Annoying Hum

I've just completed my first build and after some tweaking with the nut and bridge to get the string height correct I went to plug into the amp, there is this annoying hum/buzz which clears when i touch the metal volume control knob. Can anybody help resolve this issue.....i've used a piezo pick up glued to the underside of the cigar box lid under the key which i'm using as bridge. Thx

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Replies

  • My suggestion is to ditch the volume pot all together. I don't use controls on my CBGs ..... the volume is on the amp, and tone is useless on a piezo unless pre-amped.
    No humbuzzies ever.

     

     

    Matt

  • Those mini pots are really suseptable to heat damage. Try to keep your heats to the minimum time necessary to get your solder and wires down. Also, are you sanding the surface area of your pot before putting down your puddle for your grounds? If you over heat your pot you may damage it and it can cause a hum or other noises in your circuit.

     

    Good luck with the new pot.

     

    Brian Hunt.

     

  • So I have heard this with every thread about Piezo's...they do not require a ground. I suggest using a new piezo before spending the money on a pot. Make sure you have no cold joints, I had the same issue with a build, the buzz went away when the volume was turned past 8 or so. I tried all kinds of things. A new piezo fixed it. Just one case though. Might be different with you.

  • Thx for the reply I've now checked the soldering and earthed the key as suggested but still no luck, now the Vol Pot doesn,t work somaybe that was the problem. I've ordered a new 250K mini pot so fingers crossed I may resolve my issue.

     

    Regards Chris


    Brian Hunt said:

    If you are grounded correctly, you could have a cold solder joint that can also cause a hum. Also, keep your connection wires as short as possible so they don't act like an antena and pick up 60 cycle hum from your lights or something. Using shielded wire can help stop the 60 cycle hum issues.

     

    Where the hum dissapears when you touch the volume know I would guess you either have a ground problem like Matt said, or you have a cold solder joint.

     

    Brian Hunt.

     

  • Hi Brian,

     

    Thx for the reply I've now checked the soldering and earthed the key as suggested but still no luck, now the Vol Pot doesn,t work somaybe that was the problem. I've ordered a new 250K mini pot so fingers crossed I may resolve my issue.

     

    Regards Chris

    Artist Formerly Known as Matt said:

    Your volume pot needs a ground wire to the jack ( at the very least).

    Probably need to run a ground wire to the key bridge also.

    When you touch the volume knob you are grounding it causing the noise to go away.

    The wire should go from the metal case to the control lug to the jack to the bridge.

     

    VolumePotDia.jpg

     

     

    AFKAM

  • If you are grounded correctly, you could have a cold solder joint that can also cause a hum. Also, keep your connection wires as short as possible so they don't act like an antena and pick up 60 cycle hum from your lights or something. Using shielded wire can help stop the 60 cycle hum issues.

     

    Where the hum dissapears when you touch the volume know I would guess you either have a ground problem like Matt said, or you have a cold solder joint.

     

    Brian Hunt.

     

  • Your volume pot needs a ground wire to the jack ( at the very least).

    Probably need to run a ground wire to the key bridge also.

    When you touch the volume knob you are grounding it causing the noise to go away.

    The wire should go from the metal case to the control lug to the jack to the bridge.

     

    VolumePotDia.jpg

     

     

    AFKAM

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