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Fender jazz bass mim, 3rd knob hums like mad

Aaron Crawford

Aaron Crawford

Aug 6, 2019
7
4
#1
So I bought a second hand but nearly new bass guitar last year. I've noticed as lot of hum from it but at first put it off as a part of the design. Im not sure when it happened but now if I engage the 3rd knob at all it gets bad static that wanes a bit if my hands are on the strings.

I assumed it was a pickup issue so I bought some 60's fender jazz pickups and installed them... The new pickups sound great! But now the buzzing is even worse.... I think the new more sensitive pickups are just catching it more...

What should I do at this point? There's a good shop in town I could take it to a but I like fixing things myself if I can.
 
#2
On a Jazz bass, you should get the least amount of buzzing with both pickup volumes full on, the tone control (the third knob) full off, and your hands touching the strings. Can you try that setting for me please to see if it is the least noisy, indicating that your bass is correctly wired?

You should also check the room for sources of electromagnetic interference. For example lights on a dimmer switch can cause a lot of noise. Sometimes you can make the buzzing go away by facing in a different direction when you play, or by plugging in to a different electrical outlet.
 
#3
Mushroo said:
On a Jazz bass, you should get the least amount of buzzing with both pickup volumes full on, the tone control (the third knob) full off, and your hands touching the strings. Can you try that setting for me please to see if it is the least noisy, indicating that your bass is correctly wired?

You should also check the room for sources of electromagnetic interference. For example lights on a dimmer switch can cause a lot of noise. Sometimes you can make the buzzing go away by facing in a different direction when you play, or by plugging in to a different electrical outlet.
Click to expand...
Mushroo said:
On a Jazz bass, you should get the least amount of buzzing with both pickup volumes full on, the tone control (the third knob) full off, and your hands touching the strings. Can you try that setting for me please to see if it is the least noisy, indicating that your bass is correctly wired?

You should also check the room for sources of electromagnetic interference. For example lights on a dimmer switch can cause a lot of noise. Sometimes you can make the buzzing go away by facing in a different direction when you play, or by plugging in to a different electrical outlet.
Click to expand...

Yeah, so the situation you described is the best sound. First 2 knobs balanced, the third knob off, hand touching the string.

There's tons of wifi going on in my house, but I have this issue with this bass no matter where I go with it.

The main thing isn't a general hum, it only occurs if i use the third knob AT ALL. It gets progressively worse as I turn the knob up further.
 
#6
Turnaround said:
Sounds like a bad ground connection somewhere. Check all ground connections. Is there a ground wire going to one lug of the output jack?
Click to expand...

Hmm, I don't recall there being a black wire on the jack... I have pics of the original.
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#8
Aaron Crawford said:
Oh, so according to this diagram:
Bass Bench: Cheap and Easy Bass Mods
I'm missing a ground wire (Black) from my 3rd knob to the jack... Looks like I need to add one... Anyone disagree?
Click to expand...
And add a jumper wire connecting the back of the first pot to the second and from the second to the third. Right now the circuit is relying on the mechanical connection of the pots and jack to the base plate as the circuit ground - that can lead to noise issues.
 
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#11
Aaron Crawford said:
So I bought a second hand but nearly new bass guitar last year. I've noticed as lot of hum from it but at first put it off as a part of the design. Im not sure when it happened but now if I engage the 3rd knob at all it gets bad static that wanes a bit if my hands are on the strings.

I assumed it was a pickup issue so I bought some 60's fender jazz pickups and installed them... The new pickups sound great! But now the buzzing is even worse.... I think the new more sensitive pickups are just catching it more...

What should I do at this point? There's a good shop in town I could take it to a but I like fixing things myself if I can.
Click to expand...

It's really strange that someone who calls the tone knob "the third knob" would try to repair their own bass. Are you interested in playing it or are you just into fixing electronics? There was no reason to replace the pickups right away with learning about how pickups work. A bit of hum is an inherent flaw in the way stock Jazz Bass pickups function. At the very least you could've taken it to a tech for a diagnosis and then done the work yourself or at least posted your question on a website like this one before buying new pickups.
 
#14
matante said:
It's really strange that someone who calls the tone knob "the third knob" would try to repair their own bass. Are you interested in playing it or are you just into fixing electronics? There was no reason to replace the pickups right away with learning about how pickups work. A bit of hum is an inherent flaw in the way stock Jazz Bass pickups function. At the very least you could've taken it to a tech for a diagnosis and then done the work yourself or at least posted your question on a website like this one before buying new pickups.
Click to expand...
Well, you can judge me for not being what you expect all you want lol, but I wanted to change the pickups regardless so I thought I was killing 2 birds with one stone. I also prefer to work on my own equipment and learn by doing. You can nose up at that all you want, won't affect me much. It's not just a bit of hum, it's a crazy unacceptable amount of noise and static as was stated in my op.
 
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#16
Aaron Crawford said:
Well, you can judge me for not being what you expect all you want lol, but I wanted to change the pickups regardless so I thought I was killing 2 birds with one stone. I also prefer to work on my own equipment and learn by doing. You can nose up at that all you want, won't affect me much. It's not just a bit of hum, it's a crazy unacceptable amount of noise and static as was stated in my op.
Click to expand...

No judgement on you as a person, it's just a really strange post. It's like someone buying a car and deciding it needs a new engine before they've learned how to drive, and without consulting a mechanic.
 
#17
matante said:
No judgement on you as a person, it's just a really strange post. It's like someone buying a car and deciding it needs a new engine before they've learned how to drive, and without consulting a mechanic.
Click to expand...
You are also assuming I did zero research because I didn't memorize the name of a knob or post here first? I researched how to change pickups because I wanted to do that regardless if the other issue. I also was hoping that the noise issue would go away once I had finished. Since that is not the case I'm now researching the hum issue specifically... So yeah, I decided to change the pickups to Fender 60's jazz, saw the simplicity of the internals while changing them, and decided to reach out here instead of going straight to a shop.

I've owned the bass for over a year and I've played it at my gigs. The pickups have always seemed a bit weak to me. The decision to replace them was unrelated to the hum issue. I was just slightly hopeful that doing so would also help with the hum. Sorry if that wasn't clear?
 
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