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Jazz Bass picking up electronic signals?

M

maphiles96

Aug 31, 2023
13
6
#1
Hi all, first post here.

So I have an old Jazz bass that I really really like, however it sometimes produces a pretty unpleasant high pitched noise. It's worse in some spaces than it is in others, seems to depend on where I'm facing and goes away if I roll the tone or both pickups completely. The bass is (at least somewhat) shielded, though that didn't seem to make much of a difference and I don't have anything else in the signal chain.

Do any of you guys have and idea what could be causing this and how to fix it/minimize it without just always rolling off the tone?

Cheers
 
#3
Thanks for the reply.

I am using both pickups and a decent amount of noise goes away/gets more quiet (the bass has very little cycle hum for example) when turning both of the up, however the high pitched sound doesn't go away at all except when I bleed it off through the tone knob.

I've messed around with some audio analysis stuff and at least at home the sound appears to be in the range of 8 kHz and I'm pretty sure it's picking up some electrical signal from my pc.

I don't know if any of that information changes things, maybe the pickups just don't noise cancel properly and there's nothing I can do, but that'd still be good to know
 
#4
crguti said:
Jazz pickups are single coil. Single coils hum.


Use both pickups.
Click to expand...

The OP describes a “high pitched noise” that varies depending on position. That’s not hum.

@maphiles96 , with every passing year we surround ourselves with more and more electric and electronic doodads and gadgets. Our modern world contains many more sources of electrical interference than when your instrument was first designed. Try turning off and unplugging as many electrical things in your building as you can, starting with lights and large appliances. Shielding can definitely help, but may not cure it completely.
 
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#5
EMI Electro Magnetic Interference: As @ctmullins said "Shielding can definitely help [edit: for some types quite a lot], but may not cure it completely."

With passive basses ground loops are not quite as bad as described here, but the Fralin document is good: Understanding Guitar Grounding And Common Mistakes | Fralin Pickups

TIP: I shield the back of the pick guard around the PU on J & P basses (our old band room in an industrial factory was in a really badly affected EMI swamp). Use a strip of copper tape e.g. from the PU rout to one of the screw holes for the PG, when attached with the screw, it is then grounded.

If you make sure one of the screws for the control plate also is connected as above, you can skip the extra soldered wire as e.g. here:

Check every thing with a multi meter and especially in the control cavity ensure you did not create a short (e.g. near the cable socket).

If you can't get it under control to your satisfaction with grounded shielding (definitely try first, is cheap), then split or stacked coil J PUs is the next move (with cost & also tonal consequences).

Note: the copper tape for deterring snails/slugs has conductive adhesive (important!) and costs a fraction compared to the "guitar/bass shielding tape"... it is the same stuff, sometimes better/thicker.
 
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#9
ClusterFlux said:
You can also try an Electro Harmonix Hum Debugger.
Click to expand...
I use a Hum Debugger and it works great. I have plenty of vintage basses and I'm surrounded by all sorts of noise sources including huge water pumps, industrial lighting, and broadcast towers. The Hum debugger takes almost all of everything away, with the exception of some of the broadcast tower noise - it takes away most, but sometimes when I face a certain way I can hear a little bleed through . That's when I discovered that it was actually a cable. Replaced the cable and voila! All the noise gone.

So, moral of the story? Try a hum debugger and check your cables.
 
#11
maphiles96 said:
Hi all, first post here.

So I have an old Jazz bass that I really really like, however it sometimes produces a pretty unpleasant high pitched noise. It's worse in some spaces than it is in others, seems to depend on where I'm facing and goes away if I roll the tone or both pickups completely. The bass is (at least somewhat) shielded, though that didn't seem to make much of a difference and I don't have anything else in the signal chain.

Do any of you guys have and idea what could be causing this and how to fix it/minimize it without just always rolling off the tone?

Cheers
Click to expand...
Can post a soundbite?
 
#13
Thanks for all the tips! I will check out the video about shielding and try to improve the one in my bass (it's pretty lackluster from what I understand)
I'll also check my cables and see if turning off stuff improves the issue. It's currently the worst when I'm in my rehearsal space, so I'll mess around there a bit, grab some recordings of the sound and get back to you guys!

Thanks again for being so helpful :)
 
#15
Here's the promised sound bite! (I hope this is the proper way to share sound, if not pls let me know)

This is recorded with high gain and I'm turning roughly 90° back and forth which makes the noise increase and decrease. You should be able to hear me turn the pickups on and off, in the first two sets of turns it's a single pickup each with my hands on the strings and off the strings respectively. The third set has both pickups on.

As you can probably hear it's far more quiet with both pickups turned up and there's also a difference whether my hand touches the strings or not. Having one pickup turned down makes the issue far worse.

Other cables also produce the sound and I get it from other amps too, also everything I could turn off in the room was turned off.
I also noticed that my pickups were out of phase before which is fixed now (and in the recording) which is probably why it's so much better with both pickups on. Before it was just as loud with both as with one singled.
 
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#16
That sounds like computer noise to me, but could also be a switching power supply or wallwart.

How *I* would narrow it down:
1. Get some way to run on batteries. Fender mustang micro, NUX mighty, whatever...
2. Confirm it's still happening in that configuration.
3. Turn off the house main breaker. (Learn from my mistake, tell everyone in the house you're gonna do this, FIRST. :roflmao: )
4. Sound gone? OK, something in your house. Turn off all the circuit breakers, turn ON main breaker, turn on circuits one by one. (helps here to have assistance.) When the noise comes back, that's the circuit it's on--narrow it down from there.
5. DIDN'T go away? It's not your stuff. Neighbor's grow lights, bad transformer on power pole, nearby neon sign, nearby solar panels? Can maybe use a cheap battery AM radio to track it down.

Can follow the info Ham Radio users have posted on this as well. See the ARRL site links that come up googling "Track down RFI interference." If you have a local ham you know, they might be able to actually help track it down--this is the kind of stuff they get excited about.
 
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#17
I'll try and go through these steps, maybe I have some loud or faulty equipment around somewhere and finding it solves it.

However I've also had this happen at gig venues (which is where it becomes a slight problem). so if there's something else I can change in case I don't have faulty equipment going ham, that'd be nice.

I'm currently still waiting on the supplies to improve the shielding, maybe that'll just do the trick
 
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#18
Okay, time for a progress report!

I've now shielded the bass completely with shielding paint in the cavities and foil on the back of the pickguard. I've also redone (and simplified) a decent amount of the old wiring and and the results are promising... mostly.

With both pickups turned up the bass is nice and quiet, and the same applies if I solo the neck pickup. However while the bridge pickup sure is less noisy, it's also far from quiet. The question is now is this down to the pickguard (and it's shielding) not extending to the bridge or did I mess up somehow?
 
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#19
Sounds like this is helping.

If you are measuring no more than a couple of ohms resistance between your shielding in the bridge rout & e.g. to the bridge or negative pole on the jack, your shielding/grounding should be good. [I find copper tape functions better than shielding paint, but you may have a good one]. With a multi meter make sure *all* of your shielding areas have a good ground connection (including the back of the pick guard... otherwise it will be an antenna ;) ).

Aside from eliminating the source(s) of the EMI, it is difficult to fully stomp it out completely, especially in a J PU bridge position without going the stacked/split coil route.

=> while the bridge pickup sure is less noisy, it's also far from quiet

You could try the extreme method which may help a bit more (but probably not stomp it out completely):

If your Bridge PU casing allows it space wise you could try shielding the inside of the PU case with copper tape (or find a nickle aka german silver case for it). Remember it needs to be grounded to function as an EMI shield. This should also ground the bridge pole pieces at the same time (if they do not have a protective lacquered finish on them).

- Be really careful not to allow the tape shielding to contact the PU solder point. PU silence will be the result.

- *IF* one of your pole pieces should be shorted to the coil wire, the PU will also become silent (rare, but I have one which has the issue and had to remove the pole piece grounding from that one particular pole piece .... I have never done the case shielding above, but do normally ground the pole pieces at the bottom of the non new-fangled PBC types - where they should normally be grounded per default - stops clicks/buzz when you touch them).

Tip: When soldering a wire to copper tape shielding on plastic parts, do it before you attach the tape to the plastic part....
 
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#20
Since yesterday I've played around with a couple of things. First it seems one of the connections of the neck pickup was slightly dodgy and maybe shorting to ground or something, cause the pickup was way more muffled than it used to be. After redoing the connections there its sound came back, but so did some of the noise. It's still more quiet than the bridge one, but not by much.

If you are measuring no more than a couple of ohms resistance between your shielding in the bridge rout & e.g. to the bridge or negative pole on the jack, your shielding/grounding should be good. [I find copper tape functions better than shielding paint, but you may have a good one]. With a multi meter make sure *all* of your shielding areas have a good ground connection (including the back of the pick guard... otherwise it will be an antenna ;) ).
Click to expand...

I did line the neck cavity with copper tape and it didn't really change much, but it's now measuring ~0.4 Ohms to ground, and so is the pickguard. The bridge cavity measures about 150 ohms (only the tip of the multimeter) or around 70 Ohms with the probe laid flat, though that one currently only has paint in it.
I heard that shielding the pickup covers supposedly cuts some high end, which would be somewhat annoying, but maybe it's worth a shot anyways.

My polepieces are not grounded, though I'm planning on doing that in the near future as well.

It might also be worth mentioning that part of the noise is originally had went away when I touched metal, though that part seems to has gone completely now.
I'll be back in my rehearsal space today and will grab some more sound bites to compare

Thanks again for all the help
 
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