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I have a humming that comes through when I am plugged in on any of my instruments, it seems. I am plugged into a workstation and not to an amp. I do not think anything problem with the instrument as I have tested it on several guitars including a brand new Taylor 314. The humming does stop when I touch the ends of the instrument cable, but it does not stop when I touch the strings. Any ideas? Everything that I have seen indicates that it should also stop when I touch the strings.

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  • Thanks! I use a workstation, so I don't actually use a computer at all. I do have it on a wooden platform - would changing how I store it help? I do know that there is some weird wiring in our house. I guess I could use a noise gate on my effects pedal...
    – Chi Wright
    Oct 10, 2020 at 23:27

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This is a grounding issue. Guitar connections generally have high impedance, which makes them very susceptible to capacitive interference. To avoid this, devices should be shielded: all circuit elements should be surrounded by a conductive foil or cage, which needs to be connected to ground or a common reference. Guitar manufacturers, alas, routinely cheap up on this and don't properly shield the interior, but they've found that there's a trick to achieve a similar shielding: just connecting the strings to ground means as soon as you touch them, you will be grounded too, and therefore your belly acts as shielding. Thus all the advice for electric guitars to touch the strings, and the same thing works of course also when you ground yourself directly from the cable.

But make no mistake, this is a horrible hack and can actually be dangerous if something goes wrong in the amp and ground gets connected to a live wire. Or the other way around if you touch something else at live potential whilst holding the guitar. There have been a lot of accidents of this kind in the 60s and 70s, typically the story was a guitarist touching a microphone and getting a full-on shock through their head. Nowadays devices tend to be built better and there are RCCBs that immediately trip the power if this happens, but it's still a pretty bad practice.

Whether for this reason or others, electrified acoustic guitars normally don't ground the strings, that's why touching them has no effect on your Taylor. Too bad that they did apparently not do a great job with the shielding, which would make body-grounding unnecessary. Unfortunately it's also difficult to retrofic acoustic guitars with internal shielding – you could try wrapping the electronic parts in tin foil and connecting that to ground, but I wouldn't expect that to work very well. I suppose you'll be reluctant to wrap the outside of the guitar, but that probably would do the trick...

Seeing as this happens with all your instruments, it is evident that your room has a particularly big problem with interference. An electrician may be able to diagnose the issue.

If all else fails... the good news is that 50/60 Hz hum is actually quite easy to remove after the fact, unlike hiss noise or power-supply brizzle. In a recording, you may use any denoiser plugin or even just a notch or comb filter in an EQ plugin. There are also effects pedals available that do this in a live setting.

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  • "can actually be dangerous if something goes wrong in the amp and ground gets connected to a live wire." Actually, if that happens, the current will flow straight in the earth and not in the body. All frames of electrical object are grounded for this purpose, to protect the user which can touch the frame in case of a short. Of course this is valid only if it's properly earthed ;).
    – Tom
    Oct 10, 2020 at 7:52
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    As so few countries seem to have compulsory earthing, I'd start from the other end. Make sure the computer is earthed to start with. Also, when working near a computer screen, make sure that's not the source of your interference - move away from it or switch it off entirely to check.
    – Tetsujin
    Oct 10, 2020 at 9:36
  • @Tom sure, that's how it should be. Unfortunately though, if everything is grounded and unbalanced connections are used, the resulting ground loops cause their own hum issue. The correct measure is to galvanically decouple the audio connections, typically with a DI box; but many engineers (-for the lack of a better word) make use of the cheaper hack: just interrupting the ground connection at the power plug. That's probably the real reason behind those accidents I mentioned, and the guitar manufacturers deserve only a smaller part of the blame, but that doesn't mean it's good practice. Oct 10, 2020 at 14:38
  • @Tom - the problems in the past where guitarists in particular have been electrocuted were because the earth wire inside the plug became detached. No problems until it touched the live pin inside the plug. Also, no earth for any electricity to flow safely through to. Then, the chassis of the attached amp. became live. Still no problem - it wouldn't be detectable until someone - the guitarist, who was then connected directly to live - touched earth, often through a mic, which was connected to earth. Circuit complete, muscles spasm so the mic can't be thrown off, electricity through body, ...
    – Tim
    Oct 11, 2020 at 10:46
  • @Tom... at worst, death. Not so prevalent these days, with RCDs, etc., and plugs that are sealed.
    – Tim
    Oct 11, 2020 at 10:47

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