I wired up the pot, jack and piezo today, plugged them in to a guitar amp, held them under the string of another guitar and plucked, it worked like a charm except for one thing. Apparently I wired the pot backwards or something. When you turn it toward off, it gets louder and then when you click it off, it doesn't shut off. Turning the other way makes it quieter. I wired it per directions I found in the Radio Shack reviews which also matched pictures I found of other people's pots.
Blue wire on left #3 goes to red wire on piezo. Blue wire in center #2 goes to positive on jack.
Brown wire goes to negative on jack and black on piezo.
Do I just need to switch the blue wires?
I know my soldering is messy, I have a crappy 35 year old, 30W iron.
Here is the pot I used:
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I'm about ready to wire up two pickups and this helps a whole lot.
Thanks wormil!
Did you ever get it working? If so how does it sound?
I meant to update this and hadn't gotten around to it yet... I left it alone and when I did a test installed the circuit worked correctly, not sure why it seemed to be backwards during the initial test but turns out it was wired correctly. When you turn it "off", no sound is getting to the amp. Not sure if that is because the actual switch is functioning or if the pot is just going to zero, I suspect the latter; either way it works. I tested the circuits with a multimeter and am within 400 ohms of the pot rating, that's only a 0.04 variance so I guess my soldering was good.
If I'm measuring changes I use linear taper potentiometers, listening for changes an audio taper.
Liner taper potentiometers make resistance changes in straight line but the perceived effect is in steps.
Audio taper makes the changes in a way that is more suited to the human ear and the transition sounds more smooth and natural.
StewMac has a real good article here
John
Thanks John, I should have studied up before soldering but I was so excited about the other aspects of building. Someone told me that if you solder a taper pot backwards, as I have done, it will change the way it was meant to behave.
Do you really need an on/off pot?
No, I suppose not. It was just there and seemed a shame not to use it.
I was just curious if this is what is causing the problem, probably not but I have never used a pot with an on/off and am wondering if it's the root of the problem?
Update. I learned a lot about potentiometers today. First, the diagrams posted all use a 250k or 500k linear pots but I bought a 10k taper pot switch. Taper pots are designed for audio and work a little differently. They are supposed to be better but apparently modern taper pots are so cheaply made that better has turned into 'just different'. According to what I've read, the lower the resistance the more treble roll-off (loss) you may have. 250k (less treble) pots are recommended for single coil pick ups while 500k (more treble) are recommended for humbuckers. I'm not sure how my 10k will really affect the sound, guess I'll find out once I get tuners/strings installed.
Well in a sense, yeah. I used an audio pot with an spst (on/off) switch which apparently most people don't use and I wasn't familiar with how to wire it. It does control volume as wired, it just isn't wired correctly for the type of switch it is. I may just leave it alone as I don't really need an on/off.
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