top with my hand.

    So that didn't work, basically. I got two of the piezo films from Experimental and did the same thing. Same results- no output, but thumps if I hit the bridge.

    I contacted both Experimental, and EMG to see what they had to say. Rick Hunt at EMG has answered many electronics questions for me the past few years.

    Rick said: "Sounds to me like you're trying to use a piezo transducer for an application that it wasn't designed for. Traditionally, piezo transducers are used under saddles in acoustic instruments; a metal bridge tends to absorb sound, rather than reproduce it acoustically. While there are metal bridges that have piezo elements, there's a separate element for each saddle, as opposed to a single film for the entire length.
    As for end users using a BTC Control with a piezo, there's quite a few who do so, but the output of the piezo has to be buffered first. Most folks use our PB-1 or PB-2. They also use a saddle/wooden bridge configuration."

    Basically, Bart Hopkin, Rick Hunt and I decided that you can't put a piezo under an electric bass bridge, like you can an acoustic bass. There's too much mass and the piezo is not getting the proper vibrations to sense correctly.

  10. seamonkey


    Aug 6, 2004
    Some ideas if you want to play with piezo's.

    If you're handy with a soldering iron here's a source for piezo elements.

    If you're not, drum triggers are usually just piezo's
    I currently use one for a neck pickup.

    A cheap but good preamp is the Behringer ADI21
    which can be found for < $30 USD.

    An idea to play with the mounting is epoxy the piezo to a strong magnet.

    Round up two kinds of mouse pads. One with a slick surface, and one with a cloth surface. Cut pieces the size of the magnets. Glue the cloth circle to the pizo/magnet, glue the slick circle to another magnet. You can slide the slick one in the f-hole and slide the other on the front of the bass. Then try different locations on the top of the bass. You can use a wire coat hanger to lift the inside magnet around bracing if needed. The magnet is strong enough to work on the bridge also.
  11. I'm pretty sure these $2.00 MSI piezo films are exactly what Realist and several other pickup manufacturers use. I haven't tried a Realist, but this thing is better than other commercial pickups I've tried. The sound is loud and full. I just roll of a few highs and have a great sound out of my EUB. My pickups don't look quite as tidy as the Realist, but at about $4 total cost (piezo, lead, copper foil, jack) and 10 minutes work, you can be sure I'm going to have lots of these to experiment with.

    Eilif wrote: " Also, where do you get the 3m copper foil?"

    That was quite a saga, finding an Australian retailer who didn't want to charge $250 a roll (the first price I was quoted)! Eventually I shamed the wholesaler into letting me have a roll of the 1" tape for about $40, but I'm sure in the US you can find it a lot cheaper. The product I'm using is "3MT 1181 EMI Copper Foil Shielding Tape" - highly recommended for any shielding application.
  12. jstiel

    jstiel Jim Stiel

    Jun 5, 2004
    Lake Orion, MI
    $38 here http://www.hmcelectronics.com/cgi-bin/scripts/product/5315-0126
  13. One more thing I remembered - early in my experimenting I found that you need to use very thin, high quality cable on the piezos. Thicker cable is so stiff that if affects the sound.
    I sourced some nice Mogami cable, the sort they use on lapel mics, from a local pro-audio repairer.