Shielding wasn't the problem...

[Dennis99]

I have been having problems with a fuzz sound when the amp is turned up fairly loud. The fuzz goes away when I touch the strings, bridge or tuning pegs. I assumed this was a static problem on my new CV Jazz. So, I order the copper shielding tape from Stewmac and spent about 4 hours shielding the bejezus out of the thing. That didn't fix the problem.

Then I decided to investigate further only to find that all my basses and guitars have the exact problem on multiple amp/cable configurations. The only commonality to the environment is the power source and location. I play in my basement on a concrete floor and am usually barefoot.

Anyone have this problem? I'm sure this is a commonly asked question, but couldn't find a fitting solution in my search.

Thanks!

[Dennis99]

Here's an interesting update, for which, some other user experience would be very helpful. First off, I've tried about 10 other outlets in my home with the same problem. I then measured the resistance of the wall "ground" plug to another ground = ZERO ohms. However, when I power on the amp and measure from the instrument cable shield to wall ground, I get 30k ohms. The cable by itself is ZERO. This occurs on both bass amps that I'm testing with.

I also tested on a guitar amp from instrument cable shield to wall ground and it was ZERO, but I have the same problem.

The only thing I can think of is the house wiring. It's not the bass, amp, or cables. I'll have to test at a friends next I suppose.

[Stumbo]

Do you get the fuzz at performances?

Any TB electricians want to chime in?

Maybe your whole house is not grounded properly?

[Dennis99]

I haven't noticed, because to detect this static issue, the amp has to be loud (I play at church) or completely isolated sound. I first noticed when recording into pro tools. IE happens straight into digidesign interface also: bass->BDDI->Mbox

[butchblack]

Two things to check. First I'd make sure that the grounding from your bridge to your jack and pots is good, Second, try your amp at another location as you could have bad wiring in your house.

[koobie]

I wouldn't recommend playing in bare feet on a concrete basement floor. I'd wear sandals, anything to lessen the chance of getting shocked.

[Dennis99]

Originally Posted by butchblack

Two things to check. First I'd make sure that the grounding from your bridge to your jack and pots is good, Second, try your amp at another location as you could have bad wiring in your house.

Yeah, that all checked out when I did the shielding job. I doubled checked it again yesterday as well. I'm pretty certain it's the wiring now. I've tried multiple amps, multiple outlets and multiple guitars.

I guess what I am trying to confirm is that some amount of static noise is NOT normal, right? As I mention, it's only noticeable if I have the amp really cranked or when wearing monitoring headphones while recording. The noise goes away when touching the strings (or other conductive metal on the bass).

[mongo2]

Originally Posted by koobie

I wouldn't recommend playing in bare feet on a concrete basement floor. I'd wear sandals, anything to lessen the chance of getting shocked.

+ Infinity.

Playing barefoot on concrete can kill you if there's a fault in your gear or the house wiring.

[ProfGumby]

Originally Posted by koobie

I wouldn't recommend playing in bare feet on a concrete basement floor. I'd wear sandals, anything to lessen the chance of getting shocked.

I'll second that! If there is a ground problem one is asking for trouble playing with bare feet on the basement floor.

[Pilgrim]

Originally Posted by mongo2

+ Infinity.

Playing barefoot on concrete can kill you if there's a fault in your gear or the house wiring.

Yes, indeed. Closest I've ever come to getting a truly dangerous shock was touching an old 50's light switch while on a concrete floor with bare feet - concrete can be electrically conductive.

I second the idea of checking ground paths between pickups and bridge. Sounds like possibly there is no ground connection there, which is a frequent cause of noise that goes away when touching the strings.

[varunkapahi]

yeah its the noise issue even i get from the most instruments when turned up loud, its to do with noise and grounding issues not just in the bass but they could be in the house's electricity or wiring. etc

[huben94]

http://www.amazon.com/Gardner-GFI-50.../dp/B00004WLJM

Check your outlets with something like this

R

[BurningSkies]

Originally Posted by mongo2

+ Infinity.

Playing barefoot on concrete can kill you if there's a fault in your gear or the house wiring.

Originally Posted by ProfGumby

I'll second that! If there is a ground problem one is asking for trouble playing with bare feet on the basement floor.

+ a bunch.

You're nuts if you keep playing bare foot on concrete. I carry a rubberized floor mat for gigging situations that present this situation. Don't play on bare earth either.

[gumtownbassman]

The concrete floor is most likely more grounded than your house wiring.
The hum at full volume is normal anyway, it's possibly due to the amount of gain you are trying to achieve.
Being a jazz clone, it may have single coil pickups which are prone to receiving noise too.

Try wrapping a bit of wire around the input plug into the front of your amp a connect the other end to something metal connected to the concrete floor, this will bond your bass to the same potential as the surrounding environment, and should eliminate a lot of the noise.

[Dennis99]

Originally Posted by BurningSkies

+ a bunch.

You're nuts if you keep playing bare foot on concrete. I carry a rubberized floor mat for gigging situations that present this situation. Don't play on bare earth either.

Jeez... I haven't given this much thought really. I suppose I thought we're talking minimal voltages created by pickups which is then "amplified" by your amp. That amplification shouldn't reach out and grab me (in theory). To me this is the equivalent of not being on the phone during a electrical storm, right? (Actually, I see more potential problem with that). However, out of my newly developed paranoia, I'll be wearing shoes.

[mongo2]

Originally Posted by Dennis99

Jeez... I haven't given this much thought really. I suppose I thought we're talking minimal voltages created by pickups which is then "amplified" by your amp. That amplification shouldn't reach out and grab me (in theory). To me this is the equivalent of not being on the phone during a electrical storm, right? (Actually, I see more potential problem with that). However, out of my newly developed paranoia, I'll be wearing shoes.

The problem isn't the low voltage output of the guitar, it's the potential differences that can be the result of a fault somewhere in the system.

Standing barefoot on the concrete floor and touching the grounded metal strings or other grounded parts of your instrument, mic, amp, etc. makes you an integral part of that system and a very likely path to ground for any fault current.

Don't be paranoid, just wear shoes.

[Dennis99]

Originally Posted by mongo2

The problem isn't the low voltage output of the guitar, it's the potential differences that can be the result of a fault somewhere in the system.

Standing barefoot on the concrete floor and touching the grounded metal strings or other grounded parts of your instrument, mic, amp, etc. makes you an integral part of that system and a very likely path to ground for any fault current.

Don't be paranoid, just wear shoes.

Thanks! I was an electrician in the Navy myself and do know the basics of voltage, current and resistance. I am probably just being unnecessarily risky by realizing how unlikely a shock would be. But, all the same, it's good advice and will likely solve the interim problem of grounding noise.

[lethargytartare]

Everything cranked to get the noise, and the noise goes away when you touch the strings -- might just be an unavoidable level of noise. At high volumes, most of my equipment starts to get a little noisy.

Properly grounded and shielded, you SHOULD get it to near-absolute-silence, but even some experts I've read will say that very now and then there's an instrument that just won't get that perfectly silent.

The touch-strings-then-silent situation works like this: your body acts like an antenna for noise. You are positioned right up next to the electronics of your bass, so the noise you attract gets into your circuit. When you touch the strings, you are actually shunting all that noise to ground, by way of the bridge ground wire, which is why it gets silent. And that's why you also know your bridge ground wire is fine -- if it weren't, the noise wouldn't change when you touched the strings.

There's also the matter of ground loops, which I can't explain well -- but when you shielded, did you leave wires soldered to the backs of the pots? That's what can cause ground loops, which can cause noise issues. There's a great DIY guide on the web called "Quieting the Beast" that gives some great explanations for all this, and some great solutions -- including a way to protect yourself from the electrical hazard everyone is warning you about as well (although, shoes when playing poorly grounded gear is just a smart thing to do!) Here's that guide:

http://www.guitarnuts.com/wiring/shielding/shield3.php

I have done this to many instruments, and have always had great results -- the best was fixing my buddy's guitar so that he could leave it on its stand, near an amp, at full volume, and not a peep of static or noise came from his amp...he was blown away by how much noise he had been coping with before...

Someone else said it already, but if you think it's your house's wiring, take your rig to other places and try to recreate the setting. I just can't think of any situation where house wiring would cause a problem that goes away when you touch the strings.

Good luck, man!

ltt

[Dennis99]

LTT, thanks! That was very helpful!