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P bass noise - XLR only

B

basyngwie

Feb 12, 2023
25
18
#1
I have an issue with one of my basses (Fender Japan Heritage 60's P bass). It will make a considerable buzz noise when going through an XLR. It's drastically reduced by turning down the treble on the amp or the tone on the bass. I've tried different cables and the issue appears both when using the XLR from my amp (Ampeg PF 350) and when using a stompbox with XLR out. The noise isn't picked up on recordings (recording through a Behringer UMC202HD) but I fear it could be a problem in a live situation (this I haven't had the opportunity to try).

The problem seems to be the bass as I can't hear it when using my Sire P5. As I have no problems when running through my cab (well, just some ground noise when not touching the strings) or plugging the 1/4 jack direct to the Behringer for recording, is it possible my Fender bass has some wiring or shielding problems that gets enhanced through the XLR? Where would I start to look?
 
#3
Sometimes when you run a line between two devices plugged into different wall outlets, you get this thing called a ground loop. A ground lift switch might help; I've also dealt with it by using an extension cord to power the amp from the same circuit as the mixer.
Worth a shot, anyway. If that's not the culprit this time, it will be sooner or later.
 
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#5
CatOnTheBass said:
Have you tried using a different XLR cable? That would be my first troubleshooting step.

(Or just use 1/4" instead of XLR, which, if I am understanding correctly, completely solves the problem?)
Click to expand...
Do you mean at a gig, just plug the 1/4" to the PA mixer? Haven't thought about that but that might work. The benefit of the XLR is of course to be able to have both the amp and the PA (same with recordings) but I guess some sort of 1/4" splitter would allow something similar?

edit: Since my Boss tuner has two outputs (and buffer) I will have to try this tonight. I suppose I will lose the ability to tune in silence though :/
 
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#6
I have established that the problem is connected noisy surroundings. If I sit infront of a computer etc. it will buzz and not otherwise. But I can't for my life get the same buzzing without the XLR. That's what's puzzling me.
 
#7
This is puzzling and it might take a few more rounds of Q and A to get to the bottom.
Sorry I don't gave anything specific for the issue you are having. However, if you need to do a ground lift but don't have that switch either at your end of the XLR or the device you plug into. (Many mixers and interfaces include ground lift switches) then you can make one fairly easily.

The ground lift is accomplished by disconnecting pin one in an XLR connector. If you have a choice, do this at your end of the cable, but doing it at the other end will work to lift the ground as well. I always had a couple of short XLR cables in my stash with pin one disconnected. If you do this, be sure to tag them somehow so you know they are Ground Lift adaptors.

Also XLR D.I. outputs come in two flavors. Mic level and line level. They must match levels at both ends. Mixers and other interfaces often provide for both levels either by a mic/line switch, or a very wide range input gain setting on the mic/line input of the mixer ot interface. Getting these wrong can add a lot of noise.

Also be sure you have proper interfacing when going from XLR to 1/4" or vice versa. If you aren't sure about that, let us know. There are easy solutions, but it depends on the particulars of your setup.
 
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#8
I’m still not exactly sure I understand where the XLR fits in your signal path and why exactly you’re using an XLR with a bass. So forgive me if my suggestion doesn’t track.

To help pin this down a bit more, is this a new buzzing? Did the P Bass + this signal path work without the noise until one day there was noise? Or has it always been noisy like this? If it is a new noise, did you do anything new to your bass, gear, or setup within a few days before the noise started? If this is a new new noise, and absolutely nothing else changed, considering you’ve tried different cables, could any of the wires or solder joints in the bass possibly come loose? Possibly something that should be attached to ground but isn’t anymore, or just a bad connection?

The fact that it’s NOT picked up on the recording but you can hear it (I assume through your amp?) makes me think the issue isn’t the bass or the cable or the gear, but the amp itself. There’s a potential ground issue in your amp’s power cable, or something in the circuitry inside shook loose and causing a ground issue that’s only noticeable when the signal paths involve balanced cables. Or, like was mentioned earlier, the amp and the recording equipment are plugged into different circuits causing a ground loop. Try swapping out the amp’s power cable and make sure the amp and every thing else your audio is running through are all on the same circuit. (Although it’s still weird that you’d only hear it on one bass and not the other.) Also make sure nothing else that isn’t part of the audio gear is plugged into that same circuit, especially any lighting gear, but also TVs or random things.
 
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#12
Are you saying the signal path is bass guitar to amp with standard 1/4" instrument cable, then amp to UMC202HD with XLR cable, and you're hearing unwanted noise through the amp's speaker but not through the UMC202HD?

And if you disconnect the XLR from the amp the noise disappears?
 
#13
nnnnnn said:
Are you saying the signal path is bass guitar to amp with standard 1/4" instrument cable, then amp to UMC202HD with XLR cable, and you're hearing unwanted noise through the amp's speaker but not through the UMC202HD?

And if you disconnect the XLR from the amp the noise disappears?
Click to expand...
That's the signal path (or bass to Di driver to UMC202HD in that manner) but the noise isn't coming from the speaker, it's just in the monitors and headphones connected to the UMC202HD.
 
#15
Well I don't know if this is good news or just more puzzling but when I plugged in to try some of your tips (remove lights etc) the noise was gone. Couldn't make it buzz/hum if I my life depended on it. Same amp, light, cables. I don't know how to handle this but I guess I should be glad?

One of you asked if the noise was new and I honestly can't tell if it has always bin there. I haven't DI:ed this bass for a while but when I sat down to record my reaction was more like "oh right, this noise" so I guess it wasn't all new to me. It could be something that's coming and going. But it was probably louder than before since I felt I had to do something about it.

Edit: Come to think of it I’ve actually moved my “studio” to another room, maybe a month ago. Maybe that’s why I’ve never experienced it in this way before.
 
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#16
So you can hear the noise but it's not picked up on recordings?

Just to get this out of the way: Are we talking about noise that disappears when you touch the strings (or the bridge)?

Also, is your computer grounded? Most consumer level laptops aren't and they WILL be noisy for recording unless they are grounded through other gear.

As for pickup up noise when sitting in front of a computer... Most basses will do that (to a certain degree) but the Fender shouldn't pick up a lot more noise that a P5. It could be poorly shielded, or it could be an issue with a ground ground connection somewhere.
 
#18
Deleted member 271037 said:
Just to get this out of the way: Are we talking about noise that disappears when you touch the strings (or the bridge)?

Also, is your computer grounded? Most consumer level laptops aren't and they WILL be noisy for recording unless they are grounded through other gear.
Click to expand...
Touching the strings didn’t affect it. My computer is an old MacBook Pro. I assume it’s grounded when the MagSafe is connected since the electricity outlets in the room are.
 
#19
basyngwie said:
Touching the strings didn’t affect it. My computer is an old MacBook Pro. I assume it’s grounded when the MagSafe is connected since the electricity outlets in the room are.
Click to expand...

Do you notice a difference, running your laptop on battery power vs. connected to the charger?

Does your MagSafe have a 2 prong or a 3 prong AC plug? If it's a 2 prong plug then it's not grounded. ;) The 3-prong "Power Adapter Extension Cable" costs an extra $19 and is money well spent if you use your Macbook for audio production, to be grounded.

Or, always run on battery power, which is not ideal. Or, try a DI with a 'ground lift' switch. Or, use an unbalanced 1/4" guitar cable instead of XLR.
 
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