more piezo issues , imagine that

so i am working out the bugs on my first build , i re-set 2 frets that were a lil high .

tested it with 2 homemade amps .

its humming . i have a single piezo . now the odd thing is when it touch the jack = no hum , and when i touch the strings = no hum . its just demonic cause i cant see were the strings are in contact with the ground at all !

i guess i should check the grounds . i know the ground on the volume pot is a lil shady , prolly cold , but what the ????

any way the output is low , i mounted the piezo inside the lid of the box , under the bridge , between the neck and the lid . i cut a cavity out of the neck for the piezo / wire , and filled that with hot glue like a dummy . (que fred sanford https://www.youtube.com/watch?v=S7l3EtIC4j0 )

i am hoping its not a bad connection on the piezo itself . i guess i could always ground the bridge , but .

the low out put is a real drag though , i guess i will build a premp circuit / 9volt and mount that in the guitar . i have been reading about this topic all night and can not make up my mind . i may try adding a second piezo , but that sounds too good to be true .

any one try those dolla stow window alarm piezos ? how do they stack up , is there a difference ? any way of testing these things before using em ? i spose you could hook em up to an amp and see if you can hear a difference but that seems like it would be tough to get a constant .

the one side of me is wanting to run to rat shack for these parts tomorrow

http://www.cigarboxnation.com/group/amps/forum/attachment/download?id=2592684%3AUploadedFi38%3A5426

the other side of me says place an order for the more affordable parts / best supposed quality here :

http://www.till.com/articles/GuitarPreamp/index.html

is any one familiar with the top circuit that uses the radioshack jfet ?

any tips on this preamp business ?

i guess i will be putting these circuits in all my builds , cuz it still is way cheaper than using a mag pup . we are broker than broke .

any advice on this hum and preamp stuff is much apreciated , sincerely , petey 2 .

the 2 fingered guitarist (lawn mower) .

You know, I just got the fix done on my CBG. I use a piezo straight to the 1/4" jack. The hum I had was tolerable usually but then I started using a amp modeler and some of the selections had more noise than I wished. I could not understand why grounding would do anything positive for my CBG. So I went ahead and did it. I improved the wiring from the jack with a shielded wire connecting the shield to the sleeve as well as the the one conductor. The other conductor connected to the tip. I also installed a stainless steal butt plate where the jack was more firmly mounted. I connected a wire from my jack mounting to the bridge ( easy enough as my bridge is a 5/16" threaded rod with nuts that lift the strings to just the right level). I really thought much of this was overkill.

Now I plug in and most all the bad noise has left. With the amp modeler, I can play the high gain stuff. I don't understand why it works, but it does.

Replies

charles kimbler May 23, 2010 at 9:01am

I just built another guitar.I used a 35mm piezo set in a bed of hot glue.I put down a puddle and place the piezo wire side up on the sound board and press down pretty hard until the glue sets.You don't have to cover the side of the piezo a lot.I can turn my amp up a 10th of the way and it's blasing.I think this is the best way to use a piezo I have found.As far as your buzz you need to use 5k pots.They work the best on piezos.Go to radio shack and they cost 2.99.You will have to cut the shaft to lenght as they come with a long one.I found out the hard way that a 500k pot is just wrong.
petey twofinger May 21, 2010 at 11:12pm

built a preamp today , sounds great , solved the low output issue .

i determined the hum is comming from the amp , i guess .

i will be mounting the circuit tomorrow and do some more monkeying .

its gonna be 85 here on sumday , want to go to the woods and relax , a lil bbq , music , sunshine .

cant wait , hopefully we wont run into the tree pig that shut my wife and our kids jam session down there 2 years ago .
he wanted a permit , for a casio , a bass , guitar , mic , and some lil amps / karoake machines .

his specific words were " Yall cant beez havnin CONTRAPTIONS in the forest preserve ".

i had some cell phone chargers cut into a deep cell for power . he said that bat-tree is fittin to axploat .

fat f'n p^& son of a b@*&h %@$$3R
Bluesheart May 21, 2010 at 9:42pm

I don't know where the hum is from, likely a bad solder join as you said. I used the dollar store window alarm piezo in my last build and it sounded great through my buddy's bens jens acoustic amp. I heard no diff in it vs the more expensive ones, maybe even better. A bonus was that the 3 small batteries fit the laser pointer we use to drive the cats nuts! I save the micro switch too and will use it on something. Thats a lot of bang for a buck!
Bluesheart
Train train May 21, 2010 at 7:41pm

You know, I just got the fix done on my CBG. I use a piezo straight to the 1/4" jack. The hum I had was tolerable usually but then I started using a amp modeler and some of the selections had more noise than I wished. I could not understand why grounding would do anything positive for my CBG. So I went ahead and did it. I improved the wiring from the jack with a shielded wire connecting the shield to the sleeve as well as the the one conductor. The other conductor connected to the tip. I also installed a stainless steal butt plate where the jack was more firmly mounted. I connected a wire from my jack mounting to the bridge ( easy enough as my bridge is a 5/16" threaded rod with nuts that lift the strings to just the right level). I really thought much of this was overkill.

Now I plug in and most all the bad noise has left. With the amp modeler, I can play the high gain stuff. I don't understand why it works, but it does.
Outhouse Instruments May 21, 2010 at 4:15pm

Ground issue. When you touch the stuff and the hum goes away. ground issue. really no need for a pre-amp. Dig the piezo out, check the ground or just re-solder everything.
You might consider taking the volume pot out of the picture and check all grounds just to see if the hum goes away.

Matt
Roger Morin May 21, 2010 at 5:03am

C.B. Getty has cheap piezos for sale and he is a member here. Look on the left side front page all the way to the bottom or on the right uner bluesboy Jag
Roger Morin May 21, 2010 at 4:58am

More than likly you have a bad solder joint, the best way to mount a piezo is with hot glue lay down a puddle put doen piezo cover with more hot glue. I have owned many instruments from Jay at tinyguitars and they all sound great, thats the way he does his piezos.
petey twofinger May 21, 2010 at 12:10am

https://www.youtube.com/watch?v=eu5FF5BkrwY

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