Why does a JMJ buzz but not a P bass?

[socknroll1]

Basically the title.

True single coils have 60 cycle hum. A bass with a split coil pick up, like a Precision bass or this JMJ Mustang bass, does not have 60 cycle hum. But this JMJ hums in a different way. In some venues and practice spaces, it's bad. In others, it's completely fine. In the places where it's bad, it goes away a little when I touch the strings, and much more when I touch a tuning peg.

I just got home from 2 shops where 2 very knowledgeable owners each confirmed that the bass is grounded correctly. Of course, they had good power in their shops, and it did not hum much in either. I know a lot of people here have had good success with copper shielding. However, interestingly, each shop owner said that they could do copper shielding for me, to the tune of a few hundred dollars, but they did not feel comfortable saying it would help. They are both skeptics about that.

I've searched and found a few threads with noisy JMJs, but I didn't get a clear answer to my q.

I can't remember ever having a split-coil bass that hummed like this. It's a great bass, I'm just stumped - what makes this different than your average P bass? What makes this bass noisy?

 

[BGroovy]

I shield every one of my basses because I want them as quiet as possible. Buy a roll of tape and do it yourself for $30. It doesn't have to be pretty, just test the connectivity. No one will see it and it's removable should a future owner want to redo it. Always worth doing IMO.

 

[jd56hawk]

I'm in no way a handyman, but shielding a bass is easier than filing sharp fret edges, installing new pickups, changing hardware, etc, not to mention you can buy a roll for $10.
If I can do it, anyone can.

 

[hooky_marr]

1. If everything’s grounded properly and you have done basic troubleshooting (try to replicate the problem, try in different locations, A/B test to rule out cables, amps or pedals), then what you have is plain old RF interference which can affect the wiring in the control cavity.
2. Asking hundreds of dollars to do copper shielding is…a lot. You can get a roll of copper foil tape with conductive adhesive off Amazon or at a better hardware store, and do it yourself in an afternoon.
3. Since everything electronic is attached to your pickguard it’s pretty easy to remove, line the cavity, and leave a tab to complete the Faraday cage with the foil on the back of the pickguard. (If there isn’t any, remove the electronics and add some.) All you might need to do after is attach a grounding wire from the foil to your output ground. Test for continuity with a meter!

 

[T McClure]

1. If everything’s grounded properly and you have done basic troubleshooting (try to replicate the problem, try in different locations, A/B test to rule out cables, amps or pedals), then what you have is plain old RF interference which can affect the wiring in the control cavity.

This is it. I've had both P basses and a JMJ that had hum, and some copper shielding fixed it.

I've done it myself with the copper tape, but my local shop will do it for something like ~$40.

 

[PotsdamBass8]

I had an American Precision Special that had the pickup wired wrong. I don’t know enough about wiring to explain how it was wired, but basically the two halves were connected without the polarity being reversed. They sounded basically the same but had a 60 cycle hum. I also took it to one tech who could not figure out the problem and tried to convince me that P pickups aren’t actually hum canceling. I took it upon myself to open it up and after trying a couple different configs based on info I found online, was able to get it wired the correct humcanceling way.

Long story I know, but I felt it was important to properly explain what happened because it’s totally possible that this is the case here but it’s such an easy to miss thing.

 

[Bodeeni]

Sheilding definetely helps but I have a few humbucking pickups that still are prone to some RF noise. It is the pickup itself. I can switch it out in the same bass to a similar pickup with no hum. Seem to be the hotter ones, but not all.

 

[MechaSparky]

Do it yourself - it's easy and fun if you just go slow. You could try snap-on RF chokes on the feedline at the bass, and at the amp. When you figure it out be sure to come back and tell everybody I was right.

 

[LetItGrowTone]

I dimly remember that some Mustang pickups are *not* RWRP, but I could be wrong. Sorry if I'm wrong.
I would ask in the Mustang Club (or search those 322 pages).

 

[Bass4ThePublic]

Shielding works, do does anti static spray. Fwiw, I'd do both

 

[2F/2F]

Make sure that one coil is RW/RP from the other. This can easily be messed up in the factory.

Definitely don't pay anyone to shield your bass. That's a waste of money. If you really feel that shielding is necessary, it's very easy to do yourself.

I have been playing since 1988, basses with all types of pickups, from single coil to humbucking, and active and passive. I've never once shielded a bass, and never once had problematic buzz that wasn't caused by a wiring fault.

 

[CaperBass]

Make sure your bridge grounding wire is making good contact with the bridge and to the electronics.

 

[KevInDaBassment]

...However, interestingly, each shop owner said that they could do copper shielding for me, to the tune of a few hundred dollars, but they did not feel comfortable saying it would help. They are both skeptics about that.

Everyone is correct in saying that's crazy to charge that much for copper shielding something...I'm blown away that they are both "Skeptics" about it. Are they skeptical of it working on this bass or just its efficacy overall? I can say without a doubt, done correctly it's a fantastic way to really knock out a ton of noise. I was in an apartment not long ago and I would get all sorts of noise from my basses. I shielded my jazz bass well and it was whisper quiet in there compared to before.

 

[socknroll1]

Buy a roll of tape and do it yourself for $30.

Could you share a link(s) to the right product? Searching "copper foil tape" on the big hardware sites did not yield good results.

3. Since everything electronic is attached to your pickguard it’s pretty easy to remove, line the cavity, and leave a tab to complete the Faraday cage with the foil on the back of the pickguard. (If there isn’t any, remove the electronics and add some.) All you might need to do after is attach a grounding wire from the foil to your output ground. Test for continuity with a meter!

I appreciate this, but I bolded the parts I don't know how to do/am afraid I am going to mess up. I have been doing setups for 25 years but I really know nothing about electronics. Is it worth doing if I just apply tape and do nothing else?

Do it yourself - it's easy and fun if you just go slow. You could try snap-on RF chokes on the feedline at the bass, and at the amp. When you figure it out be sure to come back and tell everybody I was right.

No idea what the bolded words mean, sorry.

Make sure that one coil is RW/RP from the other.

Respectfully, how?

Make sure your bridge grounding wire is making good contact with the bridge and to the electronics.

The shop owners both confirmed this.

Are they skeptical of it working on this bass or just its efficacy overall?

They are skeptical of it working overall. One said, it can cause more problems than it solves.

Thank you all.

 

[UntitledProject]

They are skeptical of it working overall. One said, it can cause more problems than it solves.

Frankly, if a tech said this, you should not be taking anything to that tech. Proper shielding cannot introduce any problems. Improper shielding can. If they have had situations where shielding has caused problems then they are not competent to apply shielding.

 

[GrooveCaptain]

I'll add that I shield every bass I own too. Even if they have the tiniest hum, that knocks it out. It's not hard at all to do, just time consuming. Find a YouTube video on it and take your time. There's no way it should cost 200.
Also, make sure you get a roll that's 'adhesive conductive'. Something like this one...

Limited-time deal: LOVIMAG Copper Tape, Copper Foil Tape (2inch X 33 FT) Metal Conductive Adhesive for Slugs Guitar and EMI Shielding, Crafts, Electrical Repairs, Grounding https://a.co/d/03qgU6Sx

 

[BGroovy]

I'll add that I shield every bass I own too. Even if they have the tiniest hum, that knocks it out. It's not hard at all to do, just time consuming. Find a YouTube video on it and take your time. There's no way it should cost 200.
Also, make sure you get a roll that's 'adhesive conductive'. Something like this one...

Limited-time deal: LOVIMAG Copper Tape, Copper Foil Tape (2inch X 33 FT) Metal Conductive Adhesive for Slugs Guitar and EMI Shielding, Crafts, Electrical Repairs, Grounding https://a.co/d/03qgU6Sx

This is the exact tape I've been using last few years. I've gone through 2 66ft rolls shielding > 40 basses

 

[Dark Horse]

https://a.co/d/00AGtQN5

$10

 

[KevInDaBassment]

Frankly, if a tech said this, you should not be taking anything to that tech. Proper shielding cannot introduce any problems. Improper shielding can. If they have had situations where shielding has caused problems then they are not competent to apply shielding.

This x100000 ^

I know you stated you've got trust in them, OP....but their statement about shielding is like saying adding insulation to your home makes your A/C perform worse, or introduces more problems than it solves. There's a point of diminishing returns, but you're not hurting anything by adding properly-installed shielding. Sounds more like they don't want to fool with installing it correctly to me

 

[Dark Horse]

They are skeptical of it working overall. One said, it can cause more problems than it solves.

Thank you all.

In 48 years of playing, and 32 years of building/repairing guitars, I’ve never once seen shielding CAUSE a problem. Ever.

I have, however, seen it SOLVE a lot of noise issues.

Just my experience.