Hello everybody! Been working on my first build for about a week now and have used this site many times for advice. I haven't joined a forum site in forever but I felt like this was one I needed to be a part of. I've absolutely fallen in love with guitar building. I plan on building many CBG's and eventually would like to build a full size guitar. Anyways down to business.
I decided that I was go big or go home on this first build. 4-string, fretted, volume and tone. Everything has gone nicely so far except for one thing....I was getting that annoying buzzing noise when I turned up the volume. So much that I could barely hear me knocking on the box at max vol.
I was using a piezo transducer from RadioShack mounted to soundboard via hot glue. One 500k WD pot for volume and one 250 for tone from a local music store. .022uf cap and 1/4" jack from the shack. 22 awg (I'm assuming "unshielded") throughout. Everything grounded to the volume pot. No bridge no strings no tuners no frets. I am waiting on frets to arrive so that's why I am also holding off on the rest.
I wound up mostly fixing the problem by robbing the electronics out of an old starcaster and soldering wires together here and there. I did no new soldering to the back of the pots. However, there is still a very faint buzz. Tolerable but I still hear it. The odd thing is that it goes away when I turn the volume to max. This finally brings me to my questions about buzzing and grounding and soldering.
Was it buzzing because I didn't have a bridge/strings to ground it to giving the signal more area to displace or whatever? Also do I need to be using a shielded wire? I noticed when I took the guts from the other guitar is was that shielded type wire with the braided ground around it. Or maybe my soldering joints were not so great? I burned up a few from re soldering so much trying to get rid of the sound. I checked for continuity everywhere, all good. Even to the end of my guitar cable. All my other guitars work fine. Tried it in other rooms so I don't think it EMI. The other thing I suspected was maybe crap pots? WD was the brand of the ones I bought and the ones out of the starcaster were alpha. Anyways, advice would be greatly appreciated. Also if you have actually read all of this that is greatly appreciated. Looking forward to doing a lot of these builds! Thanks in advance.
Try bypassing or disconnecting the volume and tone controls completely, as an experiment - if there is no longer any hum you have your answer and can trace it from there, but there will always be a little hum from volume and tone controls but not as bad as you describe. (-:
it is not mandatory to have tone and volume controls, try it without them...
I'd ditch the tone control I didn't think they worked with a piezo , I'd rewire it straight to the jack and see how that sounds if that's ok then it's your pots or your wiring .
The tone knob sounds like it's doing SOMETHING to the sound. Still no strings tho so idk yet. Frets came in today gonna hopefully have it done by tomorrow!
I did rewire the piezo straight to the jack and it sounded perfect. I would have used that method but I had already drilled holes in my box haha.
Hi Gary, if you could post a pic of your wiring it would help. Normally it isn't necessary to ground the strings with a piezo pickup. I have a suspicion there's an error in some of the wiring causing the buzz.
I personally would recommend having a volume control with a piezo - they can sometimes be a bit screamy, and this can normally be fixed by rolling the volume down a little.
I will post a pic in a few hrs after work. Keep in mind tho that the pots in there now came out of an old guitar I had. The only new soldering I did was wire to wire because I didn't want to burn up any more pots. It no longer buzzes like it was, just a faint hum that is only present up to about 9 or 10 on the volume knob. Also I have no pics of the old wiring, but I'll post some of the old pots I destroyed just to give you a little laugh at my garbage soldering. And would you also recommend a 1M ohm pot for piezo volume?
I've never had to ground the strings on a piezo pickup... mag pups, definitely...
I think your issue is the wiring/pots, etc. There's a thread here on using a vol/tone control on a Piezo. I'll have to find it...
What I recall is something along the line of: Piezos are a high-impedance device (around 1M Ohm) so you should use a 1M ohm pot for tone/vol. Also, the high end gets killed by the vol pot, so bypass the pot with a really small cap brings back the high-end...
If you don't use shielded wire, you can twist the wires together. That way, they both pickup stray EMF the same, which is then cancelled out. Keep wire runs as short as practical. Longer wires = longer antennae...
Truthfully, I've never found a need to put a vol pot on a piezo.. they don't have enough output to distort anyway.
Good things to keep in mind. If I decide to use another volume knob with a piezo in the future I'll be sure to try out the 1M/cap thing. I doubt I will tho, because I noticed while testing just piezo to jack that it sounded so much clearer. I really feel like I added the knobs for looks. That being the case I can just keep it at full volume and have a tone knob haha. Also I did twist the wire, I actually saw that in a thread on here as well, runs could probably be shorter tho. Thanks for the advice!
Replies
*Tone control in pointless on single piezo's, maybe on multiples
* Volume control is really handy for performance (use 1M pots)
* twist wires, tin tabs and backs of pots before soldering
replace on component at a time and resolder the hold thing. You can get bad/brand new components.
Try bypassing or disconnecting the volume and tone controls completely, as an experiment - if there is no longer any hum you have your answer and can trace it from there, but there will always be a little hum from volume and tone controls but not as bad as you describe. (-:
it is not mandatory to have tone and volume controls, try it without them...
image.jpg
I'd ditch the tone control I didn't think they worked with a piezo , I'd rewire it straight to the jack and see how that sounds if that's ok then it's your pots or your wiring .
I did rewire the piezo straight to the jack and it sounded perfect. I would have used that method but I had already drilled holes in my box haha.
Hi Gary, if you could post a pic of your wiring it would help. Normally it isn't necessary to ground the strings with a piezo pickup. I have a suspicion there's an error in some of the wiring causing the buzz.
I personally would recommend having a volume control with a piezo - they can sometimes be a bit screamy, and this can normally be fixed by rolling the volume down a little.
I've never had to ground the strings on a piezo pickup... mag pups, definitely...
I think your issue is the wiring/pots, etc. There's a thread here on using a vol/tone control on a Piezo. I'll have to find it...
What I recall is something along the line of: Piezos are a high-impedance device (around 1M Ohm) so you should use a 1M ohm pot for tone/vol. Also, the high end gets killed by the vol pot, so bypass the pot with a really small cap brings back the high-end...
If you don't use shielded wire, you can twist the wires together. That way, they both pickup stray EMF the same, which is then cancelled out. Keep wire runs as short as practical. Longer wires = longer antennae...
Truthfully, I've never found a need to put a vol pot on a piezo.. they don't have enough output to distort anyway.
I'll go look for that thread...