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  • Shielding a guitar - hum persists

    Evening, gents.

    I've got here a nice '89 Gordon Smith GS1.5 that I've just lovingly shielded, but the sneaky guit-fiddle still insists on humming. It's the sort of hum that disappears when you touch the strings or any other grounded metal part, so it would seem my shielding job was inadequate. Thus, a question to those with experience in this - would any of the following reintroduce so much noise as to completely foil a shielding attempt?

    1) the pickups aren't shielded (even the humbucker's cover is plastic). They also sit fairly high out of the body as the guitar is a flattop. I'm hesitant to shield the pickups themselves, as the guitar's kind of old and actually belongs to a friend, so any damage to the pickup windings would be Very Bad
    It's a well-known fact that 100% of people who sell their Telecasters, die.

  • #2
    If the hum stops when you touch the strings then you most likely have a problem with the bridge ground wire .

    Comment


    • #3
      My thought exactly. Hum is much more often a grounding issue than a shielding issue. I have solved similar sounding problems several times by cleaning or replacing the output jack, and at least once by cleaning the bridge grounding lead.
      "The Web puts all of the world's knowledge at our fingertips; unfortunately it's mixed with all of the world's bull****************."
      -- Bob Parks

      "A thing is not necessarily true because a man dies for it."
      -- Oscar Wilde

      "No man dies for what he knows to be true. Men die for what they want to be true, for what some terror in their hearts tells them is not true."
      -- Oscar Wilde

      "It is a trap of history to believe that eyewitnesses remember accurately what they have lived through."
      -- Theodore White

      Comment


      • #4
        If the hum stops when you touch the strings then you most likely have a problem with the bridge ground wire .


        x2

        Also stwemac sells some copper paint that I like better than the tape for shielding. Easier to fit into different places than the tape.
        Spam:
        Voodoo SuperBass and Pre-pro Hex

        Gear:
        '84 Gibson Les Paul Studio
        '78 Gibson RD Artist: De-mooged, WCR Crossroads/Darkburst
        '74 Gibson SG Deluxe: Rio Grande P90's

        Marshall Super Bass: Voodoo Modded
        Voodoo Amps 50w Hex
        Orange Tiny Terror

        Comment


        • #5
          Le sigh...

          The bridge ground wire is fine. If it weren't, touching the strings would have no effect on hum (except for perhaps making it even louder). And yes, I checked it with an ohmmeter.

          Also stwemac sells some copper paint that I like better than the tape for shielding. Easier to fit into different places than the tape.

          That's nice. I prefer tape, as it can be soldered to, and is less permanent than paint.
          It's a well-known fact that 100% of people who sell their Telecasters, die.

          Comment


          • #6
            Le sigh...

            The bridge ground wire is fine. If it weren't, touching the strings would have no effect on hum (except for perhaps making it even louder). And yes, I checked it with an ohmmeter.


            When you touch the strings your body acts as a ground and the hum/buzz stops. If this is what's happening then your guitar is not grounded properly. If the hum became louder when you touched it then it would mean something is wired backwards. Use your ears not your ohm meter.

            Comment


            • #7
              And how, pray tell, are you grounding the guitar? Are you standing barefoot on a metal plate? Or touching a water pipe, perhaps?

              Your body acts as a shield, and the guitar is grounding you.

              Your body, on account of being much larger than the wiring inside the guitar, picks up noise much better. When you're simply holding the guitar without touching any grounded metal parts, you simply radiate any noise you pick up right into the guitar's wiring. Hence the noise. As soon as you touch a grounded metal part on the guitar (such as the strings), you're grounded through said metal part, and the noise will disappear, as it's being shorted to ground. This is why shielding the guitar should help, as it'll provide a permanent, always-grounded layer of protection between the noise and the guitar's circuitry.

              Here's a couple of fun experiments to try. Plug your guitar into your amp and turn it up. Don't touch any metal parts. Unless your guitar is well shielded, you should hear some noise. Now place your hand over any of the pickups, while still avoiding the strings. The noise should increase. Try moving your hand closer to, say, a computer monitor. The noise should increase even more. Now put the guitar away from your body (while it's still plugged in). The noise should decrease. This shows how your body is acting as a channel for noise. And unless there's another shield in place between you and the guitar, you'll have to ground yourself through the guitar to avoid bleeding that noise into the circuitry.

              Also, when you touch the strings and the hum increases, it's a sign that the bridge (and hence the strings) isn't grounded. The reason is that you're inserting the noise into the strings, which in turn concentrate it right above the pickups (which are extremely effective antennae), rather than sending it to ground via the bridge.

              Now, does anyone have any helpful suggestions?
              It's a well-known fact that 100% of people who sell their Telecasters, die.

              Comment


              • #8
                I have a great suggestion....

                Touch the strings, while holding your guitar.

                I know it sounds simple, but it works.

                As for the shielding... if you have less interference, static, and random noise, your shielding is proper.


                BTW, buy a noise gate. It works when not touching the strings.oke:

                Comment


                • #9
                  I have a great suggestion....

                  Touch the strings, while holding your guitar.

                  I said, helpful suggestions. If that sufficed, I wouldn't have bothered with the shielding in the first place.

                  As for the shielding... if you have less interference, static, and random noise, your shielding is proper.

                  As I explained in the first post, the guitar still gets hum, therefore the shielding wasn't proper. Hence this whole thread.

                  Honestly, is it so hard to understand what I'm asking for?

                  BTW, buy a noise gate. It works when not touching the strings.oke:

                  Yeah, and having it clamp down on long sustained notes is ever so nice.
                  No, thanks. I want to kill the hum at the source, before it gets into the signal chain.
                  It's a well-known fact that 100% of people who sell their Telecasters, die.

                  Comment


                  • #10
                    Seriously dude quit being a dick.

                    Star ground, shield everything you can and don't play near florescent lights or computer monitors. If it's really that big of a deal you could redo the wiring from the neck pickup with a shielded one...

                    You said yourself you didn't completely shield everything, so thats where I would personally start.
                    Spam:
                    Voodoo SuperBass and Pre-pro Hex

                    Gear:
                    '84 Gibson Les Paul Studio
                    '78 Gibson RD Artist: De-mooged, WCR Crossroads/Darkburst
                    '74 Gibson SG Deluxe: Rio Grande P90's

                    Marshall Super Bass: Voodoo Modded
                    Voodoo Amps 50w Hex
                    Orange Tiny Terror

                    Comment


                    • #11
                      Seriously dude quit being a dick.

                      Right, I'm sorry for getting upset at the fact that all the suggestions presented in this thread so far, while well-intended I'm sure, have been irrelevant at best and grossly misinformed at worst. Sorry for trying to re-elaborate my problem in what I thought was a fairly calm and polite manner. Sorry for actually taking the time to educate the would-be helpers and pointing out their mistakes. Sor-ry.

                      Star ground, shield everything you can and don't play near florescent lights or computer monitors. If it's really that big of a deal you could redo the wiring from the neck pickup with a shielded one...

                      As I explained in the first post (I feel like I've said that already), it's not my guitar, and it's kind of old, so I don't want to touch the pickups if at all possible. Also, the owner of the guitar will inevitably be playing near sources of noise, so that suggestion of yours has little merit.

                      Re star grounding, how exactly is that going to help me?

                      You said yourself you didn't completely shield everything, so thats where I would personally start.

                      The first actually useful suggestion in this thread so far. Thank you, sir, you have given me hope again (and that wasn't sarcasm).

                      Now, is it your experience that the guitar's electronics have to be completely enclosed? Would even the smallest hole in the shielding reintroduce all the noise? If so, how would you suggest I shield the channels that the pickup wires run through?
                      It's a well-known fact that 100% of people who sell their Telecasters, die.

                      Comment


                      • #12
                        Right, I'm sorry for getting upset at the fact that all the suggestions presented in this thread so far, while well-intended I'm sure, have been irrelevant at best and grossly misinformed at worst. Sorry for trying to re-elaborate my problem in what I thought was a fairly calm and polite manner. Sorry for actually taking the time to educate the would-be helpers and pointing out their mistakes. Sor-ry.


                        There you go being a dick again. Who are you to "educate" people when it's obvious that you don't know what you are doing. I've been rewiring guitars for 30 years and some people here have even more experience. Everyone has told you that it is a ground problem or something is wired backward. A guitar with humbuckers will not have the problem that you described even if it has poor shielding. You just won't own up to the fact that you made a mistake. I doubt that you will receive any more help because of your bad attitude and the fact that you like talking down to people. I guess you will have to go and tell your friend that you were too stupid to fix his guitar. I think I'll go and play one of my NON-Humming/Buzzing guitars.

                        Comment


                        • #13
                          There you go being a dick again. Who are you to "educate" people when it's obvious that you don't know what you are doing. I've been rewiring guitars for 30 years and some people here have even more experience.

                          Perhaps you can name some of those people with even more experience, so I can contact them directly and skip the ugliness that this thread is being turned into.

                          I've successfully shielded several guitars, and while I cannot claim 30 years of experience (I'm not even that old), I do have a clue about what I'm doing. This is the first time I've run into problems like this, and I was really hoping I'd get an answer from here. Instead, I get bombarded with ill-informed replies that seem to be based on common internet myths. I cannot possibly begin to fathom how someone with 30 years of experience can claim that the guitarist is grounding the guitar.

                          Everyone has told you that it is a ground problem or something is wired backward.

                          Can you stop the condescending for a moment and actually explain how this can be a grounding problem? You can start by refuting the explanation I gave in post #7.

                          A guitar with humbuckers will not have the problem that you described even if it has poor shielding.

                          Firstly, the neck pickup is a single coil, as I've mentioned already.

                          Secondly, there's more to a guitar than just the pickups. Wires, pots and other components also pick up noise if not properly shielded.

                          I doubt that you will receive any more help because of your bad attitude and the fact that you like talking down to people.

                          I've barely received any help at all.
                          It's a well-known fact that 100% of people who sell their Telecasters, die.

                          Comment


                          • #14
                            And how, pray tell, are you grounding the guitar? Are you standing barefoot on a metal plate? Or touching a water pipe, perhaps?

                            Your body acts as a shield, and the guitar is grounding you.

                            Your body, on account of being much larger than the wiring inside the guitar, picks up noise much better. When you're simply holding the guitar without touching any grounded metal parts, you simply radiate any noise you pick up right into the guitar's wiring. Hence the noise. As soon as you touch a grounded metal part on the guitar (such as the strings), you're grounded through said metal part, and the noise will disappear, as it's being shorted to ground. This is why shielding the guitar should help, as it'll provide a permanent, always-grounded layer of protection between the noise and the guitar's circuitry.

                            Here's a couple of fun experiments to try. Plug your guitar into your amp and turn it up. Don't touch any metal parts. Unless your guitar is well shielded, you should hear some noise. Now place your hand over any of the pickups, while still avoiding the strings. The noise should increase. Try moving your hand closer to, say, a computer monitor. The noise should increase even more. Now put the guitar away from your body (while it's still plugged in). The noise should decrease. This shows how your body is acting as a channel for noise. And unless there's another shield in place between you and the guitar, you'll have to ground yourself through the guitar to avoid bleeding that noise into the circuitry.

                            Also, when you touch the strings and the hum increases, it's a sign that the bridge (and hence the strings) isn't grounded. The reason is that you're inserting the noise into the strings, which in turn concentrate it right above the pickups (which are extremely effective antennae), rather than sending it to ground via the bridge.

                            Now, does anyone have any helpful suggestions?


                            How can we possibly help, when you apparently already know so much more than we?
                            "The Web puts all of the world's knowledge at our fingertips; unfortunately it's mixed with all of the world's bull****************."
                            -- Bob Parks

                            "A thing is not necessarily true because a man dies for it."
                            -- Oscar Wilde

                            "No man dies for what he knows to be true. Men die for what they want to be true, for what some terror in their hearts tells them is not true."
                            -- Oscar Wilde

                            "It is a trap of history to believe that eyewitnesses remember accurately what they have lived through."
                            -- Theodore White

                            Comment


                            • #15
                              I've barely received any help at all.


                              Actually, you have. You just don't recognize it as such.
                              "The Web puts all of the world's knowledge at our fingertips; unfortunately it's mixed with all of the world's bull****************."
                              -- Bob Parks

                              "A thing is not necessarily true because a man dies for it."
                              -- Oscar Wilde

                              "No man dies for what he knows to be true. Men die for what they want to be true, for what some terror in their hearts tells them is not true."
                              -- Oscar Wilde

                              "It is a trap of history to believe that eyewitnesses remember accurately what they have lived through."
                              -- Theodore White

                              Comment



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