If we want to get ANY info that we can extrapolate to our own situation, it's very important that any sound file or report be accompanied by w precise
description of placement and intermediate electronics.
Piezos are very high impedance devices. This means they are weak generators of voltage. Anything, even cables, that is wired in with piezos makes a
complex circuit with them, so that hi-lo-pass filters are created. The frequency response of piezos cannot even be measured, the measuring circuit
completely changes the results. You can unpredictably get excellent sound out of simple piezos if you experiment. If you add a buffer circuit, which
can be a single transistor or a complex preamp with controls, you can strengthen the signal so it becomes less influenced by what you plug it into.
People who claim THEIR piezos have special frequency response are generally selling you a whole expensive assembly. It's not the piezos. The point is
that pickups can generally only be characterized in connection with what you feed them into, and where you place the sensors on what type of
instrument. So please provide detailed and complete information.
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