Tapewounds causing electrical hum

[Pimmsley]

However, his new tapewound strings don't conduct electricity from their surface, so they're defeating the reason that the bridge ground exists. Using those tapewounds is like not having the bridge ground.

TB is correct... in effect the tapewounds are not allowing the player to be grounded, further proved with the noise going away when touching a part on the bass that is a path to ground... bridge and control plate.

put conductive strings back on (just about every other type other than tapewounds) and the problem will go away... Shielding, although great for some noise issues will not prevent the OP's issue.

 

[Troph]

If the bass is well shielded, it will make no difference if you are grounded or not, by touching the strings. The bass
will already be immune to the 60 Hz electrical signal present on yourself. If the buzz is reduced when grounding
yourself, it is therefore an indication that the bass is not shielded.

...

Or if you have ever touched the tip of a cable disconnected from the bass (and connected to an amp), you are
very likely aware of the signal present on us.

+1

 

[Troph]

TB is correct... in effect the tapewounds are not allowing the player to be grounded, further proved with the noise going away when touching a part on the bass that is a path to ground... bridge and control plate.

You don't have to be grounded! Why do you think it's necessary to be grounded?

If your bass depends on the player being grounded to avoid noise, then your bass is not shielded well, and will make noise if you stop playing and raise your hands in the air, or do something like play an open string and let it ring! How is that acceptable? I certainly don't want to be noisy when I play open strings, or reach for my beer.

Shielding, although great for some noise issues will not prevent the OP's issue.

Explain why. I'd love to hear it. Where do you think the noise is coming from?

 

[Pimmsley]

You don't have to be grounded! Why do you think it's necessary to be grounded?

If your bass depends on the player being grounded to avoid noise, then your bass is not shielded well, and will make noise if you stop playing and raise your hands in the air! How is that acceptable?

Explain why. I'd love to hear it. Where do you think the noise is coming from?

I'm not making this up... I stand by my comment.

why do you think there is a path to ground from the bridge ? can you tell me ?

Have you played through different amps and noticed some amps make more extraneous noise (buzzing humming) than others through the same bass ?
And noticed the change a ground lift button can make ?
neither of those change the shielding of the bass...
the path to ground through the strings often stops humming or buzzes that occur when you are not touching the strings, when you lift them off it comes back, ground loops can occur that cause problems for bass and guitars...

 

[Pimmsley]

oh, and the noise comes from all sorts of devices... light dimmers, cheap power adapters, most electronic equipment will emit some RF noise that is exactly what we have to deal with, stages with dodgy power wiring, air conditioners, lighting and dimmer racks etc...

 

[Pimmsley]

I do believe in shielding... I just did the control cavity in my newish Jazz... but it doesn't change the fact that the single coil pickup is basically an antenna... that's why the chrome pickup guards/covers are also connected to ground (or at least should be) on a jazz... to create a Faraday cage to shield from RF etc... if you use them

my shielding job...

Edit: sorry I was thinking of the ground wire to shield cover in the early pbass, they are not connected by default in the Jazz bass, my bad

 

[Troph]

I'm not making this up... I stand by my comment.

LOL, neither am I. And FWIW, I happen to have a master's degree in EE... so I do have some background here. (Not that it makes me automatically correct, mind you!)

why do you think there is a path to ground from the bridge ? can you tell me ?

Easy. Because if the strings weren't grounded, they would act like antennae radiating directly into the pickups, which are inductive by nature and situated directly in front of the strings only a few millimeters away. Some pickup designs are more susceptible to this sort of noise than others, but grounding the strings takes it away as a potential source. Early Gibsons did not ground the bridge due to the humbucking pickups.

Have you played through different amps and noticed some amps make more extraneous noise (buzzing humming) than others through the same bass ?
And noticed the change a ground lift button can make ?
neither of those change the shielding of the bass...

Actually, no. There is no such thing as a "ground lift" in the circuit between a bass and an amplifier. If you lifted the ground, you would be cutting current flow through the circuit and you would get no signal to the amplifier!

I think maybe you are confusing two different sources of noise here. Ground lifts and transformer isolation work to eliminate a source of noise caused by common impedance coupling, where two components share a signal cable but have separate power supplies with separate grounds. Small differences in the two "ground" potentials of the components (say, between an amp's DI output and the front-of-house mixer) interconnected by a signal cable cause the offset to be misinterpreted at the receiver as signal. But since guitars are not separately grounded from the amp, common impedance coupled noise is a complete non-factor here.

So, the only source of noise we're discussing here is due to inductive coupling. "Ground loops" in the context of inductive coupling refer to the small "circular paths" present in the ground interconnects of a guitar's circuitry. The hypothesis in this context is that these loops can result in induced currents and therefore some voltage drops, leading somehow to signal noise. I have never seen it measured appreciably, and many consider it to be well below the noise thresholds in other parts of guitar design, and therefore negligible. So ground loops really should not be part of our discussion at all.

So now we're really only talking about currents induced in the signal path (not ground path) of the guitar electronics by electromagnetic radiation, either from a primary electric source (like a fluorescent light) or from a secondary re-radiating source (like a human).

And since we're only discussing noise that goes away when the human is grounded, we're just talking about secondary re-radiating noise. This is emanating primarily from the back of the guitar, which is why shielding the electronics and pickup cavities works so well.

oh, and the noise comes from all sorts of devices... light dimmers, cheap power adapters, most electronic equipment will emit some RF noise that is exactly what we have to deal with, stages with dodgy power wiring, air conditioners, lighting and dimmer racks etc...

Exactly. And so since this noise can only enter the signal path in unshielded areas of the instrument, that is precisely why we are arguing that shielding can indeed make much of this noise (including noise radiated by our bodies) go away. Obviously some portion can obviously still get through the pickups, depending on your pickup configuration and design. But even most single-coil pickups these days offer a paired reverse-wound, reverse-polarity design that eliminates most external induced noise there. It's possible that the OP's Jaco pickups don't have this RW/RP feature and therefore they are just more susceptible to EMI... But I have a shielded Jazz that makes virtually no noise even if only one pickup is turned up... So I don't think it's the dominant factor here.

I do believe in shielding... I just did the control cavity in my newish Jazz... but it doesn't change the fact that the single coil pickup is basically an antenna... that's why the chrome pickup guards/covers are also connected to ground (or at least should be) on a jazz... to create a Faraday cage to shield from RF etc... if you use them

Sure, the single coil will certainly pick up induced interference, but not much from the player (situated to the back of the instrument) if the pickup cavities are shielded... and again, in newer pickups the second RW/RP single coil offsets a great deal of this externally induced coil noise.

 

[Pimmsley]

um... my comments were in response to the OP's first post, the noise went away when he touched the metal parts of his bass... grounding himself.
The ground lift I mentioned was in regards to ground lifts on amps etc..
I also studied electronics. Just trying to help.

 

[Pimmsley]

Troph, I am trying to understand this better...
the other night I had this exact situation at rehearsal in a different studio to the one we usually use.. and my single coil P bass was behaving the same way, I was getting a crazy amount of interference when I took my hands of the strings (not normal for this bass and amp setup)... My conclusion was that I was being grounded by touching the strings, so my body was then acting as a lesser path of resistance to ground for the interference and therefore not affecting the bass as much...

If that's not the case, then what in your opinion was going on there ?

 

[DiabolusInMusic]

Thanks for that Troph, you have made me feel a lot less crazy.

 

[Pimmsley]

Thanks for that Troph, you have made me feel a lot less crazy.

well now I'm starting to think I'm crazy...
I just re-read the whole thread and I am still back to the fact that the OP has more noise than he had with conductive strings... the only thing that has changed are the strings and the players path to ground... the noise goes when he touches a part of the bass that's connected to ground...
how has this got anything to do with shielding ?

what's going on ?

 

[petrus61]

The day I have to modify or put in extra money to accommodate strings when there are SO many other choices out there, is the day I take up the dulcimer/flute/thumb piano.

 

[Troph]

um... my comments were in response to the OP's first post, the noise went away when he touched the metal parts of his bass... grounding himself.
The ground lift I mentioned was in regards to ground lifts on amps etc..
I also studied electronics. Just trying to help.

Yes, I understand you're talking about a ground lift button on amps, but what I'm trying to explain is that those are designed to eliminate a completely different category of noise that has nothing to do with the OP's issue. Let's just agree to stop talking about those, OK?

the other night I had this exact situation at rehearsal in a different studio to the one we usually use.. and my single coil P bass was behaving the same way, I was getting a crazy amount of interference when I took my hands of the strings (not normal for this bass and amp setup)... My conclusion was that I was being grounded by touching the strings, so my body was then acting as a lesser path of resistance to ground for the interference and therefore not affecting the bass as much...

If that's not the case, then what in your opinion was going on there ?

That sounds correct to me. When you're grounded, you become a strong electrostatic monopole, which resists any induced charge movement in your body which would turn you into a weak dipole radiator. The result is that -- as long as you're touching the strings -- you are no longer radiating noise into your inadequately shielded instrument. If you take your hands off the strings, you begin radiating into the instrument once again, and due to the inadequate shielding somewhere, the signal path picks up the induced noise.

Where we disagree (I think) is in what to do about it. Lots of people here are telling the OP that he can't eliminate this noise without switching back to conductive strings. They're implying that the instrument is always going to be noisy due to this body radiation, unless the player is touching the strings and/or bridge, and therefore the strings must be conductive to stop the noise.

I disagree. A good shielding job should eliminate most of the noise radiating from the human through the back of the body into the signal electronics, rendering it unnecessary to ground yourself to get noise-free performance. So even if you go back to conductive strings, you're now free to take your hands off the bass without worrying about suddenly getting a burst of noise through your amp!

It's well known that most Fender basses come from the factory inadequately shielded, and if you want to eliminate this hum, you need to do a full shielding job.

I just re-read the whole thread and I am still back to the fact that the OP has more noise than he had with conductive strings... the only thing that has changed are the strings and the players path to ground... the noise goes when he touches a part of the bass that's connected to ground...
how has this got anything to do with shielding ?

The noise is coming from electromagnetic radiation from the player's body. That's why this has to do with shielding, since extra shielding would prevent this noise from being a factor at all, whether or not he's grounded.

He had never noticed this extra noise before because his strings were grounding him, masking the underlying noise problem. But I guarantee the problem WAS there even with his conductive strings, and taking his hands off of his previous strings is identical to installing non-conductive tapewound strings from the standpoint of getting electromagnetic interference from the player's body.

Better shielding would work whether or not the player is grounded. He could radiate all he wants, and it would have little to no effect on the instrument. That's why we think shielding is a better answer.

 

[Pimmsley]

I think we agree more than not on most points, and although I think shielding is still a good idea, I just don't think shielding will help the OP much with the issue at hand...

another example I have to offer is this:
I have two different amps.. one being a trace elliot in a metal enclosure... it's dead quiet on all basses I have, active, passive, humbucker coils and single coil basses, no noise, but, if I plug my cheap backup amp (not well shielded and in a wooden enclosure) in the same room in place of the trace elliot, I get RF and buzzing on the single coil basses, some changes when I change position of the bass and other noise is less present when the strings are touched. Both single coil basses are properly shielded (all cavities) and the only source of noise RF/interference seems to be coming from the amp. I can't shield them any more than they are... and being that the trace is dead quiet on the same basses, surely the amp is the problem source and not poor shielding. nothing else has changed.

EDIT: I also have a GK400RB, same thing, dead quiet on all basses, also in a metal enclosure...

So I agree the OP's problem would have existed before the string change (like my backup amp), but in effect the OP being un-grounded from the bass as a result of the string change is the new problem, and by re-establishing an electrical contact with the bass the buzz/noise goes away. So unless the amp is changed, using conductive strings is the only thing going to get the OP back to what he/she is used to noise wise with that amp and bass...
I bet if the OP took that bass, as is, and plugged it into a different rig the noise/buzzing result would be different.

 

[tkozal]

OP here. I did try several amps. I got the same noise with the tape wounds with ALL amps. From a little peavey practice amp,a swr combo and a LMII. When this first happened I tried different amps, cords, different rooms, etc. same thing.

 

[Pimmsley]

OP here. I did try several amps. I got the same noise with the tape wounds with ALL amps. From a little peavey practice amp,a swr combo and a LMII. When this first happened I tried different amps, cords, different rooms, etc. same thing.

Right,Ok.

I guess the only thing left is to check the the bass electronics for possible loose wiring or indeed try shielding the bass better as suggested. Just odd to me that the only thing that changed were the strings being electrically connected to you... If extra shielding fixes that, that's great ! Confuses me but awesome

Edit: just so you don't think I'm against shielding I started this thread: http://www.talkbass.com/forum/f38/slug-snail-repellent-adhesive-copper-tape-shielding-966282/

 

[96tbird]

Come on guys, this is easy. The tapewounds don't allow him to complete the ground. The buzzing stops when he touches the bridge or knobs.

There is a wire that runs from the control cavity ground to the beneath the bridge. It's meant to allow that electrical "noise" that is picked up by your guitar to be dissipated into your body.

The surface of the tapewounds are not conductive. So touching the strings doesn't eliminate the noise. That's why touching the bridge or metal knobs still stops the noise.

This this this. All other explanations and guesses are useless. Shielding, laugh. Even though its always a good thing it doesn't help when the steel of the string is covered with a non conductive nylon wrap. Even DR Black Beauties are noisy this way. It's ok though, I just swapped in Roto 66's again and hum is gone completely.

 

[Troph]

This this this. All other explanations and guesses are useless. Shielding, laugh. Even though its always a good thing it doesn't help when the steel of the string is covered with a non conductive nylon wrap. Even DR Black Beauties are noisy this way. It's ok though, I just swapped in Roto 66's again and hum is gone completely.

Your post is light on theory supporting your claim, and strong on bad advice.

 

[pkstone]

Troph is correct and clear with what he's saying here, folks. Read it and understand it, and please, stop muddying the waters. The tapewounds aren't *causing* the noise, they're highlighting a shielding problem that was masked previously by the metal strings providing a ground path which stopped the player from becoming an antenna. Relying on metal strings to do this is not a great idea.

 

[SoVeryTired]

I've not experienced this but I have read a thread about it before:

Sadowsky's views on coated strings