So I'm tooling around with the idea of putting a bunch of cheap Piezos in guitars, specifically with the idea of using mic preamps to amplify the signal. I am absolutely aware that other amp\preamp solutions are much much better. This is for funsies\be different.
As I understand it, these "pickups" have an output that is slightly higher than a mic, but vastly different impedances as I understand it. Now I don't know the difference between "input and output" impedance or how any of that works which is why I'm reaching out for help.
There are "DI"s available for this, but from what I can tell, these are designed to take a signal that is being amplified from the source pickup, put through a preamp, and then attenuated back down to mic level. What I am looking to do is actually just go straight down to mic level and match the impedance. Basically I want a Neve or API to act as the preamp that comes immediately after the pedal. From what I gather, it might be possible to do this with just a couple chosen components and a cable.
Anyways, I'm having trouble getting information on this and understanding it, even though I'm fairly well versed in gain staging otherwise. Information of getting the pickup to designed amps to take it up to instrument level are abundant, but I have a different use case.
As I understand it, these "pickups" have an output that is slightly higher than a mic, but vastly different impedances as I understand it. Now I don't know the difference between "input and output" impedance or how any of that works which is why I'm reaching out for help.
There are "DI"s available for this, but from what I can tell, these are designed to take a signal that is being amplified from the source pickup, put through a preamp, and then attenuated back down to mic level. What I am looking to do is actually just go straight down to mic level and match the impedance. Basically I want a Neve or API to act as the preamp that comes immediately after the pedal. From what I gather, it might be possible to do this with just a couple chosen components and a cable.
Anyways, I'm having trouble getting information on this and understanding it, even though I'm fairly well versed in gain staging otherwise. Information of getting the pickup to designed amps to take it up to instrument level are abundant, but I have a different use case.
I've found to get the piezo to work at all, you'll need a high value resistor across it. Values maybe 10K - 1M. That's for an instrument input, like on a guitar amp. You can get impedance matching transformers, that will take a HiZ "instrument" input and turn that down to a LowZ balanced microphone signal - that 3 pin cable. I got a little pile of them I bought off ebay, all the way from China.
When you say "a bunch"; I've seen three piezo elements to a 1/4" Tip Sleeve jack as product. The price for the name brand can be pretty steep for this arrangement, but the off-brand ones are cheap enough that there's no way they would have an amp-buffer running off a 9V battery for that price. Those seems to have some kind of backing molded onto the element; in one I purchased, all it is - is hot melt glue in black color.
I sawed the back off of one nylon acoustic - yes, completely removed it - so I could easily experiment with placement of pickups upon the inside surface. I can imagine having several in various places on the back side of the soundboard, with a rotary selector switch, for different sounds...
The idea has been around for 30+ years. What people seem to be doing these days is combining sounds from different pickup elements; one under saddle as is typical to get the strings, one on the top wood somewhere to get that sound and an electret mic somewhere inside / around the sound hole to get the air. Then you mix up some combo of that to try and get it to sound like an acoustic guitar. Some even have the mic part built into the preamp controls, that mount on the guitar's upper side.
Remember this, the piezo element has to bend to make a signal, putting it flat on a flat surface it isnt going to bend much. That's what all the round jobs they sell do. I think I even tried clamping the disc edge into a little wood stud I could glue into place, letting the element "flap"; even put a weight on the far end. Nothing I've tried even remotely sounded OK, using those round jobs or the film elements.
When you say "a bunch"; I've seen three piezo elements to a 1/4" Tip Sleeve jack as product. The price for the name brand can be pretty steep for this arrangement, but the off-brand ones are cheap enough that there's no way they would have an amp-buffer running off a 9V battery for that price. Those seems to have some kind of backing molded onto the element; in one I purchased, all it is - is hot melt glue in black color.
I sawed the back off of one nylon acoustic - yes, completely removed it - so I could easily experiment with placement of pickups upon the inside surface. I can imagine having several in various places on the back side of the soundboard, with a rotary selector switch, for different sounds...
The idea has been around for 30+ years. What people seem to be doing these days is combining sounds from different pickup elements; one under saddle as is typical to get the strings, one on the top wood somewhere to get that sound and an electret mic somewhere inside / around the sound hole to get the air. Then you mix up some combo of that to try and get it to sound like an acoustic guitar. Some even have the mic part built into the preamp controls, that mount on the guitar's upper side.
Remember this, the piezo element has to bend to make a signal, putting it flat on a flat surface it isnt going to bend much. That's what all the round jobs they sell do. I think I even tried clamping the disc edge into a little wood stud I could glue into place, letting the element "flap"; even put a weight on the far end. Nothing I've tried even remotely sounded OK, using those round jobs or the film elements.