Buzz/hum

I have just wired up my lovely new rod biscuit pick up from Randy Bretz and have encountered an oddity to my experience. Everything work just fine but I have found that I weirdly get MORE buzz when I am touching the strings or metal bits! When I let everything just lay there, untouched the circuit is pretty quiet. Seems odd to me...counter intuitive to my mind. I'm sure it's something unique to my build. The 500k volume pot body is grounded to the neg input tabs, the 3rd pot post and to the output jack...as per classic piezo and volume wiring diagrams from CB Gitty's site...just seems weird. Anyone have any ideas on why this might be?

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  • Fair enough, at least I don't feel like I'm totally operating in the twilight zone! Thanks Ted. I think I have to schedule some time with one of my little alligator clip jump leads and see what wants earthing to where!
  • Tom,

    Shielding shorted on the cone, created a large pickup. You touching the strings created an even larger antenna. Electricity is weird that way. Glad you solved it.
    • Yeah, I think a length of thin heat shrink will quiet everything down nicely. I'm glad I had a moment of clarity.
      • From now on with your idea on the rod wire , I am using a length of small heat shrink on the rod wire from the rod to an 1" past the dowel. Sorry Tom, but with your discovery of this problem has helped me improve the design.

        • I was glad to take a temporary bullet for the team! Hahahaha!
          • Ok...just when I thought it was safe to strum the strings.....

            I'm still getting a humm when I touch the strings or metal bits!!!

            How the %#*€ can this be?!

            The piezo shield wire is entirely insulated. There is not a SINGLE BIT of the electronics touching anything metal....AT ALL! Even the bridge is bone!

            What the HELL!?
            • Hmmm. So you get a hum when you touch the strings...it doesn't go away when you do that, right?

              • There is a bit of a buzz/hum without touching the strings...when I touch them it gets more pronounced.

                Again they and nothing they touch is actually connected in any way to any electrics...at all!

                Could this be an "antenna" type situation? EM issue? Ghosts?
                • gotta ground the strings and the cone...or the buzz will never go away

                  • same thing w/ standard electric guitar...strings don't touch electronics or pickup, but they do attract electrical fields (lights, tv & radio signals, etc) and that is as you said earlier, "an antennae effect.

                    Not sure why the shield of the piezo wire touching the cone would magnify the humming noise, unless there is a pinched/broken internal (positive) wire that is crossing over to the negative/ground/earth. Strange indeed.

                    But fact is, grounding strings will eliminate any noises (other than music) that the strings are attracting and sending to amp.

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