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Permalink Reply by joel peksujeff on April 11, 2016 at 7:14am

also, one more question:

what kinda output levels i should expect from a piezo in general,

i have my knobs up in eleven to hear a decent signal, is this normal. i have one volume

pot between the piezo & jack...

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Permalink Reply by JL on April 12, 2016 at 12:29am

No it's not normal, piezo's are hot!.   My single disk piezo GBCs have plenty of "level"  with the volume pot turned to about 1/3, and the 10w practice amp volume turned to about 1/4 to 1/2 depending on the room and I get more than enough volume.  Though I haven't yet tried multi-piezo yet.

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Permalink Reply by Rick Alexander on April 11, 2016 at 8:47am

I made a couple discs like the disc-o's, and they work well, but are far inferior to rod piezos. If you want to make it yourself, use a piece of fretboard scrap, hollow out a cavity for the disc, and top it with cork. Use that double stick foam to attach it, like RTZGuitars pic, and put it under the bass leg of your bridge (inside)with the cork side facing the void. 

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Permalink Reply by Fomhorach on April 11, 2016 at 11:31pm

If you wire 2 in serial, they might cancel out the high frequencies. Since your box is metal I guess it's the high freq that are problematic. Also, make sure your lid is firmly attached. If it's moving about a bit then it might not be a piezo problem at all.

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Permalink Reply by joel peksujeff on April 11, 2016 at 11:48pm

hmmm, for some reason two piezos both in series and parallel cut only volume, i added a third one

and that made things a bit better. still had a load of handling noise, though.

so i rewired the whole damn thing just to be sure. now i have one stainless steel piezo,

it's quite a bit hotter, but the handling noise somehow has'nt increased as much as one would expect. so i'll try to find a good spot for it now. we'll see what happens...

and as for the lid i have window sealing tape keeping it in place :)

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Permalink Reply by Fomhorach on April 11, 2016 at 11:53pm

Good luck. Let us know how it comes along as good tips travel well.

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Permalink Reply by bemuzic on April 11, 2016 at 11:59pm

another option is to see  the "unwanted noise" in a different way : - )    http://www.cigarboxnation.com/video/unwanted-noise

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Permalink Reply by Del Puckett on April 12, 2016 at 4:19am

i have found that taking a "plastic water bottle cap" and hot glueing over the top of the piezo (creating an air gap) helps.  

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Permalink Reply by Domino on April 12, 2016 at 6:16am

I put a 100nf capacitor in line on the positive side of piezos to reduce noise from knocks. Loosely based on a passive high pass filter: http://www.electronics-tutorials.ws/filter/filter_3.html though I can't remember why I didn't bother with a resistor :)


Full details of my crazy electronics are in the build thread comments: http://www.cigarboxnation.com/profiles/blogs/rough-cuts-and-adjusta...

Mostly designed by experiment rather than any knowledge of what I was doing :)

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Permalink Reply by joel peksujeff on April 12, 2016 at 8:02am

okay, i've finally settled with something... after ten different caps and discs i now have 

a 2cm brass piezo between two pieces of cork, cut from a wine bottle

sandwiched between the soundboard and the tableleg by a lid from an old class container

and a lid from a moustache wax tin.

it sounds good, with as much handling noise you would get recording with a dynamic mic.

demonstration coming soon(ish).

the output level seems to increase soon as i clue/tape/what ever the thing to its place, maybe because less resonation?

Attachments:

• IMG_20160412_214959.jpg, 841 KB

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Permalink Reply by JL on April 13, 2016 at 1:13am

piezo signal strength is in direct proportion to how solidly the vibrations are conducted to the crystal layer of the disk. 

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Permalink Reply by joel peksujeff on April 13, 2016 at 2:54am

that would make sense, but WHY does it work the opposite.

i am puzzled.....

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