Good evening. After suggestions here on the forum, I finally decided to change the electrics on my Japanese Steve Harris. I bought a pre-assembled kit with CTS 500k and 250k potentiometers, Russian Pio oil capacitor, treble bleed, switchcraft jack, and Vintage Gavitt cloth wiring. Well, I tested the bass today with Steve Harris' Sansamp and brand new strings, and I still found a lot of noise. I'm very disappointed, because I thought that changing the electrics would solve my problem. I can't understand, because everyone I see using the same bass as mine never has any noise! The recordings are extremely clean, and mine sounds like a hum factory. Could it be the Seymour Duncan SPB-1 pickups? I confess that I'm already giving up on this bass and I'm extremely disappointed...
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Fender Steve Harris hum after changing electrics
- Thread starter Asllan Pizzatto
- Start date
That sounds like a grounding issue. I would check all the ground connections. At the pickup, the pots, and each end of the bridge ground.
A Precision Bass should be buzz free!
A Precision Bass should be buzz free!
First, make sure the noise is coming from the bass and not the cable, amp, amp power cord, sansamp, wall outlet, etc.
D
It does sound like it might be a grounding issue, which could be caused by a number of things, inside your bass or somewhere else. Replacing the entire wiring inside the bass to solve a ground related hum is poor advice IMO. It it had worked it would have been blind luck.
Was the new wiring installed by a professional luthier/guitar tech, or by someone without the experience to spot any OTHER potential issues inside your bass?
Is the bridge on your bass properly grounded?
Are the pickup/control cavities shielded, and if they are, is the shielding properly grounded (without introducing any ground loops)?
Have you tested your setup with a different bass, and if you have, was is silent?
What's the rest of your signal chain?
Have you tested this bass in a different location, or with a different setup? Was it silent?
You mentioned recording. Is your recording setup grounded? A usb-powered interface + a laptop with an ungrounded power cable can definitely introduce hum unless your bass is grounded through something else.
If you only use the bass for recording at home, is there anything nearby that could introduce hum, like lights or other electrical appliances, and is the grounding in your home ok?
Is there any difference if you switch on/off the ground lift on the Sansamp?
Pics of the wiring inside your bass MIGHT be helpful.
Was the new wiring installed by a professional luthier/guitar tech, or by someone without the experience to spot any OTHER potential issues inside your bass?
Is the bridge on your bass properly grounded?
Are the pickup/control cavities shielded, and if they are, is the shielding properly grounded (without introducing any ground loops)?
Have you tested your setup with a different bass, and if you have, was is silent?
What's the rest of your signal chain?
Have you tested this bass in a different location, or with a different setup? Was it silent?
You mentioned recording. Is your recording setup grounded? A usb-powered interface + a laptop with an ungrounded power cable can definitely introduce hum unless your bass is grounded through something else.
If you only use the bass for recording at home, is there anything nearby that could introduce hum, like lights or other electrical appliances, and is the grounding in your home ok?
Is there any difference if you switch on/off the ground lift on the Sansamp?
Pics of the wiring inside your bass MIGHT be helpful.
D
While running a ground wire between those two pots will theoretically introduce a ground loop, I have NEVER found this to be a problem with passive guitars/basses. Personally I would much rather have that extra ground wire there, than relying on the mechanical connection between the pots/control plate. If one of those pots come even SLIGHTLY loose during a gig you can get crackling and potential dropouts without the extra ground wire. The same goes for J-basses and other guitars/basses with metal control plates.
I'm not saying Fralin is wrong. They definitely know more about pickups&wiring than me. I can only say what works for ME, in real world situations, rather than in theory.
@OP
Plug the bass into the amp and don't touch the bass afterwards. Is there noise coming from the speaker? If there is noise, than proceed to touch the strings. If the noise lessens or dissipates entirely than there is a shielding issue. Conversely, if the bass is quiet plugged in and not touched, but becomes noisy when you touch the strings, there is a problem with ground somewhere in the circuit. Try this approach and post what you noticed
Plug the bass into the amp and don't touch the bass afterwards. Is there noise coming from the speaker? If there is noise, than proceed to touch the strings. If the noise lessens or dissipates entirely than there is a shielding issue. Conversely, if the bass is quiet plugged in and not touched, but becomes noisy when you touch the strings, there is a problem with ground somewhere in the circuit. Try this approach and post what you noticed
As has been said above, did you eliminate all other possible sources of hum? No pedals between your bass and amp, and did you try another amp, another cable? Do you have other basses that do not hum on your setup?
Also, make sure that you do not have any lighting with dimmer switches on the same power group, et cetera. The Sansamp should be very quiet normally.
Maybe a sound clip or small movie recording of the hum would help us for better advice.
Also, make sure that you do not have any lighting with dimmer switches on the same power group, et cetera. The Sansamp should be very quiet normally.
Maybe a sound clip or small movie recording of the hum would help us for better advice.
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As someone who designed audio gear for a living (including dealing with a bunch of interesting ground loop scenarios), I can assure you that, while a bass guitar could be part of a ground loop, you're not going to be able to create a ground loop who's effects you can hear in the internal wiring of a passive bass.
You rewired your bass. Now it's noisy. Your wiring isn't right. Make sure the strings, the shielding, the backs of the pots, and the a ground connection on the jack are sll connected to each other - using an ohmmeter. 90 percent sure if you look at all that, you'll find your problem.
D
This is all good advice, but unless I totally misunderstood the OP, I think he said the bass was also noisy BEFORE he installed the new wiring, and that the noise was the reason why he rewired it. So basically the same before/after, right?
Which suggests that the problem may also be somewhere else in his signal chain (although it could still be something inside the bass of course).
In any case, simply installing a new wiring harness without identifying the actual problem was always gonna be a pure lottery. The only way forward is to do some proper troubleshooting. The first thing I would do in this situation, if the OP hasn't already done so, would be to test the bass somewhere else, with a completely different setup (including the cables) and make 100% sure the problem is actually with the BASS, rather than something else entirely, like maybe the recording setup.
Agree with the above.
If you replaced all the electronics in your bass with a brand new system, and still get hum, then the problem is probably not the bass but something else in your setup.
If you replaced all the electronics in your bass with a brand new system, and still get hum, then the problem is probably not the bass but something else in your setup.
Any P bass benefits from making sure that all things needing to be grounded ARE GROUNDED.
As @micguy said, using a multimeter is key.
Testing to make sure that all poles of the pickups, the jack sleeve, all pot casings have continuity to ground. If there is shielding, make sure that is connected to ground as well.
The hot signal should be very simple - PU+ to volume pot to jack tip.
Tone (typically) comes off the one volume lug (where the PU+ connects).
And none of THAT signal chain should connect to ground (though you'd get the opposite of sound in that case).
And yeah, if all this checks out, volume works like it should, tone works like it should, the bass is working.
Testing it elsewhere (different amp, different room or even a different place than the house) would be a good move, if you can.
If it's STILL having problems after this is all correct... maybe get tested to see if you are some kind of supernatural being who can manipulate RF signals?! Maybe I watch too many sci-fi shows, but as a tech, if all this was working and it was still a mystery, that's where my mind would wander to.
As @micguy said, using a multimeter is key.
Testing to make sure that all poles of the pickups, the jack sleeve, all pot casings have continuity to ground. If there is shielding, make sure that is connected to ground as well.
The hot signal should be very simple - PU+ to volume pot to jack tip.
Tone (typically) comes off the one volume lug (where the PU+ connects).
And none of THAT signal chain should connect to ground (though you'd get the opposite of sound in that case).
And yeah, if all this checks out, volume works like it should, tone works like it should, the bass is working.
Testing it elsewhere (different amp, different room or even a different place than the house) would be a good move, if you can.
If it's STILL having problems after this is all correct... maybe get tested to see if you are some kind of supernatural being who can manipulate RF signals?! Maybe I watch too many sci-fi shows, but as a tech, if all this was working and it was still a mystery, that's where my mind would wander to.
Ok,
Ok, check you've not got a buzz from not connecting to ground or from connecting to ground.
Pedant!
I'll respond to everything I read here: my luthier installed it and tested it with a multimeter in front of me. He assured me that everything was fine. I have another Precision with EMG HZ pickups, and I can assure you that it doesn't make any noticeable noise, using the same pedal and the same cables. About the shielding, my bass has shielding done last year with copper by the same luthier who changed the electrics, and all the luthiers I took it to told me that it was OK. That said, the situation is very complicated... I don't know what to do anymore.
Alright, then it seems that the best thing to do now, is to take your bass and your pedal to your luthier and let him hear what the problem is?
We are talking about relatively simple electronics inside the bass, a proper luthier should be able to get rid of any hum. It is also possible that the SD pickup is faulty, you could try checking that with another temporary pickup (surely a luthier has a spare P-pickup lying around?).
If you're not well-versed in electronics, take your bass to a different luthier for a second opinion.
I can tell you I also own the blue Fender Steve Harris bass with the Seymour Duncan SPB-1 and it has no issues with noise. I replaced all of the electronics with a Seymour Duncan SPB-4, CTS potentiometers (250k), a .047uf capacitor, and a Switchcraft jack. All put together with vintage fabric insulated wire. Still no issues.
The main thing I would be inclined to check is the ground wire from the electronics to the bridge. You will have to remove the bridge to check it. The ground wire comes up from the body and the metal conductor should be compressed between the bridge and the body. If that isn't right, you will have problems with noise.
There are plenty of schematics available for Precision bass wiring. You could try that to confirm that everything is as it should be.
I can tell you I also own the blue Fender Steve Harris bass with the Seymour Duncan SPB-1 and it has no issues with noise. I replaced all of the electronics with a Seymour Duncan SPB-4, CTS potentiometers (250k), a .047uf capacitor, and a Switchcraft jack. All put together with vintage fabric insulated wire. Still no issues.
The main thing I would be inclined to check is the ground wire from the electronics to the bridge. You will have to remove the bridge to check it. The ground wire comes up from the body and the metal conductor should be compressed between the bridge and the body. If that isn't right, you will have problems with noise.
There are plenty of schematics available for Precision bass wiring. You could try that to confirm that everything is as it should be.
My house was built in 1972 and has lighting dimmers that will cause pickups to make all kinds of noise. Even basses that are not known to make noise will buzz when in range of those dimmers. Just something else to consider.
Dimmers make noise like any other source - via magnetic and/or electrostatic coupling. This is a P bass, which mans it's a very simple device to troubleshoot (assuming you have the right knowledge). It has hum cancelling pickups - that should keep it quiet for magnetic coupling. If it's shielded, that will deal with the electrostatic field. Even in a house with dimmers, it should be capable of making the thing quiet. I have dimmers and a couple other odd sources (including a light with 12 LED bulbs that puts out a nasty field), and have no problems with any of my basses. Now, facing the description that the bass isn't quiet, it means something isn't right in how it's wired or shielded.
If you turn the volume control down on the bass, and it's quiet, but hums with the volume up, that means that the issue is definitely in the bass. If it still hums with the volume on the bass down all the way, then something else in the system is awry.
Just in case, there is one odd possibility I hadn't thought of before - if you wired one half of the pickup backwards, the thing would effectively be a single coil, and therefore susceptible to hum fields. Most P bass pickups come with the two halves already tied together with a wire, which makes it essentially impossible to get that wrong, but some pickups come with 4 wires, and if you're not careful, you have a 50% chance at getting it wrong.
