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Piezo in P-Bass wiring question

Discussion in 'Pickups & Electronics [BG]' started by skrabadonk, Oct 23, 2004.

  1. I wanted to try the mod with adding a cheap piezo that was discussed in another post, problem is I can't get it to work properly.

    I've installed the piezo in my P-bass and I want to control it with a separate volume pot and also be able to control it with the tone pot. So I'll have two volume pots and one tone. I've resoldered it about 6 different ways now and I can't get it right. Ant ideas?

    Would it be easier to just wire the piezo with the volume pot and only use the tone for the P-bass PUP?

  2. Jazz Ad

    Jazz Ad Mi la ré sol Supporting Member

    There is a huge difference in impedance between magnetic and piezo pickups. You're gonna need a preamp of some kind to properly blend them.
  3. PasdaBeer


    Nov 2, 2002
    Santa Rosa California
    SandStorm Designs
    your gonna need to buffer it to work right at all.
  4. RyanHelms


    Sep 20, 2003
    Cleveland, OH
    Yep, the piezo almost has to have an impedance buffer/preamp. Although, you can go completely guerilla and solder the piezo directly to the output jack with it's own on/off switch or volume pot. That was the first thing I tried and lo and behold, you do get some piezo signal through, enough to hear a difference. *But* - in order to to have any appreciable signal whatsoever or any tone control to speak of, you unfortunately have to active :/
  5. Thanks for the input. I was kind of going for the lo-fi approach and try to get by without any active/buffer things. I can get a sound out of the piezo and and out of the original pup. However, I can't seem to get the separate signals no matter how i wire them.

    Basically, the piezo is not the problem. The problem seems to be my inability to wire two the two pickups in paralell. Hope this clarifies things a bit.

    BTW, the point of installing the piezo is mainly because I want to use the bass as a drum from time to time.

    Any advice/help/comments are appreciated. :eyebrow:
  6. RyanHelms


    Sep 20, 2003
    Cleveland, OH
    "However, I can't seem to get the separate signals no matter how i wire them."

    Without buffering and pre-amping the piezo, you really won't either.

    "Basically, the piezo is not the problem"

    The piezo *is* the problem, or rather it's output impedance. You can wire them together all day long and you'll still really only get the magnetic pickup signal, with a hint of piezo.

    In order to use the bass body as a drum, you would absolutely need to buffer and add quite the amount of gain...sorry 'cause I know that's not what you wanted to hear, er uh, read :/

    edit: On the positive side of things, it's the piezo's fault, not yours.
  7. Thanks for the help. I guess I'll have to come up with a different aproach.
  8. I know this is an old thread but, What if they were blended with a blend knob[making the magnetic pickups less "loud"] and the amp was then used as a "pre-amp" by simply turning it up?

    Would this work?
  9. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    Hi Fatboy, no offense :) but you keep asking the same question hoping someone will tell you what you want to hear. Adding a blend pot will not change the impedance of either pickup. Impedance and loudness are not the same thing.
  10. No offense taken. I hope it's more obvious that I really don't understand much and I would really like to learn. I have searched through about 20 pages of threads with the word "piezo" in it and still am not getting it. One person will say that a piezo without a buffer/preamp will work the other says no it won't . Then I research and find basses made that have no active electronics with both mags and a piezo thus adding to my confusion. If the impedance is high what does that do when mixed with a mag pup? Don't you just get a mag pup sound with a hint of piezo? If one were to turn down the mags or blend them like a Jazz does wouldn't that work to create a "balanced / mixed" signal of the two? Then increase the volume to bring it to where you want it?

    Still learning,
  11. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    Hi Fatboy, I know there is one luthier who's figured out a way to passively blend a magnetic and piezo signal (I think I put the link in your other thread). So yes, I think it can be done. I have personally tried it and didn't have luck, so I'm just sharing my own personal experience, as well as the advice of people like Rick Turner whose opinion I trust. I'm not saying your experience isn't worth trying :)

    An analogy is speaker cabinets. You know how speaker cabs come in 4 ohms or 8 ohms, right? You can combine a 4 ohm with an 8 ohm cab, but one would get more power than the other. Turning the volume up or down does not turn a 4 ohm cabinet into an 8 ohm cabinet; it's a measure of resistance to current, in other words, the amp pushes and the speaker pushes back a little. Well, mixing a magnetic and a piezo is like trying to match a 4 ohm cab with a 4,000 ohm cab... does that help you to visualize it better? It's not a case of one being twice the impedance of the other, it's entire orders of magnitude.

    ps sorry if I sounded negative, it's been a long day, and your question is perfectly reasonable :)