I am adding a piezo pickup from CB Gitty to a new build. I understand they can be hot sounding when not shielded, which brings me to my question. If I were to make my own disc-o-tone, are both sides of the piezo covered in wood? If not, should the brass disc or the ceramic disc face the soundboard?
Many thanks!
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The disco-tone from CB gitty is embedded in a hardwood that looks like oak, but Bad Finger is right that the wire side is cork. From what I can see on the one that I have, there is some sort of silicone or hot glue buffer between the actual piezo and the cork and I would imagine it's is covering the entire piezo. The instructions tell you to put the hardwood surface on the underside of the sound board near the bass side of the bridge (so corkside down). The hardwood has double sided tape already attatched to it to affix to the sound board.
As mentioned below, CB Gitty has probably done a lot of experimenting and the time attempting to replicate this will likely not be worth the extra few dollars.
Scott W > Barsymes CratchneeJanuary 10, 2014 at 12:33pm
Thanks to everyone for the advice. I agree about CBGitty having done trouble-shooting. However, I had already purchased from them a piezo pickup kit, then discovered they should be shielded to dampen the treble tones.
The piezo is shielded with hardwood, foam, and foam mounting tape. It sounds great, except I am having a bit of a problem with a volume control. I am happy with the pickup arrangement, though.
Piezo elements have a really high impedance, like near 1M ohm. Using a small pot won't work, you need to use one that is at least 250k, if I recall... it's around here somewhere.
Your best bet is to use a buffer/booster and set the volume there. You could install a 9V buffer IN your CBG, if you know a little electronics. Google Jfet preamp.
if the piezo is sandwiched in wood, it probably doesn't make any difference it's orientation vis-a-vis the soundboard. If it is embedded in wood with only one side exposed, I would definitely orient the the brass toward the wood (away from the soundboard). I've build plenty of "martin style" bridges, with piezo embedded brass side toward the void on the underside of the bridge. before gluing the bridge in place, I cover the ceramic side with silicone caulk. the arrangement cuts out feedback and lessen top noise.
Both sides are embeeded in wood, although the wire side appears to be cork on the Amazon.com pictures. I don't think it will matter much which faces the soundboard, but you might experiment both ways. It will be more important that you have the disc tightly and evenly laminated within the wood case, which I suppose is one of the reasons why there's cork on the back side.
Of course, CB Gitty has done a bunch of the trial and error for you already. Might be worth just paying the few extra bucks for the prewired set up with volume control.
Scott W > Bad Finger (Eric)January 6, 2014 at 12:53pm
I probably would have just picked one up from CBGitty had I realized, but I am new to CBGs and new to pickups. Cork and craft foam happen to be both on hand, so I will do a little fiddling around. Thanks for the help!
There are a bunch of ways that piezos are used. Some just embed them in a gob of hot glue, some potted in bottle caps with silicone, some just foam double side tape to the soundboard (I've done this one). I remember someone just wrapping the disc in tissue or cotton rag and leaving it loose in the box.
Replies
The disco-tone from CB gitty is embedded in a hardwood that looks like oak, but Bad Finger is right that the wire side is cork. From what I can see on the one that I have, there is some sort of silicone or hot glue buffer between the actual piezo and the cork and I would imagine it's is covering the entire piezo. The instructions tell you to put the hardwood surface on the underside of the sound board near the bass side of the bridge (so corkside down). The hardwood has double sided tape already attatched to it to affix to the sound board.
As mentioned below, CB Gitty has probably done a lot of experimenting and the time attempting to replicate this will likely not be worth the extra few dollars.
I will post the results later. Thanks again!
image.jpg
Piezo elements have a really high impedance, like near 1M ohm. Using a small pot won't work, you need to use one that is at least 250k, if I recall... it's around here somewhere.
Your best bet is to use a buffer/booster and set the volume there. You could install a 9V buffer IN your CBG, if you know a little electronics. Google Jfet preamp.
if the piezo is sandwiched in wood, it probably doesn't make any difference it's orientation vis-a-vis the soundboard. If it is embedded in wood with only one side exposed, I would definitely orient the the brass toward the wood (away from the soundboard). I've build plenty of "martin style" bridges, with piezo embedded brass side toward the void on the underside of the bridge. before gluing the bridge in place, I cover the ceramic side with silicone caulk. the arrangement cuts out feedback and lessen top noise.
Both sides are embeeded in wood, although the wire side appears to be cork on the Amazon.com pictures. I don't think it will matter much which faces the soundboard, but you might experiment both ways. It will be more important that you have the disc tightly and evenly laminated within the wood case, which I suppose is one of the reasons why there's cork on the back side.
Of course, CB Gitty has done a bunch of the trial and error for you already. Might be worth just paying the few extra bucks for the prewired set up with volume control.
There are a bunch of ways that piezos are used. Some just embed them in a gob of hot glue, some potted in bottle caps with silicone, some just foam double side tape to the soundboard (I've done this one). I remember someone just wrapping the disc in tissue or cotton rag and leaving it loose in the box.
https://www.cbgitty.com/cubecart/c-b-gitty-disc-o-tone-piezo-pickup...