The ESP Guitar Company

It's another type of pickup that senses vibration or more like pressure from the saddles...

Mostly used for acoustic tones, but in the case of a Variax, it takes the pure string signal and then you can process the tone to sound like whatever model of guitar you want...

It incorporates a piezoelectric crystal, which is a crystal that generates a proportional voltage when it is subject to pressure (such as sound waves), translating vibration into an electrical signal :)

If you had a guitar with only piezos, with no magnetic field pulling the strings down, etc, you would probably see an increase in sustain. I guess that depends on how sensitive piezos are relative to magnetic pickups, so I'm not sure if it's true in practice, but theoretically, it's a viable thought :)

It's been intriguing me, actually...

Yeah, I've seen guitars with a seperate output for the piezo. Pretty sure Paul Reed Smith has a model like that :)

Urgh, Piezo lust is beginning... :S

you guys need to play some parkers hahah they have a model that has only peizo pups on it actually they have two :)