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Thread: Electric Mandolin Buzzing

  1. #1

    Default Electric Mandolin Buzzing

    I have this Saga electric mandolin kit. On completion I noticed an awful buzzing that abates when I touch the strings. I have taken step to add and improve the ground wires. I can confirm with a multi-meter continuity check that the strings are grounded to the amp ground plug. The nobs are also connected to this same ground.

    Assuming a coil issue I connected the multi-meter to the single coil pickups white and black wires. From what little I know there should be continuity in this connection and I should be able to move a piece of ferrous metal near the pickups and see a change in resistance. I do not see continuity in the two wires that come off of the pickups.

    Is the pickup faulty? If so, why does it amplify the strings when the mando is connected to the amplifier? Any help is appreciated.

  2. #2
    Registered User BoxCarJoe's Avatar
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    Default Re: Electric Mandolin Buzzing

    Sounds like 60 cycle hum.

    There are plenty of YouTube videos about this.

    It's usually shielding or grounding.

    Hope that helps.

  3. #3

    Default Re: Electric Mandolin Buzzing

    Is it the MT10 kit with a single Telecaster like pickup? I've embarrassed myself checking pickups with a multimeter, you do need to get resistance set to the right range or you see nothing.
    But as you are getting sound your pickup must be fundamentally OK.
    Firstly, have you another electric instrument you have plugged into the amp *with the same lead*, and find it behaving normally? Let's eliminate the rest of the system!
    Secondly does the hum change in volume if you move round the room and take the instrument closer or further from the amp. Have you tried carrying the whole lot to different rooms in the house or even outside.?

  4. #4

    Default Re: Electric Mandolin Buzzing

    Yes it is an MT10.

    I do not get the same buzzing from different instruments plugged into the same amp. A few different guitars sound without buzzing.

    Moving around the room, nor changing the pitch, roll, or yawl has any affect on the buzzing.

    Thanks for the tip on the multi-meter settings. That makes a difference! I do get resistance reading off of the pick-up.

    The tone knob did little to alter instrument sound so I disconnected that pot in my quest to eliminate the buzzing. That did not work. I have also lined the interior with aluminum foil to try to shield the instrument (although I did not coat the backside of the pick guard with aluminum foil).

  5. #5
    Registered User BoxCarJoe's Avatar
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    Default Re: Electric Mandolin Buzzing

    Quote Originally Posted by THX1138 View Post
    Yes it is an MT10.

    I do not get the same buzzing from different instruments plugged into the same amp. A few different guitars sound without buzzing.

    Moving around the room, nor changing the pitch, roll, or yawl has any affect on the buzzing.

    Thanks for the tip on the multi-meter settings. That makes a difference! I do get resistance reading off of the pick-up.

    The tone knob did little to alter instrument sound so I disconnected that pot in my quest to eliminate the buzzing. That did not work. I have also lined the interior with aluminum foil to try to shield the instrument (although I did not coat the backside of the pick guard with aluminum foil).
    Well you might know something I don't, but the shielding should be copper or that special paint they sell.

    https://www.stewmac.com/electronics/...pper-tape.html

  6. #6

    Default Re: Electric Mandolin Buzzing

    If you're not getting any change moving around IME it's unlikely to be shielding, radio pickup etc, so perhaps pointing at a wiring problem. You know, I presume that the foil needs to be connected to earth, hence popularity of copper. Is the pickup casing 0 ohms to earth?

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    Default Re: Electric Mandolin Buzzing

    Quote Originally Posted by BoxCarJoe View Post
    Well you might know something I don't, but the shielding should be copper or that special paint they sell.

    https://www.stewmac.com/electronics/...pper-tape.html
    The copper tape also needs to be folded over to make copper to copper contact....the bottom of the pickguard also needs to be shielded so that you are making a sealed copper box (a Farraday cage).
    You should be checking for continuity between all sheets. You should also solder a grounding wire from the harness/pot to the copper sheet somewhere in the cavity. Re-assemble and see if that helped. Then if the buzz still doesn't go away try removing the pickguard and touching the copper sheeting in the cavity to see if that grounds it. Not sure where to go from there.

  8. #8

    Default Re: Electric Mandolin Buzzing

    It sounds like a ground wire. Same as on an electric guitar. The easiest way to test is with the instrument plugged into an amp and then use a wire with an "alligator" clip at each end (these were available at Radio Shack for years -- not sure, if RS is still in business?) Put one clip on the nut of the input jack and then touch the other end to the strings and see if the buzz goes away. Then touch it to the bridge or tailpiece and see if it goes away. If it does you can solder a wire from the bridge or tailpiece to the back of the vol or tone pot or to the neg side of the input jack. That should solve the problem.

    Shielding is not the issue in this case, but can help make things even quieter once you solve the main grounding issue.

  9. #9
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    Default Re: Electric Mandolin Buzzing

    Aluminum works fine for shielding but it has to be grounded.

  10. #10

    Default Re: Electric Mandolin Buzzing

    Quote Originally Posted by Nevin View Post
    Aluminum works fine for shielding but it has to be grounded.
    Aluminium, steel or any other metal for that matter. As long as it forms a Faraday cage.
    Altoids tins etc are common for guitar amps or effects for that reason.

  11. #11

    Default Re: Electric Mandolin Buzzing

    Quote Originally Posted by JimCh View Post
    If you're not getting any change moving around IME it's unlikely to be shielding, radio pickup etc, so perhaps pointing at a wiring problem. You know, I presume that the foil needs to be connected to earth, hence popularity of copper. Is the pickup casing 0 ohms to earth?
    The pickup is removed from the instrument completely. I can connect an ohm meter to the negative wire from the pickup and I get no continuity to any part of the pickup casing.

  12. #12

    Default Re: Electric Mandolin Buzzing

    Quote Originally Posted by Jeff Mando View Post
    It sounds like a ground wire. Same as on an electric guitar. The easiest way to test is with the instrument plugged into an amp and then use a wire with an "alligator" clip at each end (these were available at Radio Shack for years -- not sure, if RS is still in business?) Put one clip on the nut of the input jack and then touch the other end to the strings and see if the buzz goes away. Then touch it to the bridge or tailpiece and see if it goes away. If it does you can solder a wire from the bridge or tailpiece to the back of the vol or tone pot or to the neg side of the input jack. That should solve the problem.

    Shielding is not the issue in this case, but can help make things even quieter once you solve the main grounding issue.
    I have soldered a wire from the tailpiece (through the body of the instrument) and connected that to the ground of the rest of the components. Before removing the pickup I can confirm that there was continuity between the tailpiece, the amp plug, the strings, and the volume nob ground.

  13. #13

    Default Re: Electric Mandolin Buzzing

    Im not quite clear on your current status. You have pickup removed completely, otherwise all wiring complete, and you get loud buzz when plugging instrument to amp?

  14. #14
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    Default Re: Electric Mandolin Buzzing

    Quote Originally Posted by THX1138 View Post
    I have soldered a wire from the tailpiece (through the body of the instrument) and connected that to the ground of the rest of the components. Before removing the pickup I can confirm that there was continuity between the tailpiece, the amp plug, the strings, and the volume nob ground.
    If you have a tone control you need to ground that too. If you are plugging it in with the p/u out it may buzz even grounded as there is no shielding. Sometimes an appliance running or light on a dimmer on the same circuit will cause buzzing, have you tried a different circuit in the house.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

  15. #15

    Default Re: Electric Mandolin Buzzing

    Here is what you want. Ground everything directly to the volume pot including the shielding. Do not create a loop. With all that said, that pickup is going to hum no matter what because of its quality and the fact that it is a single coil. Your best bet is to get a humbucker and new pots.

    I would highly recommend an Almuse humbucker.
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