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Need help-piezo only picks up inner strings.

Posted by Seane Crews on November 21, 2010 at 1:48pm in Building Secrets, Tips, Advice, Discussion
Hey, guys.

I was a member of the old Yahoo group, and just joined this one. I recently built a 4 string, fretted baritone CBG tuned BEAD, low to high. The piezo pickup is imbedded in the bridge plate (a piece of red oak) and insulated with a piece of thin foam. The two inner strings come through great, but the outer two can barely be heard through the amp. I wouldn't think the piezo is defective since it picks up two of the strings, but I'm not sure.

Any ideas? Thanks,

Seane

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Replies

  • MichaelS Country Boy Guitars December 3, 2010 at 8:03pm
    Now thats a good idea, best of both.


    Huntz Meyer said:
    I read this post while building my first six-stringer (customer request). Dual piezos, another first, sounded like a safe bet. They are 20mm Gitty's between the lid and neck, evenly spaced under the strings. I like to button 'em and be done, so I wired in a switch for series-parallel:

    I intended it to be a set it and forget it switch so it is flush with box side under the jack. A pocketknife switches it.

    cbg_101115e.jpg


    At home with my Noisy Cricket, with 100K pulldown resistor on the input, parallel sounded best - smooth and natural. At the guitar store, through a Fishman amp, parallel made the high E string considerably louder that the rest. Flipped to Series and everything evened out and sounded great. It was my first attempt at recoding a video, and the card filled up just as we were getting to the electric, so I don't have a recording of the difference.
    http://www.huntzmeyer.com/gallery.html



    For a stage CBG, a DPDT On-On toggle might allow for different effect, but if you run dual piezos the switch makes life easy.

    Thanks,
    Huntz
  • Huntz Meyer December 3, 2010 at 1:38pm
    I read this post while building my first six-stringer (customer request). Dual piezos, another first, sounded like a safe bet. They are 20mm Gitty's between the lid and neck, evenly spaced under the strings. I like to button 'em and be done, so I wired in a switch for series-parallel:

    I intended it to be a set it and forget it switch so it is flush with box side under the jack. A pocketknife switches it.

    cbg_101115e.jpg


    At home with my Noisy Cricket, with 100K pulldown resistor on the input, parallel sounded best - smooth and natural. At the guitar store, through a Fishman amp, parallel made the high E string considerably louder that the rest. Flipped to Series and everything evened out and sounded great. It was my first attempt at recoding a video, and the card filled up just as we were getting to the electric, so I don't have a recording of the difference.
    http://www.huntzmeyer.com/gallery.html



    For a stage CBG, a DPDT On-On toggle might allow for different effect, but if you run dual piezos the switch makes life easy.

    Thanks,
    Huntz
  • Don Thompson November 26, 2010 at 4:16pm
    Piezo elements are totally different than magnetic transducers in their respective electrical measurements. Hence the irritation on my part when people insist on treating them the same, piezo tone control diagrams that mimic magnetic circuits that are meaningless and useless for example. Just so much bullshit. So much attention is paid to the high impedence with piezos that the other parts of Ohm's law are forgotten. Inductance, resistance and capacitance characteristics and how those numbers relate to one other is very important in the tonality of a transducer. In the instance of series wiring the capacitance which loads your amp is half of one piezo but double the resistance and impedence. For parallel wiring the opposite is true, capacitance is doubled, impedence halved as is resistance. Capacitance is one of the things that affects how a certain transducer will load or in another words, affects the sound coming from an amp. Depending on amp and your cable increasing total capacitance may not sound as good. There is a reason all transducers have their particular sound and with proper measurement it can be determined why. For most of us that instrument to measure by is our ears.
    Ok?





    Seane Crews said:
    I built a new bridge with two piezos as Don suggested, wired in series, and everything worked fine. I glued them into the wood bridge with c/a, used some thin foam the keep them good and snug inside, and sealed it up with another piece of thin wood. I tried both series and parallel, and to me series sounded better. I can also get more volume before feedback than with one piezo.

    I'll try to get some pics up later. Thanks to everyone for the input.
  • MichaelS Country Boy Guitars November 24, 2010 at 5:59pm
    OK, now I may have to do a series wire-up just to compare it with my parallel piezos. How would you describe the sound difference?

    Seane Crews said:
    I built a new bridge with two piezos as Don suggested, wired in series, and everything worked fine. I glued them into the wood bridge with c/a, used some thin foam the keep them good and snug inside, and sealed it up with another piece of thin wood. I tried both series and parallel, and to me series sounded better. I can also get more volume before feedback than with one piezo.

    I'll try to get some pics up later. Thanks to everyone for the input.
  • Seane Crews November 24, 2010 at 2:14pm
    I built a new bridge with two piezos as Don suggested, wired in series, and everything worked fine. I glued them into the wood bridge with c/a, used some thin foam the keep them good and snug inside, and sealed it up with another piece of thin wood. I tried both series and parallel, and to me series sounded better. I can also get more volume before feedback than with one piezo.

    I'll try to get some pics up later. Thanks to everyone for the input.
  • Don Thompson November 23, 2010 at 1:51pm
    I am one that falls firmly in the group of try it both ways. We expect a full report back on your findings.
    Don



    Seane Crews said:
    OK, as Don suggested, I am going to first try using two piezos instead of one. What are the pros and cons of wiring the two in series vs. parallel? Just by looking at the diagrams, I would think that parallel would be hotter, but series would take the edge off a little bit. Then again, all of my prior experience has been with one so it's just a guess.
  • MichaelS Country Boy Guitars November 23, 2010 at 11:43am
    Wire them parallel. Sounds better.

    Seane Crews said:
    OK, as Don suggested, I am going to first try using two piezos instead of one. What are the pros and cons of wiring the two in series vs. parallel? Just by looking at the diagrams, I would think that parallel would be hotter, but series would take the edge off a little bit. Then again, all of my prior experience has been with one so it's just a guess.
  • Seane Crews November 23, 2010 at 10:19am
    OK, as Don suggested, I am going to first try using two piezos instead of one. What are the pros and cons of wiring the two in series vs. parallel? Just by looking at the diagrams, I would think that parallel would be hotter, but series would take the edge off a little bit. Then again, all of my prior experience has been with one so it's just a guess.
  • Robert John Spotti November 23, 2010 at 4:52am
    Seane,When I built my first two guitars they were identical except for the amount of strings one being 3 the other a 4 on the second I put silicone around the piezo the response was vastly different.So much so I took it apart and removed the silicone.It made a huge difference.I finally had two similar sounding guitars.I'm speaking from experience only it worked for me.Both piezo were in exact placement,neck,box,scale length ,tuners and string brand were identical the only variable was the silicone once it was removed the problem was solved.Good Luck!
  • Don Thompson November 22, 2010 at 6:21pm
    http://www.artecsound.com/acou/piezo.htm
    As I stated before your saddle is not in contact with the piezo, the vibrations on the outside strings are being damped by wood . The simple drawing shows what I mean, the saddle contacts the piezo therfore the string vibrations are equally transmitted to the piezo. Yours doesn't. No amount of changing glues will change the way your bridge behaves. A single piezo would certainly work on your soundboard but in your situation I would go with two and be done with it.
    Don
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