I'm working on a license plate resonator guitar with two piezo pick-ups. The piezos are super glued to the back side of the plate, either side of the bridge.
This guitar also has a CB Gitty 3 pole, prewired, dual humbucker pick-up installed. I plan to use a 3-way switch to switch between the piezos, the humbucker or both. I'll have a volume knob for each pick-up and a tone knob for the humbucker only.
I would like the volume output from the piezos to be approximately the same as the humbucker volume output. So my question is: should I wire the two piezos in parallel as normal or in series for more voltage?
I can add more piezos in series for more voltage or in series-parallel for more oomph. What has been your experience?
You’ll have to run the piezos through an onboard preamp, series has more output though? FYI, the Fender powerstrat has a similar configuration,good luck
I read somewhere (maybe on this site) that the Piezo has such high impedence that is has trouble impedence matching with most amps. One way to lower this impedence is to put Piezos in parallel. I've tried this and there does seem to be less amp hum without loss of volume. Therefore, I say parallel.
Tom is right. Wiring in series just magnify's an already bad problem with the impedance.
Multiple piezo's should be done in parallel.
The more expensive acoustic preamps have hookups for piezo and magnetic pickups and they add a buffer to the piezo while equaling the impedance mismatch. They can go for several hundred dollars.
I have a git with a humbucker and a piezo wired to separate pots(500k HB & 1meg piezo) and a 3-way switch. It works okay.
Think of it this way. Series doubles the impedance. Parallel divides it in half. Unfortunately you may not get the same output between the pickup and the piezos. Could turn the pickup volume down a bit to make up for the difference. Let your amp work harder to get the over all volume level you need.
After thinking about this alot and reading the generous advice above, I decided to build a simple test jig.
I hot glued four jumbo piezo disks to the inside lid of a cigar box. I put them in a square configuration right in the center of the lid. I took two of the piezos that were diagonally across from each other and wired them in series. Then I took the other two piezos that were also diagonally across from each other and wired them in parallel.
Next I put an output jack and a SPDT switch in the side of the box so that I could swap instantly between series and parallel.
Then I plugged it into an amp and started tapping on the box.
As with most things in life, the sound output was a compromise...
The series setting does give more output volume. Maybe 10 or 15 percent more, but it also picks up more hum from flourescent lamps. The sound in the series setting is also fuller compared to the parallel setting. In the parallel setting some of the lower frequency sound rolls off, but the hum is noticeably less.
Since this is going into a resophonic style guitar, I think I'll go with the parallel wiring in order to get a sharper, more jangly tone.
I'll let you all know how it comes out.
The series wiring could be a good thing to have with low output volume amps as long as you use a lot of box shielding and enough insulators between the piezo's and box. Solid body gits might work better with that type of wiring.
An excellent approach to a common question. Your experiment should be helpful to a lot of folks.
I am just about to put two piezos in my latest build and found your research invaluable. Many thanks.
Now that the build is finished, I have the answer to my own question.
The dual piezos wired in parallel are actually louder than the humbucker! If I run the humbucker at full volume, the piezos have to be set at about 2/3 to 3/4 volume to match.
Ill get picures up ASAP.
By the way they sound great. Thanks for all the advice.