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Fender Jazz bass

Scotty DelMar

Scotty DelMar

Feb 2, 2008
137
22
Denver, Co.
#1
I'm posting this for a friend since my knowledge of Jazz basses is limited at best. Any input would be appreciated.

I don't know if I have a problem with my Fender Jazz or not but here are the symptoms:
The tone control doesn't seem to be working because when I crank it all the way up, there is no difference in the sound that comes out of the bass. I tried lubricating it but no difference.
When I roll back one of the pickup knobs but keep the other turned up and have the tone knob turned up I get that 60 cycle hum noise but when I back off the tone knob it goes away.
If I have both pickup knobs turned all the way up and then turn the tone knob up there is no noise other than an increase in 'string' noise.
Do I have a problem ?
 
#2
No verdict yet. What lube did you use? Make sure to use a cleaner/lubricant spray. Radio Shack has some that works pretty good if you don't have any thing else. Make sure and loosen the control plate to access the controls from the bottom side. You'll see that they have partial openings at the very bottom. Spray in these openings. Then spray the shaft. Then immediately rotate the control numerous times back and forth.

Hum noise could be a shielding issue, or possible a wire that's out of sorts.

If none of this helps, might be time for a new pot or so and maybe a trip to a tech that sort out wiring issues.

You can find shielding info here and under Google.

Good luck.
 
#3
Sounds like a Jazz bass to me! Well unless the 60 cycle hum is so loud you can't hear the bass. Turn off the old TV or fluorescent lighting and try again? The tone knob might not sound like it is doing much, but from 0 to 10 there should be a difference and that difference might just sound like extra string noise. I have my tone on 3 or so, but if it was on 1 or 5 I probably wouldn't notice any difference. Maybe the EQ on your amp is overriding any tone pot subtleties, try it with flat EQ on your amp.
 
#7
If you're getting electrical interference from somewhere (dimmers, etc.) then with a Jazz you can expect hum when only one of the pickups is turned up, so - with the tone all the way up - turn up just the front pickup. Hum? Now turn that down and turn up the bridge pickup. Hum? You should have had hum in both scenarios. Turn both pickups all the way up. Should be no hum.

If the hum goes away when you turn the tone control down that might be an indication that the tone control is working properly, but it could be something else, maybe a knackered pot. I had a P bass with a broken tone pot once and it sounded normal with the tone control fully open but when I turned the tone down the bass went silent.

Either way it's cheap and easy to replace the electronics on a passive bass so don't worry about it too much. If it does just need a new tone pot that's a half hour job at most.
 
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#10
When your strings are very old it is hard to hear a difference sometimes in the tone control, or when you have flatwound strings. Also, the hum, it is hard to get rid off, passive single coil pickups hum, shielding will help, but a hum gate pedal should do the trick
 
#11
I'm curious for those who've at least peeked into the control plate cavity: do your pups (both of them, I mean) have two grounds running? I seem to have that in my Squier Jazz (not to mention the conductive paint coating the cavity) and I only have hum when I really crank the gain on my amp on one pup solo.

Other than that, I've had no problems with hum.
 
#13
Scotty DelMar said:
I'm posting this for a friend since my knowledge of Jazz basses is limited at best. Any input would be appreciated.

I don't know if I have a problem with my Fender Jazz or not but here are the symptoms:
The tone control doesn't seem to be working because when I crank it all the way up, there is no difference in the sound that comes out of the bass. I tried lubricating it but no difference.
When I roll back one of the pickup knobs but keep the other turned up and have the tone knob turned up I get that 60 cycle hum noise but when I back off the tone knob it goes away.
If I have both pickup knobs turned all the way up and then turn the tone knob up there is no noise other than an increase in 'string' noise.
Do I have a problem ?
Click to expand...
No, the hum is normal. Jazz Bass pickups are reverse wound reverse polarity, essentially they are a big humbucker with the coils wired in parallel. Of course, when you split the coils on a humbucker the hum comes back, and that's essentially what you're doing by turning a pickup down. As a lifelong Jazz Bass player, I've never personally found it to be a problem. If that really bugs you the only solution is to install hum cancelling Jazz Bass replacement pickups like DiMarzio Virtual J, Model J, Duncan Classic Stacks, Fralin Split Jazz, etc. If the bass seems abnormally noisy, check for continuity to see if you have a good ground between the strings and bridge (active pickups like EMGs should not have a string ground but all passive instruments must have it, but since EMGs are very quiet I'm assuming you don't have those in your bass). If you have a mulimeter this is easy to do. Re the tone control, sounds like that may not be working right. Check for a loose wire or capacitor. A bad capacitor or tone pot are also possibilities, a simple fix if so. Keep in mind that in a passive circuit you can't actually add treble or bass, all you can do is roll off treble, but you should definitely hear the treble being cut with the tone control turned all the way down.
 
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#15
You could also opt to shield the bass. Done properly and completely, that will kill all your hum, and let you really hear what your bass sounds like. And before you say, "It has shielding paint" or "It has a copper plate in the cavity" that doesn't completely shield the bass, and paint, IMO, does very little, if anything appreciable, to shield the bass. Get yourself the Stew-Mac shielding kit if you're OK with a soldering iron, or take it to a qualified tech. Your bass will love you for it.
 
#16
BassShark said:
No, the hum is normal. Jazz Bass pickups are reverse wound reverse polarity, essentially they are a big humbucker with the coils wired in parallel. Of course, when you split the coils on a humbucker the hum comes back, and that's essentially what you're doing by turning a pickup down. As a lifelong Jazz Bass player, I've never personally found it to be a problem. If that really bugs you the only solution is to install hum cancelling Jazz Bass replacement pickups like DiMarzio Virtual J, Model J, Duncan Classic Stacks, Fralin Split Jazz, etc. If the bass seems abnormally noisy, check for continuity to see if you have a good ground between the strings and bridge (active pickups like EMGs should not have a string ground but all passive instruments must have it, but since EMGs are very quiet I'm assuming you don't have those in your bass). If you have a mulimeter this is easy to do. Re the tone control, sounds like that may not be working right. Check for a loose wire or capacitor. A bad capacitor or tone pot are also possibilities, a simple fix if so. Keep in mind that in a passive circuit you can't actually add treble or bass, all you can do is roll off treble, but you should definitely hear the treble being cut with the tone control turned all the way down.
Click to expand...

Wow, this is essentially the summary of the jazz bass pickups' wiring explanations in a nutshell. My goodness. Well done, good sir/ma'am!
 
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#17
I hated the sound of my single coil pickup when I rolled off the bridge or neck pickup until I shielded it. After that, all of the sudden, there was the '50s Pbass sound rolling out of my cabinet and I had an unashamedly pleasant stirring in my nether regions.
 
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#19
I don't understand the 75%-25%, or whatever balance on the two volume controls.

I've never run a Jazz bass at anything but all three controls at 100%, unless I use the rear pup only and the tone and 0 for "that" sound. The "All at 100%" is the Jazz bass sound.

Any other mix or balance in indistinctive and ill-defined to me.

Spray cleaner isn't going to solve the tone control problem. Either the cap is disconnected, as someone else pointed out, or the pot is bad, but not bad enough to kill the sound altogether.

The original pups are subject to picking up hum and noise. What worked best for me was to replace the stock pups with a pair of the hum bucker-style pups. The Nordstrand NJ5FS worked very well for me, solving most of my hum issues and still sounding very much like the original pups.
 
#20
Geri O said:
I don't understand the 75%-25%, or whatever balance on the two volume controls.

I've never run a Jazz bass at anything but all three controls at 100%, unless I use the rear pup only and the tone and 0 for "that" sound. The "All at 100%" is the Jazz bass sound.

Any other mix or balance in indistinctive and ill-defined to me.
Click to expand...

There are some other great Jazz bass sounds - Yes, everything wide open is the archetypal Jazz sound, but there's the Jaco sound with just the bridge pickup fully open and the tone control at 50%, while played directly over the bridge pickup. You can play a Jazz on just the front pickup with the tone completely off for some serious vintage db sounds or palm muted.

There are many options. :)
 

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