Figured I'd share this while I was here today - something born of desperation one Saturday night building a CBG for a customer.
Most of my guitars use a combination of a magnetic pickup and a piezo. I love the warm, fuzy sound the piezo adds. I feed them to the output jack through a blend/balance pot so you can dial in just the right mixture of mag and piezo - or dial out the piezo all together if you're in a wild environment and the piezo is generating too much feedback.
But, one evening in the shop, I'm putting the finishing touches on what I feel will be a really kick ass CBG and I realize I am out of blend/balance pots. A few dollars went into the swear jar. But after a few hours of moping, cursing (and damn - even cleaning up!), a light bulb went off for me. I remember vaguely from an electronics class years ago that a piezo is a capacitor of sorts. In fact, a capacitor with a pretty high impedance, just like you'd use in, say, a tone circuit...
That customer guitar suddenly took a back seat to some fun experimenting with some test guitars in the shop. Here is what I did: I wired a typical tone circuit like Ted outlines here. But, instead of a standard capacitor I used a piezo with long leads so I could glue it to the inside of the lid, just as if I was using it as a pickup.
In fact, it worked pretty darn good. The tone pot at zero was sending pure, clean mag pickup to the output jack. Then, as I dialed it up it began bleeding off high-end just as a tone pot should. But there was more - the low end got a little warmer, a little fuzzier - the piezo was feeding back into the circuit some of that unique piezo sound. It was sort of an actively passive tone circuit.
I did some googling and it became obvious I didn't invent this. Well, I came up with it on my own, so i sort of invented it, but many others had done the same or similar long before me.
Anyway - give it a try! If you have a mag pickup you just can't get to sound the way you want, try the piezo in the tone circuit trick. I've found it really gives new life to cheap, tinny sounding single coils.
My brain is about to explode! Dang Bob, I have to fool around with this. Thanks for the creative tickle...
(wonder what it would add to a circuit with inexpensive, awesome sounding Crocker DownUnder single coils?)
There is much experimenting to be done! Multiple piezos? in series or parallel? Placement?
Also, I totally need some Crocker p'ups. Gonna pull the trigger on that very soon.
bob,just tried piezo as cap in tone cicuit,definately something to play with,on board gain is cool