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I have a problem with ground noise. I play at home through my recently bought MacBook M4/Focusrite Scarlett/Neuraldsp/monitor speakers. The sound is fantastic. But unfortunately, I experience a massive crackle on all guitars when I first touch the strings. It disappears as soon as I touch the strings or the bridge but comes back immediately. I‘ve never experienced this before and it's incredibly annoying. Only the speakers are connected to the power supply, all cables are professional. Anyone have any ideas? Thanks in advance!
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06-13-2025 05:40 AM
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First thing that comes to mind: the Apple laptop powerbricks I know can be used either as wall-warts or with an extension cable. Only in the latter case is the ground connected, and that's very apparent if I move my fingers across the laptop's housing. Scintillating when connected without ground, not otherwise.
Does the issue disappear when you use the Mac on battery?
Does it disappear when you playback via headphones or over the Mac's internal speakers (on battery and/or on mains power), with the speakers disconnected?
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Also try plugging everything in except the guitar. If there's no buzzing that is a clue that the guitar might be the problem. It's not definitive, but it's another data point.
Also try different cables. Just because your cables are "professional" doesn't mean they're perfect.
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Not with headphones!
It only appears if the speakers are connected (and they need 220V). Macbook on battery or plugged in didn‘t change a thing.
Pretty annoying: touching a string without any pressure and you hear „chk“. You intuitively look for a spark
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Some more things to check:
Originally Posted by Stefan Eff
Where are the headphones connected? On the Mac or on the interface?
If headphones on Mac and no buzz, what happens if headphones are connected through your Focusrite?
Does the signal to your speakers come from your Mac or your Focusrite? Try switching that around.
Do you have other powered speakers that you could hook up instead of the ones you are using? Does it still buzz?
Have you replaced the cable(s) between the Focusrite and the speakers?
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My remark about using a grounded PSU for the Mac probably also applies to the speakers.
The guitar itself is sound, strings in electric contact with the jack and all?
A "chk" sound, not the usual "whoom"? That does sound as if something fishy is going on!
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Headphones on both devices: no hiss. Originally Posted by dconeill
Speakers are connected to the Scarlett (not possible to connect to the Mac). Yes, I‘ve tried other speakers, same problem. And I‘ve also tried different cables between scarlett/speakers.
@RJVB: I‘m located in germany (grounded power cables are a must). Meanwhile I guess it‘s „bad electricity“ in our old house.
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I don't know if this is relevant, bu just in case...
I've read that hum which goes away when you touch the strings can be this. Your body is not grounded (until you touch the strings) and therefore acts as an antenna. The pickups can sense it which creates hum. It goes away when you ground your body by touching the strings (which are connected to ground via the ground wire to the bridge), or some grounded conductive object.
If this much is right, then it might change if you ground your body, or if you turn off any potential source of noise, e.g. certain kinds of lights or motors.
I think I would start by plugging a standard guitar cable into an unused jack which is connected to ground (on the outside of the jack) and simply holding the other end.
GP reviewed a product sold to address this problem. It amounted to a wire from the output jack ground to a small copper plate. You put the copper plate against your skin so that your body is grounded at all times.
Caveat: I'm not an expert and there could be a safety issue. It might be worth checking for unexpected voltages, just in case some device is broken and has its chassis going hot, meaning 115 volts AC.
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In that case you wouldn't really expect that "it" only occurs when the speakers are connected. Originally Posted by rpjazzguitar
But here's another experiment. Do you get "it" in the headphones when the speakers are connected in various ways, i.e.
- powered on and playing (softly so you hear the headphone signal)
- powered off but connected to the mains and the Focusrite
- only connected to the FR
(in the later case you could even check with the speaker power switch in the ON and in the OFF position.
You tried different speakers; do they use the same PSU, or something of the same design?
Someone more savvy about impedances etc. will have to ratify this, but I think that your powered speakers ought to be able to work with the headphone out signal if you find of make the proper adapter. Do you get the same problem then?
Finally, the way you describe the sound suggests you may want to check if the speaker cones aren't doing something unhealthy when producing it!
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That‘s what I meant with „dirty electricity“. I guess there is something in the electric circuit of my home which I receive like an antenna. There are products called „ground noise eliminators“, maybe this might be a solution? Originally Posted by rpjazzguitar
Last edited by Stefan Eff; 06-14-2025 at 03:42 AM.
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If it doesn't occur with headphones, it might be because the headphones are grounding his body. My headphones don't put a conductor against skin, but I suppose it's possible.
Easy enough to try it with headphones, but without touching the headphones to your body.
Otherwise, could be the speaker is generating the electrical field, I suppose. Leave it on, but listen through headphones?
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No, it disappears while using the headphones w/o speakers, so everything is just battery powered. Originally Posted by rpjazzguitar
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As an FYI, the wall wart power transformer that Apple supplies with its Macbooks is NOT grounded, the misleading ground pin notwithstanding. Appearances are misleading. There is no ground connection to the metal ground tab that resides within the wall wart. To electrically ground it you need to procure the $20 Apple extension cord that has a metal contact forming electrical ground with the round metal tab.
Edit: I see that you are running your M4 Mac off battery power. What active monitors do you have? I have a pair of Genelecs 8040Bs that came supplied with Schuko plugs. I suspect that your monitors are not grounded. Do you have a Schuko mains socket? Are you using some sort of multiway electrical adapter that defeats the Schuko grounding scheme? When you run your fingers over the chassis of your M4 Mac do you feel a "furry" tingle, a light vibratory feel? If you do that means that your entire system is not electrically grounded to the AC mains.
The Schuko wall mains has a metal strip that forms electrical ground with the 2-pin and 1-tab Schuko plug. If that mains strip is broken or if your Schuko plug does not have that metal 1-tab it becomes a 2-pin ungrounded plug. Check your Schuko plugs for that metal tab.Last edited by Jabberwocky; 06-16-2025 at 06:06 AM.
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Is your Scarlett's power supply connected to the mains with a non-Schuko 2-pin plug? Are your active speakers connected to the mains at the same time with non-Schuko 2-pin plugs? One of the components, Mac or Scarlett or one active speaker, needs to be electrically grounded. My Macbook Pro is powered by the wall wart with the Apple extension power cord and everything that I hook up to the Macbook is grounded by the Macbook. Originally Posted by Stefan Eff
Your old house may have a faulty ground. For your own safety (because I am sure you run other household appliances) get it checked and repaired by a qualified electrician.
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This is an example of a non-grounded 2-pin plug. If you are using this kind of plugs that is the source of your problem. Originally Posted by Stefan Eff
The wall mains Schuko socket, that you can see in your photo, has grounding strips on the top and bottom for Schuko plugs.
Your Scarlett and active monitors need to have 3-pin IEC power sockets. If they are 2-pin they are non-grounded. At least one is required to be 3-pin with a 3-pin grounded power cord before the entire is grounded.
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This is standard in germany. Originally Posted by Jabberwocky
Afaik every plug is made like this:
The green/yellow cable is ground.
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Exactly what I said (or meant to). Except that I never had to pay for the extension cable. Originally Posted by Jabberwocky
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Schuko 2-pin with metal ground tab and corresponding sockets. Does any one of your components use this plug?
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It is quite common for an imperfectly shielded guitar to be completely clean on a battery powered system and crackle or buzz on a grounded, powered system. The player is the source of the interfering voltage and, on battery, the whole system picks that up and floats at the interfering voltage so there is no spurious input to the system. When the system is grounded, as well as interference currents flowing to ground in the shields, the interference voltages at input and shield become unequal so there is an effective spurious input. Do you have a similar problem with a real grounded amp?
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Originally Posted by Jabberwocky
Schuko 2-pin with metal ground tab and corresponding sockets. Does any one of your components use this plug?I guess you are right, the cable from the monitors are causing the problem (since my guitars are correctly wired and don‘t do anything strange if plugged to an amp). Originally Posted by Jabberwocky
The problem might not be an easy fix since the monitors got those simple plugs:
Or is there any elegant solution to fix this? What about an DI box or this ground noise eliminator box?
And hey, thanks for all your help!
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The speaker obviously doesn't have a ground connection so its whole electronics, along with anything ungrounded connected to it, will probably be floating at around a half of the mains voltage. It will pass all safety tests because it can't deliver enough current to hurt but virtually no current is required to interfere with the guitar. A solution worth trying is to connect a wire to the ground pin of another mains plug and connect that to the shield of one of the input leads to the speaker.
I had a similar problem with an ungrounded power supply for charging a battery amp that caused hum because it floated the whole amp at 120V on 240V mains. The addition of a ground to the lead cured it.
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You could power your Macbook with the wall wart power supply but be aware that only the extension power cord sold as an accessory has a true ground pin. The factory supplied power supply as it comes out of the box is ungrounded-the ground pin is only for show. My Macbook power supply has a UK 3-prong adapter with a metal ground pin. I was flummoxed as to why I was getting a nasty "bite" whenever I touched the chassis of my Macbook as I thought it was grounded. I removed the 3-prong UK adapter and found that the ground pin had no electrical connection to the round metal ground tab within the power supply! It was misleading as heck! Why have a metal ground prong and not have an electrical connection to the interior ground tab? All that is required is a wire or metal tab. Apple!
The $20 extension power cord accessory does have this metal connection that makes contact with the round metal ground tab in the power supply. Ground your Macbook electrically and your guitar, Scarlett and active monitors connected to your Macbook will be grounded as well.
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This is the end of my accessory extension power cord. You can just make out the metal strip, one on each side, that makes contact with the round metal ground tab in the power supply in the background. The factory supplied adapter does not have these metal strips.
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Thanks, but I don‘t use my Macbook plugged in, only with battery.
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You have your own reasons that I won’t question. My power strip has switched outlets. Even if you do not charge up your Macbook and leave it plugged into the power supply, connected to your mains but not switched on your system is grounded by the ground pin. You need to pay about €20 for that official Apple extension power cord or €3 for a China knockoff. This is the simplest, direct and most cost effective solution. Originally Posted by Stefan Eff
If you know where the chassis ground screw is on your Presonus Eris 3.5 monitors you could run a ground wire from the chassis ground screw to the ground tab of a Schuko wall mains socket. Do that at your own risk.
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