Dual Piezo wired in parallel with 500k vol pot problem

Posted by Dazedlemonpie on July 15, 2011 at 7:50am

Hi Nation,

 

I made a fairly sweet sounding cbg with 2 piezo wired in parallel and added a 500k vol pot, works great no noise whatsoever if i have the vol pot turned all the way to the max, but when i back it down to say half way, it starts to have feed back, does anyone know what i did wrong ?

appreciate your advises

cheers and peace

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Replies

  • Malcolm Haines July 23, 2011 at 12:26am

    Hi,

    thanks for showing interest in my info. Makes me feel good. Advice at this stage is to try a pot with lower resistance (say around 200k)  and wind your gain on the amp right down. This seems to work, so I am looking into the characteristics of the Gain control. Another electronics friend suggested a fixed value resistor in line and in front of the Pot. If you are using a 500k pot, a little movement on the knob can represent a large jump in resistance. The fixed value resistor and the lower value pot will allow lesser changes in the current running through to the output jack. Also, different brands of pots are differing qualities too.

     

    peace

    Dazedlemonpie said:

    Hi Marcolm,

     

    tks for sharing, i am not the most seasoned electrician, so my soldering techniques are mostly from youtube (lol). So if the off the shelves you purchased has the similar problem, then it might be something entirely different than i thought ( cold solder joint or whatever its called). I have another friend who told me that it might be the a bad pot, so i might try another pot hence try to do a better soldering job this time. The reason i wanted a vol, is to be able to control the tone of the cbg right at arms length, just like i am used to on a regular elec. Especially if i have say a Tube screamer in the effect chain, i can have less or more saturation tone just by dialing in the vol pot. So thats important to me. Another thing is the piezo itself is really a lofi speaker, you cant really expect it to perfom like a magnetic pickup. I recently purchased a under the saddle piezo rod pickup, i will give that a go and see if vol pot and rod piezo would make better friends.

     

     

  • Dazedlemonpie July 21, 2011 at 1:35am

    Hi Marcolm,

     

    tks for sharing, i am not the most seasoned electrician, so my soldering techniques are mostly from youtube (lol). So if the off the shelves you purchased has the similar problem, then it might be something entirely different than i thought ( cold solder joint or whatever its called). I have another friend who told me that it might be the a bad pot, so i might try another pot hence try to do a better soldering job this time. The reason i wanted a vol, is to be able to control the tone of the cbg right at arms length, just like i am used to on a regular elec. Especially if i have say a Tube screamer in the effect chain, i can have less or more saturation tone just by dialing in the vol pot. So thats important to me. Another thing is the piezo itself is really a lofi speaker, you cant really expect it to perfom like a magnetic pickup. I recently purchased a under the saddle piezo rod pickup, i will give that a go and see if vol pot and rod piezo would make better friends.

  • Malcolm Haines July 20, 2011 at 2:09am

    Hi

    I bought a piezo/pot/jack wired up and machine soldered from ebay for 12 bucks (it cost me $9 in parts here in OZ, then there's the time to make it). I have tried one out placing it in an mint tin and putting it at the end of a diddley bo under the string. I get a similar effect, the closer to full rotation of the pot, the less noise. I've found a sweet spot that makes a great noise, so it stays there and all the volume is handled by my amp. I have a double piezo in parallel and will be trying to install it into my CBG. I thought I had finished an acoustic resonator, but now need to undo everything to get the new pickups in. The pickups from this company are sheathed in wood and look like a part of a CBG should. The supplier is prfromil.

    peace

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