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Thinking of throwing together some pre-made harnesses to sell.

Soldering is no problem, on/off switch equally easy.

But I plan to include a volume pot, so piezo, pot, jack + wiring.

I know 500kohm pots tend to be used in multi-pup guitars, and 250kohm in single pup builds, but that tends to be for traditional variations on mag pups.

Any idea what the ideal resistance would be using a standard 27mm piezo disc?

Just thinking along the lines of not everyone is comfortable with soldering but can handle the woodwork would be happy to throw down a couple of quid for a ready wired harness that just needs fitting.

So any advice for pot resistance with a single piezo, I know there is an electronics and wiring group, but this is barely technical enough to be asked there.

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Replies to This Discussion

Permalink Reply by Kevin Lawton on September 23, 2010 at 3:17am

Yeah, you need to match the Pot to the impedance of the piezo as closely as you can. 2 megohms - is going to be as close as I can guess without measuring the piezo myself. It might come as a 'standard value' 2.2 meg. That'll do fine.
The problem occurs if you are planning on running a piezo into an ordinary guitar amplifier without some kind of pre-amp to buffer it.
The input impedance of the guitar amp will be much lower than the impedance of the piezo and ruin the tone you hear.
A small pre-amp to buffer against this problem is the 'correct' way to go. A pair of matching piezos wired together in series (and in phase of course) can help alleviate the problem greatly.

Permalink Reply by Carl Robson on September 23, 2010 at 3:21am

Interesting. On my second build, I just used one 27mm and it sounds ok, but on my first build I used a 27mm and I think something like a 40mm in series. I was worried it would ruin the sound but it works OK.

My amp is just a little Nevada G10 which isn't really that good, but it was a couple of quid secondhand and just something to make a bit of noise through.

Kevin Lawton said:

Yeah, you need to match the Pot to the impedance of the piezo as closely as you can. 2 megohms - is going to be as close as I can guess without measuring the piezo myself. It might come as a 'standard value' 2.2 meg. That'll do fine.
The problem occurs if you are planning on running a piezo into an ordinary guitar amplifier without some kind of pre-amp to buffer it.
The input impedance of the guitar amp will be much lower than the impedance of the piezo and ruin the tone you hear.
A small pre-amp to buffer against this problem is the 'correct' way to go. A pair of matching piezos wired together in series (and in phase of course) can help alleviate the problem greatly.

Permalink Reply by Naz Nomad on September 23, 2010 at 4:20am

I'm in the process of doing this too ... survival of the neatest, eh? LOL

Permalink Reply by Carl Robson on September 23, 2010 at 4:24am

Yup, guess it is.
Hopefully I can put a few glass slides out and about too since I bought the diamond cutoff wheels too.

Naz Nomad said:

I'm in the process of doing this too ... survival of the neatest, eh? LOL

Permalink Reply by Naz Nomad on September 23, 2010 at 4:30am

You should try selling some wood/bone ones ... oh wait, that's ''punishment by death'' in some places. :-))))

Carl Robson said:

Yup, guess it is.
Hopefully I can put a few glass slides out and about too since I bought the diamond cutoff wheels too.

Naz Nomad said:
I'm in the process of doing this too ... survival of the neatest, eh? LOL

Permalink Reply by Carl Robson on September 23, 2010 at 4:44am

Hah, seems like a popular idea at the moment.

Permalink Reply by James Deeds on October 10, 2010 at 6:45am