He pronounces Piezo right but μF wrong. It's Micro Farads, not Uicro Farads, you dolt! Nhyuk *adjusts glasses*
Damn straight. Those fuckers are the Devil's smegma.
Make Magazine is awesome. I don't care if that makes me a hipster, it's true.
Would you like to see my fedora? It's been custom fitted with photosensitive plates that deploy a translucent sun-shade when they detect a significant quantity of natural light.
Make is great, even though I've never made anything from it for some reason.
I don't like how it basically exists to sell you kits, but it's a fun read and I made a robot mouse thanks to it, so I'm not complaining!
I was about to make a 'pickup' artist joke, but I see you beat me to the punch. Well played, sir.
(point to circuit schematic)
This is complete overkill because
A) you don't need onboard electronics for a piezo pickup (you don't need to worry about the impedence mismatch when you're using it wth an amp, it's not that bad; if you're running it to a mixer a good DI will give better results than what he built anyway).
B) no matter what you do its still going to be a piezo pickup. I've used some absolutely worl class piezo pickupsand they still sound like that. It's an ugly sound for a guitar.
Best way to do it is to take the piezo disc, dunk it in some of that rubber stuff they use to coat the handles on pliers (optional, but makes it stronger and helps with that brittle piezo attack a bit) and solder a connector of your choice to the other end. DONE for under assuming you use a decent connector.
The best sound I've gotten from an amplified acoustic instrument was by actually mounting a PZM (with the stock plate removed, they're too small and resonant anyhow) to the inside of the back. I did it on a banjo, though doing that on a guitar would be more intrusive and depending on where you stand on the "active vs inactive back" debate in luthiery, you might not want to risk changing the tone of the guitar by adding weight to the back.
Building piezo contact mics for uses other than realistic instrument pickup is a whole other issue, though, they're fantastic to have around and in some cases having onboard electronics would be nice I suppose.
The other issue with using it on a guitar is that the entire soundboard becomes the diaphragm of a microphone, so don't expect to use it at anything approaching concert levels without massive feedback issues. A better use is to p it on a stand near your drummer's kit, tune it to the key of the song you're recording and blend it in as a weird, harmonic reverb.
So why use a preamp?
1) You can drive a low impedance cable to your amplifier.
2) You can bias the piezo crystal.
Accomplish #2 by tying the input to the transistor to the center of a voltage divider from 9V to ground. This could be a 1M variable resistor, for example.
Finding the right bias voltage will improve the sound, but as you say there are limits to what can be done with this. Why this douchenozzle doesn't include that bit of circuit is beyond my Ken.
Bwahahaha. My plan to post this and have poetv's super-nerds explain and expand upon it has come to fruition!
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