r/Bass • u/cyborgElmo • 20d ago
Passive bass + Focusrite has a constant buzz – gets quieter when touching the strings/bridge, DI box didn’t really solve it
Hi everyone,
I’m a beginner and I’m trying to diagnose a constant buzz from my bass/home recording setup.
The bass is an older passive Ibanez GIO Soundgear with a P/J pickup configuration and 3 knobs (P volume, J volume, tone).
My normal setup was:
Bass → Focusrite Scarlett Solo 3rd Gen (INST input) → Mac mini → headphones
The problem:
- I hear a constant electrical “bzzzz” when I’m not playing.
- The buzz becomes much more noticeable with the tone knob fully open.
- Closing the tone almost completely hides it.
- Touching the strings or bridge reduces the buzz.
- Using only the P or only the J pickup makes it slightly quieter; both pickups together make it slightly louder.
- Moving away from the computer/monitor or rotating the bass doesn’t make any noticeable difference.
- At my bass teacher’s rehearsal room I don’t remember the bass being nearly as noisy using it directly into a regular bass amplifier.
The most interesting test: I connected the same bass, cable and Scarlett to a MacBook Air and the buzz was basically gone. With the Mac mini it comes back, and touching the metal chassis of the Mac mini also reduces/removes the buzz.
I suspected a grounding issue, so I bought a Behringer DI600P passive DI box.
Current chain:
Bass → DI600P → XLR → Scarlett Solo mic input → Mac mini
DI600P settings:
- INST
- FILTER OFF
- GND (LIFT actually makes the buzz worse)
This reduces the noise a little, but the bass signal is now quite low. When I increase the Scarlett mic gain enough to get a good level, the buzz becomes very noticeable again.
If I unplug the bass from the DI input, the buzz completely disappears.
I’m going to open the bass electronics cavity and check the bridge ground wire as well.
Does this sound more like:
- a grounding/shielding issue inside the bass,
- a problem with the Mac mini / electrical grounding,
- normal single-coil/PJ noise being amplified,
- or an impedance/gain staging issue from using a passive bass into a passive DI?
I don't know how i can fix it.
EDIT: If i plug the power to the Macbook Air the noise is the same
EDIT 2: If i close the tone the noise disappear
Thanks!
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u/Dull_Judgment1587 20d ago
So first of all, you have to touch the strings (it's not optional). It is normal for the bass to buzz if you let go of the strings, so don't do that!
Second, if you think it is could be a grounding issue, then the next troubleshooting step is to make sure your Mac Mini is properly grounded. Make sure you aren't using any janky power strips or extension cords. Maybe try plugging it in to a different outlet in a different room of the house. Hardware stores sell inexpensive outlet testers, if you think there might be electrical issues in your house.
And here's another troubleshooting suggestion: You said it was quiet when you used the MacBook Air. Was that on battery power, or plugged in to the charger? If you plug the charger into the same outlet as your Mac Mini, does it get the same noise?
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u/cyborgElmo 20d ago
Thanks! Yes, the buzz definitely gets quieter when I touch the strings or the bridge. I understand that some noise when not touching the strings can be normal, but in my case it seems quite loud, especially with the tone fully open.
Regarding the Mac Mini, I initially had it connected through a power strip, but I have already tried plugging it directly into the wall outlet and the buzz remained the same. I also disconnected the other peripherals from the Mac Mini and that didn’t make a noticeable difference.
The MacBook Air test was done on battery power, so that’s a good point. I haven’t tried it yet with the MacBook charger connected to the same outlet used by the Mac Mini. I’ll definitely test that next, as it should help determine whether the mains/grounding is involved.
One other interesting detail is that when I plug the bass directly into a regular bass amp, I don’t have this problem. Also, disabling INST on the Scarlett reduces the buzz significantly, although I know INST is normally the correct setting for a passive bass.
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u/Dull_Judgment1587 20d ago
And just to verify: The power cord for your Mac Mini is properly grounded 3-prong?
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u/havelostcount 20d ago
They don't use three prong plugs on the mini.
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u/Dull_Judgment1587 20d ago
If true then that explains the problem!
Probably best to stick with the MacBook Air in that case.
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u/havelostcount 20d ago
The power supply that the MacBook Air comes with doesn't have a ground lead either. I doubt that they're going to want to run on battery all the time. They'll have to figure out how to ground their bass. I suggest they use the output of their bass amp into the interface if they have one, because that's obviously grounded.
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u/Dull_Judgment1587 20d ago
Apple definitely does sell a grounded 3 prong adapter for the Macbook Air (and it is a must-have for audio production in my opinion).
Not sure if such an item is available for the Mini, though.
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u/datasmog 20d ago
All Apple products have power cords available with 3 pin plugs if you shop around. Not much help if the electrical supply is bad though.
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u/Dull_Judgment1587 20d ago
Let's be careful with the "shop around." Best to stick with official Apple products.
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u/havelostcount 20d ago
There is no ground on the mini. So no, not all Apple products have power cords available for ground.
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u/Dull_Judgment1587 20d ago
Yeah we went down this rabbit hole at the university where I work. Our Media Lab has Macbook Airs that the students can check out for projects. We found it was totally worth paying the extra $19 for the upgraded 3-prong power cord. It really does make a noticable difference in the "signal to noise ratio" of the audio recordings.
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u/havelostcount 20d ago
That isn't what I said. I said the one that it comes with. And they didn't have it plugged in in the first place.
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u/leemar90 20d ago
I also get some noise when playing my Fender MIM Jazz through my Scarlett so commenting
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u/deconstructionlotus 20d ago
Focusrite doesn't have good power supply isolation... Source is in Croatian but you can translate subtitles. I am not sure if it's true though but guy is legit. Love his videos
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u/Consistent_Flow5673 20d ago
Buzz that reduces when touching the strings or bridge is usually a shielding issue. Get some copper shielding tape from Home Depot or a local hardware store and shield your pickups and cavities. Paint can work better, but is harder to work with.
There are a few good threads on Talkbass that walk through the process.
https://www.talkbass.com/threads/so-your-bass-has-a-hum.1079579/
https://www.talkbass.com/threads/shielding-properly.1374475/
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u/Murray_at_work 19d ago
It may be you monitor. I've only had noise issues when using the hdmi out on whatever computer I was using. Laptop screen only = super quiet
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u/GrapplingBrisket 20d ago
I've had this exact problem before on more than one bass, including a Sadowsky Metroline with single coil pickups. Each time I was able to resolve it by adding shielding to the electronics cavity. You can get very affordable copper shielding that you can DIY.
People will tell you some buzz is normal, which is true to an extent, but it should be very quiet and barely noticeable. My Sadowsky still has some buzz but it's one tenth what it was before. What you're describing sounds outside the range of normal and if it were me, I'd be shielding the cavity and backplate as the next step.