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Piezo pickups?

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9/14/2005 12:45 PM

Piezo pickups?

I've been thinking of making a truly basic guitar with minimal controls and gizmos. I am drueling over some warmoth kits. The simplest I can think of is a guitar with piezo pickups at the bridge, and no more. No pickups on the body at all, and no volume or tone controls. I think this could look pretty cool, but I have never used a piezo pickup and wonder if it just ends up sounding like crap. I know I'd be severely limited in sounds, but with effects and various amp settings it may still be fun. Any thoughts?

9/14/2005 2:27 PM
Earl	I think you'll be happier with active on-board EQ or at least an EQ pedal with that piezo.

9/15/2005 9:10 AM

Every guitar body has resonances, and those resonances depend on where a contact mic is situated. Unless you are able to do a great deal of experimentation in advance (to find which resonances suit your tonal goals), I think it would be unlikely that you would be happy with the tone in the absence of any sort of EQ-ing. The other aspect is that, as a mechanical system/transducer, the possibilities for wolf-tones are huge once you amplify beyond a certain level. As such, some sort of quasi-parametric EQ control becomes essential for taming the amplified instrument.

That doesn't mean the on-board stuff has to be huge or even complicated. For instance, if you knew where the resonances were after you installed the pickup, it could be a simple matter to identify what frequency band needed some attention for feedback or voicing control. That could be translated into some sort of fixed band-reject filter, with a fine-tune trimpot that you could set and forget. That might still permit you to live with only a volume control on the body, and a fairly "clean" guitar surface.

Another thing to consider is that, as mechanical transducers, piezo discs come in a wide variety of sizes, each with somewhat different resonances. You might consider buying an assortment of disc sizes, and situating a couple of them at different regions in the guitar, then mixing them down via trimpots on the pre-amp PCB for a more balanced tone.

9/18/2005 11:12 AM

I've got Christian piezos in Shaller tune-o-matic bridges on my Les Paul and electric 12 string and Fishman power bridges in my 68 Tele and a modded Westone (that one is a tremelo bridge.)

The Fishman on the Tele can nail acoustic tones. The output is too high so I had to pad it down with a large resistor and parallel cap.

The key to convincing acoustic tone with this guitar is the use of acoustic guage strings (10-13-17-30-41-58 on the Tele), the right amp (I use a few different small bass amps with concentric tweeters added) and the right EQ (some bass and treble boost and the RIGHT mid cut.)

I've got lighter gauge strings on it at the moment, 9-46, but it still stood up well tonally compared to several acoustics with piezo bridges through acoustic amps at the store I work at.

On my other guitars, I don't run the piezos separately, but use them to add some high end sheen to their tones.

I've got the Boss acoustic simulator, and while it has it's place, it isn't the same. I've found that piezos DON'T work with this pedal or with an amp with a tweeter in it. It is meant to be used with stock magnetic pickups into a standard guitar amp. Used this way is the way to go. With piezos or tweeters it is too shrill and strident.

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