Constant hum through audio interface?

So I'm using:

Scarlett 4i4 (3rd gen), only a week old.Logic Pro X

Mic pick up in my acoustic guitar.

When I plug in my acoustic guitar, there is a constant signal being picked up in Logic which, when I turn my speakers up, is a very prominent hum noise.

I literally cannot get it to go away.

Is this a damaged audio interface?


1. I'm aware this may be something called a ground loop?

2. Sometimes, when I touch metal, such as my MacBook, or the casing of my interface, the hum stops.

4 Answers

  • 5 months ago
    Favourite answer

    That sounds like a fault in the screening of the guitar cable or pickup.

    When you touch the computer you are grounding yourself and reducing the hum pickup.

    It is not a "ground loop; that is from two or more different electrical paths to ground. Also, that would not be stopped by an additional ground.

    And if it's the same on more than one input on the scarlett, it's not a fault in that.

    My first thoughts are try a different guitar lead, and get the guitar checked out.

    Especially if it's a DIY pickup addition or an ebay item, it may need a better quality one.

    And / or additional grounding adding adding in the guitar if it's a metal string one.

    [Professional electronics designer and hobbyist-level guitar repairer].

  • Tony B
    Lv 4
    5 months ago

    I agree with Robert J - it sounds like a problem with the guitar/pickup.

    I have an old guitar with an under-saddle piezo and it hums whatever it's plugged into.

  • 5 months ago

    All your devices must be properly grounded together to avoid ham sound .

  • 5 months ago

    Hum is usually a sign of unshielded pickups or a short.

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