Replies to This Discussion

Permalink Reply by David L. on April 20, 2010 at 9:04am

Hi,

Regarding piezos there are no set rules - if you leave it in the case it may reduce the sound too much. If you use it bare many people use silicone mastic to fix it (I use serious glue which has a similar effect) so it dampens the pickup slightly because otherwise you pick up alot of unwanted noise (box rubbing against you for example). Best thing to do is try it both ways and see what your personal preference is. I buy mine off ebay UK (just search for piezo disc on ebay for example http://cgi.ebay.co.uk/5-35mm-Piezo-Elements-Sounder-Sensor-Trigger-... http://cgi.ebay.co.uk/5-27mm-Piezo-Elements-Sounder-Sensor-Trigger-...) and they come without a case with the 2 wires soldered on.

You do not need a volume control on your CBG - it just means you use the amp volume control instead.

Good luck,
David

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Permalink Reply by Richard Logston on April 20, 2010 at 9:46am

Thanks for the input. Richard

David Lloyd said:

Hi,

Regarding piezos there are no set rules - if you leave it in the case it may reduce the sound too much. If you use it bare many people use silicone mastic to fix it (I use serious glue which has a similar effect) so it dampens the pickup slightly because otherwise you pick up alot of unwanted noise (box rubbing against you for example). Best thing to do is try it both ways and see what your personal preference is. I buy mine off ebay UK (just search for piezo disc on ebay for example http://cgi.ebay.co.uk/5-35mm-Piezo-Elements-Sounder-Sensor-Trigger-... http://cgi.ebay.co.uk/5-27mm-Piezo-Elements-Sounder-Sensor-Trigger-...) and they come without a case with the 2 wires soldered on.

You do not need a volume control on your CBG - it just means you use the amp volume control instead.

Good luck,
David

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Permalink Reply by Mark on April 20, 2010 at 10:35am

Definitely take the disk out of the case (or buy disks that don't come in a case). That's because, for the best sound and output, the disk should be in contact with the soundboard (although a thin glue or mastic layer between disk and board is OK and can help damp out overly aggressive high frequencies and noise). Once the disk is fixed in place you might want to cover it with something like rubber foam matting as this can help reduce susceptibility to feedback.

I definitely recommend you fit a simple volume pot - it's really no trouble at all and it can be really handy if you find your guitar is a bit feedback prone (it's true you can use the input knob on an amp but you might come across an amp that doesn't have one and in any case a control on the guitar is more convenient).

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Permalink Reply by David L. on April 20, 2010 at 11:22am

If you want to add a volume pot this is the schematic link http://www.handmademusicclubhouse.com/photo/piezo-volume-jack?conte...

David

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Permalink Reply by Richard Logston on April 20, 2010 at 6:06pm

Thanks to everyone for your valued advice! I think I will add a volume control. One other QUESTION, I fear that tightening the strings will bow the upper end some. I'm thinking of a wooden brace as you would view it from the end it would form a tee re-enforcment under the neck in the cigar box.It would run up against each inside wall of the box and to prevent sound interference I would drill 3/4 holes evenly spaced from one end to the other. Comments please. Richard

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Permalink Reply by Jerryrig240 on April 21, 2010 at 6:24am

Here is my take on it...peizo's are a contact micrphone.....simple as that...if they don't make full contact with the box, you won't get great sound from them...now...a lot of guys take them from the case and samwhich them between foam, or use hot glue...me, I use hot glue and foam...I got too much of a banjo sound from my plain peizo' hot glued too the box...but that's just me. Anyhow, I do like my peizo' between some foam, it calms down the harsh feedback you can get every now then.;...that is my take on it....here is a little video that might help as well.

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Permalink Reply by Jason Hitesman on April 21, 2010 at 12:25pm

The contact microphone idea is a good way to look at it. But I kind of think of it one step further. Whatever the Piezo is attached to is turned into a microphone.

On my first CBG I glued the Piezo to the back of the box. It worked. But it almost picks up more noise from the box rubbing against my clothes than it does from the strings. And feedback? Woah, if I turn the amp up loud enough to be heard over the raw sound of the strings it starts feeding back BAD.

On my second I didn't glue the Piezo at all, I just kind of wedged it between the neck and the top where I had relieved the neck to give the top room to vibrate freely. The result was MUCH better. The signal to the amp was much louder and cleaner, it picked up less noise from my hands on the box, and I can barely get it to feedback at all even with the amp cranked and the CBG right up in front of the speaker.

I just did some upgrades to the second CBG (still working #'s 3, 4 and 5 as well but progress has been slow since I've been having too much fun learning to play #2.) and in the process moved the piezo so it's still wedged between the neck and the top. But now it's wedged tighter, and directly under the bridge. Now it's working great. The signal is finally loud enough at the amp to get some good crunchy distortion (it's a real quick and dirty home made LM386 based amp built out of a cheap old surround sound speaker.) it picks up even less noise from my hand on the neck, and I can now induce feedback if I try - but don't get the incidental feedback of CBG #1.

On the other hand CBG#1 also works kind of nice as a grungy microphone if you scream at the back of it, and #2 that trick doesn't work at all.

I haven't really tried mounting with any kind of foam yet. And with how well the placement on #2 is working I don't see myself needing to experiment with foams and glues until I attempt a build that doesn't have a through neck I can use to wedge the piezo against the back of the bridge with.

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Permalink Reply by Brian " BigB " Saunders on April 21, 2010 at 1:47pm

That sounds pretty cool Jason, I've been getting way too much feedback with anything I've been trying with my piezos. I'm building another CBG now and I'm gonna try your idea with the piezo. I hope if works out as well for me as it seems to have worked for you.
Again thanks for the info,
BigB

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Permalink Reply by Jerryrig240 on April 21, 2010 at 3:25pm

Good out look....I had never thought of it that way.


Jason Hitesman said:

The contact microphone idea is a good way to look at it. But I kind of think of it one step further. Whatever the Piezo is attached to is turned into a microphone.

On my first CBG I glued the Piezo to the back of the box. It worked. But it almost picks up more noise from the box rubbing against my clothes than it does from the strings. And feedback? Woah, if I turn the amp up loud enough to be heard over the raw sound of the strings it starts feeding back BAD.

On my second I didn't glue the Piezo at all, I just kind of wedged it between the neck and the top where I had relieved the neck to give the top room to vibrate freely. The result was MUCH better. The signal to the amp was much louder and cleaner, it picked up less noise from my hands on the box, and I can barely get it to feedback at all even with the amp cranked and the CBG right up in front of the speaker.

I just did some upgrades to the second CBG (still working #'s 3, 4 and 5 as well but progress has been slow since I've been having too much fun learning to play #2.) and in the process moved the piezo so it's still wedged between the neck and the top. But now it's wedged tighter, and directly under the bridge. Now it's working great. The signal is finally loud enough at the amp to get some good crunchy distortion (it's a real quick and dirty home made LM386 based amp built out of a cheap old surround sound speaker.) it picks up even less noise from my hand on the neck, and I can now induce feedback if I try - but don't get the incidental feedback of CBG #1.

On the other hand CBG#1 also works kind of nice as a grungy microphone if you scream at the back of it, and #2 that trick doesn't work at all.

I haven't really tried mounting with any kind of foam yet. And with how well the placement on #2 is working I don't see myself needing to experiment with foams and glues until I attempt a build that doesn't have a through neck I can use to wedge the piezo against the back of the bridge with.

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