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Problem with EQ-7545R Pre-amp...

Posted by Jim Saraceno on May 7, 2017 at 12:26pm in Building Secrets, Tips, Advice, Discussion

I am trying to make a pre-amp/equalizer for my guitars with piezo pickups. I ordered an EQ-7545R pre-amp, I did the Shane Speal hack of cutting the rod piezo off and soldering on a 1/4" jack. When I hooked it up I got nothing. No sound, nada.

Anyone have any ideas?

My first mistake was not ordering it from C.B. Gitty so by cutting the piezo wire I can't really send it back. My second mistake is I should have hooked it up before doing the hack so I would have known if the unit never worked or if I somehow did something to mess it up.

Unless anyone has had a problem with the Gitty unit, I'll just order one from them and try again.

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Replies

  • John Rivers May 11, 2017 at 7:10pm

    Gotta cut the piezo between the humps

    I have handled at least 1,000 piezos and never saw one that had no sound.

    • Jim Saraceno > John Rivers May 12, 2017 at 7:50pm

      Thanks but it is not the piezo that doesn't work it is the pre-amp.

  • John Sawyer May 9, 2017 at 9:02pm

    Post a detailed pic...

    Does the battery check light work?  show us your soldering job, etc...

    I'm pretty famous for wiring things backwards once in a while... My R/C airplane friends call me wrong-way...

    • Jim Saraceno > John Sawyer May 10, 2017 at 10:47pm

      Thanks but I just received a unit from C.B.Gitty and it works just fine. Apparently I did everything right on the first unit but it just doesn't work. I'm sending it back.

  • David L. May 7, 2017 at 4:58pm
    You could try a new 9v battery, make sure all slide buttons are on max and also make sure the small master volume knob is switched to max too.

    Are you using an amp cable with mono plugs? (The shaft of a mono plug connects two negative wires from the battery switching the unit on. A stereo plug doesn't connect the two wires so the unit stays off).
    • Jim Saraceno > David L. May 7, 2017 at 6:03pm

      Thanksabut I tried a new battery and all knobs at max (and mid, and min just in case). I have no stereo jack plugs, they are all mono.

  • JL May 7, 2017 at 3:57pm

    if its the same 1/8 in mini jack on the end of the piezo rod that the gitty unit has, you can test the pre-amp with an aux cord from your music player or smart phone.  if that works, you can buy a 1/8 male end and use that instead of cutting the braided cord

    • Jim Saraceno > JL May 7, 2017 at 4:42pm

      It is not an 1/8" jack, it is a 3/32" jack. (2.5 mm. instead of a 3.5 mm). It'll be interesting to see if the Gitty unit has the 1/8" jack.

  • Jim Saraceno May 7, 2017 at 3:42pm

    It sounds like I have done everything right. I'm not going to mess around with it anymore, I just ordered one from Gitty like I should have from the beginning. I can just put the piezo from the new unit and put it in the bad unit and return it.

  • David McQueen May 7, 2017 at 2:45pm

    1. You can buy rod piezos on a braided wire to replace the one you cut. They are on eBay and they are cheap.

    2. The on off switch in the preamp is the guitar jack going to the amp. Plug it in and the preamp is on.

    3. I just soldered the disk piezo directly to the braided mini jack wire and plugged it into the preamp at the mini jack female plug.

    4. Once you do that, put in a battery and plug the preamp into an amp. Touch the piezo to test the preamp.

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