Odd Piezo problem

[Jimbob Jones]

I read the stickies, FAQ and did a search, but couldn't find the answer to my question.

I recently felt like it would be a good idea to add a piezo pickup to my precision copy, to widen it's tonal pallet. The circuit was going to be similar to a telecaster, with a 3 position switch, one volume and one tone control.

I bought a Piezo transducer from Maplins (UK version of Radio Shack) it looked like this:


When it was wired into my circuit, I plugged the circuit into my amp, tapped the piezo with a screwdriver, and a satisfying click was heard, telling me it was working. So I put my bass together, with the piezo under the bridge, only to find that the piezo had stopped working.

So I took the bridge off, checked the piezo out, did the screwdriver test, and it was fine, so I put my bass back together again, and the piezo still wasnt working.

I know as a rule piezos are normally associated with active electronics, but i had a clean clear signal when it wasn't under the bridge.

Is the pressure the bridge is exerting stopping the piezo from working? is there anything i can do to fix this problem?

Thanks in advance for your help!

[hartke20g]

when you tap the piezo with the screwdriver, tap the mag pups too. it's hard to hear a piezo without a buffer when it's combined with mag pups. it's possible that the normal pups are still producing sound.

edit: i just remembered the outcome of doing this to my jazz a year ago. i had the piezo under the bridge too, and i got a weak output. i think that the amount of pressure between the body and bridge is so great that the vibrations are nearly unnoticeable at that one point. since the pressure doesn't let anything move, the piezo won't pick up vibrations that aren't there. i ended up putting the piezo underneath the neck pup, and then completely removing the piezo a week later (a LOT of feedback with distortion at high volumes).

[Jimbob Jones]

well, I have a pickup selector switch, so i can solo the piezo, and there was no volume at all.

Thanks for the reply, I'm a little confused though, because I've heard of these things being put under one leg of a double bass bridge, which applies lots of pressure?