Piezo discs: bridge or sound board?

I see some people embed piezo discs in the tail end of the neck under the bridge. Other folks attach them to the vibrating sound board. The bridge makes sense to me on one side, but it’s usually then butted right against the neck and not free to vibrate which doesn’t make sense.

I’m planning to build a few simple guitars with piezos soon so I’d appreciate your explanations and thoughts on where you locate them and why.

Thanks,
Scotty

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Permalink Reply by BrianQ. on October 14, 2020 at 7:58am

Here’s some reading on the subject, there’s a few other articles on the how & why of piezo’s there too?

https://www.cigarboxguitar.com/knowledge-base/using-piezos-in-cigar...

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Permalink Reply by Taffy Evans on October 14, 2020 at 12:06pm

Hi, there are many builders that have experimented with piezo placement and each will have a position/location that worked best for them, in their instrument. Some use a piezo to improve the volume of their acoustic instrument, and others will also add a preamp to the system to tame and control the output.
Some use the piezo just as a pickup and not worrying about acoustic properties and play it through an overdriven amp. A cheap way to get an electric guitar.
Magnetic pickups convert the plucked moving string into sound. The piezo disc pickup/transducer converts the moving/vibrating top [or whatever its attached to] into sound. As a rule, the more intense the vibration the louder the output.
So really its up to your ears, I think, put it where it works best at reproducing the acoustic tones of your instrument.
The piezo transducers I use in my full-size guitars are of a professional quality, so the manufacturer has worked out where they perform best, directly under the bridge. There are three discs in all, and a kit and 23 pages of instructions are supplied to ensure it is done correctly.
However, in a CBG the range in tone is not as full, and each box is different, so experiment.
Taff

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Permalink Reply by Taffy Evans on October 14, 2020 at 12:14pm

Hi again Ducati, I should have also said that your assumption is correct, in that having the neck connected/touching the top will limit the output of the tops vibrations. But it depends on how well the top vibrated in the first place.

Taff