What? You Don't LIKE Ground Noise?

  • Thread starter Thread starter StuGort
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I have an assortment of voltage-controlled synth gear. An old trick from the modular days is using galvanic skin resistance as a random CV source to control oscillator pitch, LFO rate, or filter, or whatever. The idea that skin and the human body conduct electricity and/or interfere with RF isn't a new concept. It's what makes a Theremin possible.

Theremin - Wikipedia, the free encyclopedia
 
People have read about GSP, and have concluded that it is relevant to the subject of low impedance earth paths. There is also some evidence that because of simple sweat, the low impedance path to earth follows the epidermis, rather than flowing through the body mass and in particular muscles. The grounding of a body in this way also causes reductions in the RF strength of radio mics, as the body becomes an effective absorber at near microwave frequencies. To a degree, the body will tend to sink what it touches to earth. This is good for hum, and bad for a risk assessment on susceptibility to shocks.

What I do not understand is the unwillingness to take on board that shocks are not rare, but common, and it is only luck that far more do not become fatal.

There is some confusion of the type of electricity supply that can be in place. It certainly is likely that with modern systems, the ground and neutral will be bonded together close to the consumer unit, but in larger buildings, this earth point may well be some way from individual distribution points and as the applied load changes, the neutral and earth can lift away from each other. This is the start of the audio industries ground loop problem, because the potential between Earth and neutral is different at many places, and the audio ground connection provides and alternate path that current can flow in. So all these guitar amps in one socket outlet, and a PA in another can mean that your lips can detect this few volts. Sometimes, you can even get it to spark when you touch one to the other. Unless you actually lose the neutral the supply system is unlikely to cause a dangerous fault condition, but it does happen in TV studios and other venues like theatres when people are using temporary distribution systems, or worse, when people are using 3 phase electricity, and then losing a neutral can be VERY bad news. From time to time, in less developed countries you might find that our UK 230V requirement comes from wiring across two lower voltage phases - this time both live and 'neutral' are quite separate, and neutral, should be the centre point of the star connection, but sometimes, as in Europe 110 isn't much use, the neutral is ignored and isn't tied to anything.


I think the point we're trying to make is that unless you understand how the power supply being used is derived, being physically attached to it is simply a stupid idea. Nothing to do with using the body as a screen, or low impedance bag of mostly water, simply ensuring the body's potential is independent enough to not provide the dangerous low impedance path for fault current. Is a 30, or 100mA trip enough? Will it actually break the circuit in the circumstances set out on stage? Back in the 50s and 60s, engineers were taught to keep a hand in their pocket when working on equipment with HT supplies. It made sense then, why not now?
 
I know shit about electricity. But I WANT to stick a wire down my pants and attach it to my balls. Is that so wrong? :eek:
 
When PC's became widespread in commerce there was an extreme increase in loss of neutrals in transformers for some very large companies. The source of these failures turned out to be a combination of a wiring method that used to be called a "full boat" which was three phase conductors grouped with a single neutral and the load switching power supplies used with computers. In real time the computer power supply was doing what it was supposed to do--- switch on and off with demand. The problem was that the neutral "saw" this as a solid continuous load, and the result was the literal melting and failure of the center-tap on large commercial/industrial Y-connected transformers. This problem became known as "harmonics" in electrical distribution systems.

The NEC remedy for this at first was over-sizing the neutral, and when that didn't fully address the problem the remedy became a requirement for individual neutrals for every branch circuit phase conductor, which is now standard practice in commercial and TI electrical installations. Also, the size of neutral busses in transformers have been increased, and harmonic filtering is now common too.

I point this out to illustrate that due to technology and research both the code and accepted practice change over time. What was acceptable 30-40 years ago was proven in practice to be insufficient. People take for granted that things are the way they are often without realizing there is solid research and documented failures that lead to current understanding.

HARMONICS
 
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I think the OP is desperately trying to justify his copper plate as a new must-have product for guitarists.

Good luck getting a UL-approved sticker on that copper paddle. :laughings:
 
I thought guys only put wax on their bowling balls...I guess I was wrong.
 
c7sus said:
You're talking about nomenclature. The guitar is grounded, not the player.
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No? The bridge is grounded...the strings are grounded...but when you touch them you're NOT grounded? Since I'm just stuck in rut of nomenclature...you're going to have to explain that to me.

c7sus said:
Show me anywhere in the NEC where it is recommended that a person ground themselves in relation to any circuit.
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I tell you what. Please use your own words to describe what happens to make your signal quieter when you touch your guitar. I'd love to hear this explained in a way that didn't sound like what I've been saying this whole time. I'm pretty sure the NEC (industry code produced for fire safety) isn't going into any detail to help explain this.

c7sus said:
Can you predict in advance when components of a circuit will fail and short to ground? The problem you are trying to address with your galvanic gizmo is much better addressed with isolating transformers than with a chunk of copper applied to your ass.
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So...tell me what I should do to further isolate the myriad magnetic and electric fields generated by my rack components and other sources when each of them is built assuming a firm commitment to modern grounding standards. I'm serious. I have every line level signal WELL isolated from current and I exclusively use quality connections (XLR or TRS) to make sure lines are protected. Every piece of equipment is relatively new and nothing is running without a ground prong except the dc powered gear. When I built my shop I had all the electrical built outside the walls....so there isn't ANY aspect of the grounding of this studio that isn't instantly discernible.

I have a tiny bit of noise in the system that this addresses.

You are responding to me as if picking up a guitar doesn't result in a quieter signal...when virtually everyone reading this knows exactly what I'm talking about. You are also arguing against a practice that could be made AS SAFE as simply holding the guitar...with a quick disconnect.

Everybody...hold your guitars and listen. Then lick your hand touch the bridge and listen. Then come back here and tell me once again that I don't have a point.

Damn.
 
StuGort said:
Everybody...hold your guitars and listen.
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StuGort said:
Then lick your hand touch the bridge and listen. Then come back here and tell me once again that I don't have a point.
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Now explain it again....why are you licking your hand?

What's your point?

StuGort said:
I have a tiny bit of noise in the system that this addresses.
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Maybe you're over-complicating things then...just turn up the volume a tad and I bet the noise will be irrelevent other than when you're just standing there holding the guitar without your licked hand on the bridge.
 
Oh I figured it out long before you did...I can guarantee you that. I don't lick my hand when I play or stick wires down my pants or any such nonsense.

I think in your case, instead of a copper plate with wire....try a long copper probe, like a short ground rod...and then stick it where it's wet-n-warm. That way you won't have to lick your hand any more.

The stupidity here isn't that you've used a ground wire to tame some noise...I mean, do it for the moment, cut your track, and move on.
The stupidity is that 1.) you think you've discovered a solution that has escaped countless players and guitar/amp builders over the years, and 2.) you're going on and on about it on a forum.
Like I said, cut your tracks, and then lose the wire...stop selling it like it's something terrific.
 
miroslav said:
I don't lick my hand when I play or stick wires down my pants or any such nonsense.
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Given as much public masturbation as can be viewed on this site...I suppose it's no surprise when the mention of a "waistband" morphs into butt plugs and other such probes.
 
StuGort said:
No? The bridge is grounded...the strings are grounded...but when you touch them you're NOT grounded? Since I'm just stuck in rut of nomenclature...you're going to have to explain that to me.



I tell you what. Please use your own words to describe what happens to make your signal quieter when you touch your guitar. I'd love to hear this explained in a way that didn't sound like what I've been saying this whole time. I'm pretty sure the NEC (industry code produced for fire safety) isn't going into any detail to help explain this.



So...tell me what I should do to further isolate the myriad magnetic and electric fields generated by my rack components and other sources when each of them is built assuming a firm commitment to modern grounding standards. I'm serious. I have every line level signal WELL isolated from current and I exclusively use quality connections (XLR or TRS) to make sure lines are protected. Every piece of equipment is relatively new and nothing is running without a ground prong except the dc powered gear. When I built my shop I had all the electrical built outside the walls....so there isn't ANY aspect of the grounding of this studio that isn't instantly discernible.

I have a tiny bit of noise in the system that this addresses.

You are responding to me as if picking up a guitar doesn't result in a quieter signal...when virtually everyone reading this knows exactly what I'm talking about. You are also arguing against a practice that could be made AS SAFE as simply holding the guitar...with a quick disconnect.

Everybody...hold your guitars and listen. Then lick your hand touch the bridge and listen. Then come back here and tell me once again that I don't have a point.

Damn.
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In the technical definition of "grounded", no you're not. You can insist all you want on this point, but in engineering terms and for all practical purposes your insistence does not over-ride the technical aspects of the grounding of devices and circuits.

I already told you how to correctly and safely address the issue.

ISOLATING TRANSFORMER.

I have a selection of tube amps and haven't had the problem you are going on and on about. You haven't posted a clip of the noise, and otherwise we have no clue as to what you are running and why this is such a huge problem for you. If this works for you and you are happy with it by all means do whatever you want to do.

But don't come on a BBS and advocate that others try this in their setups that you have no idea what kind of grounding they have on their power, or the condition of their gear, or anything else for that matter about what anybody else is doing.

Do you have fluorescent lighting or dimmers in your shop?

The magnetic field generated by rack equipment is minor at best. If that is the source of the problem (which I highly doubt) then MOVE AWAY FROM THE RACK!

The single noisiest items in my setup are BBD delays, and that's just the nature of BBD chips and it's part of their "sound". There is nothing particularly notable about the wiring of my house, it was done over 20 years ago to the NEC at that time.

What does "instantly discernible" mean in reference to looking at something enclosed in a pipe or a box and KNOWING that it is properly grounded?

Just because stuff is "new" doesn't mean it may not have a negative impact on noise. Do you use power conditioning? And I don't mean a crappy $99 conditioner, I mean something like a Furman AR1215 that outputs a regulated voltage and actually cleans up harmonic noise. A bunch of wallwarts add noise to any system, even when devices plugged into them are switched off. So do refrigerators and heat pumps and AC and everything else in your house. And well pumps and septic pumps and anything else you can think of.
 
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Also LOL@ "dead quiet".

We're talking about AMPLIFIERS.

Try lowering your expectations.

What really matters is that your noise floor is far enough below the dynamics of the program material so as to not be a distraction.

8 Watts is Loud Enough | Magnetic Blog
 
I don't know what all the fuss is over. I've got several guitars and none of them make any noise whatsoever that my noise gates don't rectify if I set them correctly. Why bother with 100+ posts to determine whether or not ANYTHING will reduce a miniscule amount of hum? It's rock and roll, baby!
 
Over 100 posts about something that, for me, doesn't even exist. What a waste of effort.
 
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