Replies to This Discussion

Permalink Reply by HENRY LOWMAN on April 6, 2010 at 2:44pm

Cork has worked successfully for me too!

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Permalink Reply by Mark on April 20, 2010 at 10:14am

There should be absolutely no problem with two piezos in parallel.

Here's my twin piezo installation.

http://www.cigarboxnation.com/photo/twin-piezos-1
http://www.cigarboxnation.com/photo/twin-piezos-2

The pickups sit close to the two points where the bridge makes contact with the soundboard (I think you definitely want to be close to the bridge but not always necessarily right underneath - I'd agree with whoever said that sometimes there are mysterious "sweet spots" which you can best find by trial and error - but I need to experiment more with this). The theory behind the foam covering is that it insulates them a little from sound vibrations coming through the air thus reducing any tendency to feedback. Ideally they should work as contact mikes picking up vibrations in the soundboard.

At the moment I'm using a 500k pot and that seems fine.

Incidentally, here's a thought on which I'd be curious to hear opinions from anyone with better electronics knowledge than me...People have talked about problems of high impedance with piezos. But if you have the pot wired in the normal way for a volume control (as I do) then you effectively have a resistor (in my case adjustable up to 500k) in parallel with the pickups. Using the standard formula for resistance in parallel, this means that the amp's input sees a resistance of a bit less than the resistanc of the pot. I know impedance and resistance are not the same thing but in certain circumstances they can be treated similarly. So does the parallel resistance mitigate the impedance problems of piezos at all?

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Permalink Reply by Mark Myers on April 20, 2010 at 12:02pm

Ok totally off topic but did you build saddles for your neck to screw into at two points or did you glue it?

Mark aka. Junk Box Instruments said:

There should be absolutely no problem with two piezos in parallel.

Here's my twin piezo installation.

http://www.cigarboxnation.com/photo/twin-piezos-1
http://www.cigarboxnation.com/photo/twin-piezos-2

The pickups sit close to the two points where the bridge makes contact with the soundboard (I think you definitely want to be close to the bridge but not always necessarily right underneath - I'd agree with whoever said that sometimes there are mysterious "sweet spots" which you can best find by trial and error - but I need to experiment more with this). The theory behind the foam covering is that it insulates them a little from sound vibrations coming through the air thus reducing any tendency to feedback. Ideally they should work as contact mikes picking up vibrations in the soundboard.

At the moment I'm using a 500k pot and that seems fine.

Incidentally, here's a thought on which I'd be curious to hear opinions from anyone with better electronics knowledge than me...People have talked about problems of high impedance with piezos. But if you have the pot wired in the normal way for a volume control (as I do) then you effectively have a resistor (in my case adjustable up to 500k) in parallel with the pickups. Using the standard formula for resistance in parallel, this means that the amp's input sees a resistance of a bit less than the resistanc of the pot. I know impedance and resistance are not the same thing but in certain circumstances they can be treated similarly. So does the parallel resistance mitigate the impedance problems of piezos at all?

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Permalink Reply by Mark on April 21, 2010 at 12:27am

Mark Myers said:

Ok totally off topic but did you build saddles for your neck to screw into at two points or did you glue it?

The neck originally just sat in the box and was attached to the lid with a single screw (which is an arrangement that worked fine on a previous CBG). As a late-in-the-day design modification for this one I decided to fix the neck to the sides and/or back of the box, so I glued four small blocks of wood into the corners where the neck meets the sides - probably overkill but it makes for a more robust construction which ought to last better.

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Permalink Reply by Christopher on April 21, 2010 at 1:37pm

I don't have your problem at all. But I buy the RadioShack piazo busser and take the piazo completley out of the case. I super glue (Gorilla Super Glue) it to the inside of the box...volume is not a problem at all.

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Permalink Reply by Joker on May 8, 2010 at 12:52am

I have not read all the posts so I may be repeating something but the double piezo's I have installed sounded pretty good. They do produce a "weaker" signal but that also cuts down on feedback. I have found that they give you a louder and more even sound when installed directly below the bridge. The biggest problem with piezo sound quality I have found is not in the piezo's but in what your plugging into. Most guitar amps are designed to amplify a signal from magnetic pickups. Plugging in a piezo into one is like plugging in a mic to a guitar amp- feedback problems. I have found if you plug a piezo through a mic input on a mixer first you can better adjust your output. I plug all mine through a mixer then to a powered PA speaker. Listen to the vid below for an example- the guitar and footstompers all have piezo's running through a mixer to a PA

Find more videos like this on Cigar Box Nation

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Permalink Reply by Joker on May 8, 2010 at 12:55am

As far as wiring diagrams here is one that has been floating around since the first yahoo forum. If you do not want to install the volume and tone just wire the outputs straight to the jack

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Permalink Reply by Wes "I'm Baaaaack" Yates on May 8, 2010 at 2:15am

Good, but I would do the piezos in parallel. Series causes the impedence to double (additive). Parallel causes the impedence to half (division). Effect: MUCH better volume and tone:

-WY Joker said:

As far as wiring diagrams here is one that has been floating around since the first yahoo forum. If you do not want to install the volume and tone just wire the outputs straight to the jack

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Permalink Reply by Maddog on April 21, 2012 at 5:45am

I know this is an old thread but can anyone tell me which of the 2 diagrams on wiring 2 piezo's is best? I'm thinking in series like the bottom pic by Moaning Mule would be the way to go maybe?

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Permalink Reply by David L. on April 21, 2012 at 5:54am

The bottom one is the way I normally do it - it should be labelled in parallel though (both positives together and both negatives together).  I normally don't bother with a tone pot on piezo discs as they don't do much to the sound.

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Permalink Reply by Maddog on April 21, 2012 at 6:21am

Thanks David, I'll give that a lash.

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Permalink Reply by BenBob on April 21, 2012 at 6:43am

I don't understand all this talk about one or two piezo's. C.B. Gitty himself told me that for the best sound I should install at least eleven piezos in every guitar.

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