Mysterious Crackle Noise on Bass - Nobody can figure it out

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Flatwoundround

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May 18, 2014
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#1
So I had precision pickups put in my ibanez bass and then the active electronics were disabled so now the bass operates just like a passive precision. Problem is sometimes when I move the chord or just move it makes a terrible crackly noise. Tried numerous chords and a few amps and get the same problem so it must be the bass. I have had a few different techs and luthiers look at the bass and unfortunately the bass was not making the noise when they tried it which led me to believe it was my chord or amp but again I have ruled those out. Put a new jack in and that did not solve the problem either. It happens sometimes but not all the time, but when it does happen it happens when I move the chord but the notes do not go silent it just creates a crackle noise.

Tonight me and friend took off the back cover and for some strange reason the crackle noise went away when I was moving the chord around. We put the cover back on and the noise did start to come back but it was not nearly as bad.

What the heck could this be? Could there be a sort of static charge in there and then when the cover came off the charge got released? I had the bass doctor in chicago double check the wiring and he said it looked fine to him. Oh and i did spray some of that stuff from GC that cleans out the dust and stuff that can make this type of noise but that does not help.

Any ideas please? Thanks much.
 
#5
The number one thing to check is the input jacks of the bass and amp. If they check out then make sure there isn't a wire that is grounding to the plug or jack when the bass is plugged in. If the tech couldn't replicate it on the bass it might be the amp input.

To rule out the possibility of the noise coming from the cord try it with a different instrument. You might even check the soldering at the jacks of the cord to make sure that isn't the culprit.
 
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#6
First of all thank you for the replies.

There is no pickguard but it does seem like it could be some sort of static thing going on. That is my gut feeling about it. I have some of that spray from GC that you can spray in the jack to supposedly clean out any dust and help the connection. I did spray some of that in the Jack but did not help at all. I just find it interesting that when I opened the back up the noise went away.
Maybe a dumb question here but can I just spray it all over the inside of the back when I open? Or should I just use some compressed air to clean out any dust that could be causing static?

At first I was convinced it was the amp that was the problem but then I got the same exact issue on a different amp. Did the same thing with different chords so I conclude it must be the bass.

My gut feel is telling me there is some type of static electrical charge causing this, maybe some dust in there? Is it safe to spray all the wires with that spray from GC? I think it is but not sure.

Thanks again. I hate the thought of this thing acting up on a gig.
 
#7
It really sounds like static from the rear plastic cover, and perhaps something not grounded that should be. If you lay the bass down and touch or rub the cover - does it make the noise?

If it were the output jack, it would make the noise when you moved the plug around. Did you try a different cord?
 
#8
Bassamatic said:
It really sounds like static from the rear plastic cover, and perhaps something not grounded that should be. If you lay the bass down and touch or rub the cover - does it make the noise?

If it were the output jack, it would make the noise when you moved the plug around. Did you try a different cord?
Click to expand...

I think you are right about the static. I ruled out the jack because it was replaced even though the tech said it was fine as it was only a year old, but still I insisted on a new one. I have tried numerous cords and two different amps and same story. The ChicagoBassDoctor (this guy has worked on lots of pro bass players basses, Chris Squire and George Porter to name just a few of many many), anyway he inspected the electronics and said it looked solid, so I tend to rule out the grounding issue. Of course with my luck the bass did not make the crackling noise when he inspected it which led both of us to conclude it was my amp since we used his amp to check it - but like I said we tried another amp last night and it still made the noise.

Interesting thought about the rear plastic cover as the cause of the static. I did not think of that but that makes sense too. I think it is that or just some dust in there causing some static charge. I am going to take some compressed air and blow it all out and see if that helps. The noise got really bad last night when I was practicing with a drummer friend but then after we removed the rear plastic cover the noise was gone when the cover was off and then when I put it back on it came back but much much less and much much quiter.

This is just the kind of luck I usually have with these things.

Thanks again for the replies, I did not think about the rear plastic cover as the actual culprit. That seems to make sense given all the results I am getting.
 
#12
Somewhere on the web I read that antistatic treatment can be made with a mix of tap water, alcohol and liquid fabric softener. I have not tried it, though. I believe that also some antistatic conditioner can be found as aerosol spray.
 
#13
If the back cover has foil or a grounding covering on the inside, and it is not making good contact with the cavity ground, the intermittent connection will make a crackling sound, and moving around may cause it.
Try a folded piece of foil at the cavity edge inder the cover.
Also, are all the wires from the preamp capped and sealed so they cannot contact the cavity or cover?
 
#14
Flatwoundround said:
Cool idea, I am going to try this at home when I practice, all the wires are sort of dangling out but should be fine at home at least.

Thanks.
Click to expand...

Talked to a another Tech today and he suggested using bounce anti static towels and that I could actually put them in the back compartment with the electronics. I have never heard of an idea like this before but what the heck, i ma
 
#15
I just got off the phone with the ChicagoBassDoctor (the luthier who has worked on many many pro bass players gear) and he said he has seen this type of thing before. He said he can fix this and just for the heck I asked him if putting i
JustForSport said:
If the back cover has foil or a grounding covering on the inside, and it is not making good contact with the cavity ground, the intermittent connection will make a crackling sound, and moving around may cause it.
Try a folded piece of foil at the cavity edge inder the cover.
Also, are all the wires from the preamp capped and sealed so they cannot contact the cavity or cover?
Click to expand...

n a sheet of bounce antistatic towel inside the back housing would work and he said it should but it would only
JustForSport said:
If the back cover has foil or a grounding covering on the inside, and it is not making good contact with the cavity ground, the intermittent connection will make a crackling sound, and moving around may cause it.
Try a folded piece of foil at the cavity edge inder the cover.
Also, are all the wires from the preamp capped and sealed so they cannot contact the cavity or cover?
Click to expand...


That might be the problem and man I really appreciate everyone's ideas and feedback here. A very well respected luthier/tech did look at the electronics and he said it all looked good. I just spoke to that same guy tech today and on the phone he said he has seen this problem before. He said he can fix it by somehow using copper and correcting the ground - I am not even sure what it all meant but this guy really knows his stuff well so I feel confident he can fix. I asked him about the bounce antistatic towels being put in the casing cover and he said that would probably work but it would only be a temporary fix and he knows how to fix permanently.

I am still not 100% sure what this is but it sounds like some kind of electrical static thing caused by the back cover and I guess having a proper ground from the back cover plate to the actual ground would solve this? Thats what it sounded like he said but he mentioned putting some type of copper plate on the inside of the back cover and I think he said that would then be connected to the ground. I think this makes sense since the copper would conduct the electricity towards the ground thus stopping the crackling.

Not easy being a bass player as we not only have to learn our instrument but we have to learn all this techy science stuff too.
 
#16
The foil I refered to would be better if it was copper, but aluminum would work for now- then you would know if a better plate ground is needed. I don't think it"s tatic, but an intermittent ground.
 
#18
Does it always happen in the same place?
Like in the room with carpeting?
Carpet static? Put some fabric softener in a spray bottle and spray the carpet.
I get a bit of this now and then in my carpeted basement.
Not enough that it bugs me. But as the cable brushes across the floor, I might get a bit o' the Rice Crispy.
 
#19
JustForSport said:
If the back cover has foil or a grounding covering on the inside, and it is not making good contact with the cavity ground, the intermittent connection will make a crackling sound, and moving around may cause it.
Try a folded piece of foil at the cavity edge inder the cover.
Also, are all the wires from the preamp capped and sealed so they cannot contact the cavity or cover?
Click to expand...

Please pardon my ignorance here but I am just trying to understand how this works.
JustForSport said:
If the back cover has foil or a grounding covering on the inside, and it is not making good contact with the cavity ground, the intermittent connection will make a crackling sound, and moving around may cause it.
Try a folded piece of foil at the cavity edge inder the cover.
Also, are all the wires from the preamp capped and sealed so they cannot contact the cavity or cover?
Click to expand...

I will take a look at the back cover tonight but I thought it was just pure plastic. How could electricity be discharged to the back plastic cover? I don't understand that part but I really don't understand how this works admittedly. Since the pre-amp became disabled after the precision pickups were installed to make the bass passive would that make a difference for those wires if they were or were not capped.

Thanks again.
 
#20
If you really want to fix it, shield it.

IMG_20151224_205119-TB.jpg
 
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