Can I stand on a piece of metal to ground myself instead of buying a hum eliminator?

B

Bargarcs

New member
Title. I have a Line 6 POD xt and a ZOOM R20. They are both plugged into a surge protector that claims it is grounding things. It's not, or I'm using way too much gain (I am, heh).

I'm seeing on Sweetwater a Morley Hum Exterminator for $90. But I also notice that I can touch a metal part of the ZOOM and the hum goes away. But touching it with my hand means I can't play guitar.

I have a computer grounding strap, but that (if it works in this scenario) would mess with my playing (on my wrist).

So would standing on a metal piece of some sort kill the hum? Or do I have to touch a metal piece on the equipment itself? My outlets are all 3-prong and I'm not going to defeat them.

Thank you folks, I'm getting back into home recording after like a 12-year hiatus.

EDIT: Also, the Morley Hum Exterminator has one plug on it (to plug equipment into); would I be able to chain the existing surge protector to it and then to the wall? The two pieces of equipment total 4 amps, and the Morley says it can handle up to 6. I'm a bit puzzled as to why the grounding feature of the surge protector doesn't seem to be doing its job. FYI, I'm not recording using a direct box, which would have a ground hum switch.
 
It sounds very much as though you have an "earth free" system. This is becoming more common as more kit is made without an earth (class ll insulation) to combat ground loops. The problem is, things like guitars really need to be earthed. I suggest you take a wire from the earth pin on your mains socket (make SURE it is earth!) and connect that to the metal of the line 6 or Zoom, NOT both.

Dave.
 
You could. Should you? No. Hum is usually caused by electricity getting to somewhere it shouldn’t. Tiny circulating currents flowing through the grounds and often very small. In my summer venue, if you use the old fashioned 24 way multi from the stage, very often you can hear hum. Sticking a volt meter between the stage ground through the multi, and the sound booth ground reads about 3 Volts. You could stand bare foot on your metal plate, and the hum might vanish. The problems arise when the ground is called on to do the job it is really there for - sink the full mains voltage to ground in a fault condition. So that dropped lighting dimmer pack, or the mains distro you’ve been meaning to mend for weeks suddenly has its ground raised to 240v, me being British. That metal plate you are standing on now might sting a bit ….. or kill you. Bodging grounds to cure hums is risky business. Proper distribution usually cures the problem. One source connector that splits to all your gear. The ground potential is then the same, as long as nothing is actually faulty, or poorly designed. Very often hums originate when some gear is supplied from a different socket, with different grounding. Bodge grounding, and I suspect we have all done it, really is a bad idea. Killing yourself or others is probably unlikely, but perfectly possible.
 
Do w e have a difference of opinion here Rob? I am always very careful to give safe advice. In the bad old days, ground loops would be fixed by REMOVING safety earths from equipment. That is never, ever acceptable. However, as I said, lots of kit now is class ll insulation and totally safe with no earth (many top end monitors are such) . Generally this causes little trouble in systems because something else connected to the monitors (say) WILL be grounded, a mixer perhaps or a desktop PC. But grounded gear is getting rarer and sometimes you need to provide a 'signal' earth and this is a perfectly safe thing to do. A firm even make a 13A plug top with just an earth pin for that very purpose!

All that said, attempting to diagnose noise problems remotely is always going to be a pretty futile exercise.

Dave.
 
I’ve known of guys that ran a ground wire from whatever and physically taped the wire to their stomach.

Sounds weird? Dangerous? Maybe, maybe not.

Think of it. EVERY time you pick up an electric guitar and plug in, your body becomes part of the ground.

Touch your bridge, strings, etc, and the hum goes away. Lift your hands off…… hum.
 
No were thinking the same. The current (pun intended) U.K. regs mean that getting in proper electricians is usually at odds with old audio practice. Standing on a metal plate with shoes on doesn’t work unless the soles are conductive and you have sweaty feet. Think back to broadcast practice where you had a technical ground, and an electrical ground, and it would go very wron* when somebody plugged in a new bit of kit that had XLR pin 1 bonded to the case. I’m one of those who even had a 13A plug with a long cable with a croc clip on the end, and that would be a great way to add bonding and quieten a humming guitar amp.

My own experience with lifted grounds, taped back on the cable was UK band the Barron Knights. One night one of the guitars went silent, I could see the problem, the jack had fallen out! I crawled on stage on my stomach behind the amps. Bobbed up over the top of the amp and reached for the falls out metal jack. I was leaning on the radio mic receiver, and as I pushed the jack into the Fender amp, I got thrown across the stage. I still have the burn on my forearm. The amp was faulty and his guitar was live at 240V with the guitar working fine and hum free. This is why I’m very uptight over bodge up hum cures. Silence doesn’t mean safe.

Here electricians get very worked up by equi-potential zones, and those folk thumping in ground rods randomly in their garden studios make the real electricians cringe. Well, the newer qualified ones. I’ve always been fascinated by the fact that even wearing insulated trainers or shoes, your finger touching a string can have so much impact on noise. What is it? Our surface area, how moist our skin is, how fat we are? Is it something else? Capacitance, resistance, inductance? Touching the strings, then touching something grounded seems a rather risky thing to do. I worked with an old engineer in the tube days. He had no lining in his left trouser pocket. When he had a likelihood of touching something live, he’d put is hand in, squeeze his skin hard while prodding. He was convinced that this would be the exit path through his arm, not body if he got a shock. In right hand, across shoulders down arm rather than through his chest. I’ve no idea if that would have worked, but he did it one handed for all his working life.
 
Ok Rob, we's cool. The fact is that for at least the last 20 years or so, equipment of all sorts* has been very much safer than it was say, post WW2 . I have PAT checked 100s of pieces of kit over the years and never found one that had an earth leak (live to chassis) or lack of an adequate earth bond. That is not to say it could never happen but such faults are now extremely unlikely.

But no, do not ever 'tie' yourself to earth. In the very rare event that 'it'appen you need at least a chance to disconnect yourself! (V high resistance 'static straps' excepted)

The idea of class ll "double insulation" came about mainly I think because paradoxically it makes stuff SAFER! The fact was that electrical kit was sold without a mains plug and so there was always the potential (I can do it as well!) for the earth to be left off or worse, wired to live! The introduction of moulded plugs largely solved that one. Class ll does of course also save one third of the Copper in the mains cable, useful for thjings like vacs and hedge trimmers. Not so much for IEC sktd kit! As I mentioned, more and more active speakers are earth free, most using the fig 8 mains inlet. This is useful since one of THE main causes of ground loops was the monitors. Think back to "hi fi separates"? The big ole amplifier was almost always 3 wires but outboard gear, OR tape, cassette and tuners were/are almost always two core mains cable. Phono decks were a special case. The PU wiring was not earthed but usually not either the chassis but a lead was provided to connect it to the amp chassis and many amps provided a screw for the purpose. N.B. the earth cable was very light, far too thin to provide a serious safety earth.

*That is NOT to say that electrically unsafe gear does not still get here. Still caveat bloody emptor!

Dave.
 
ecc83 said:
It sounds very much as though you have an "earth free" system. This is becoming more common as more kit is made without an earth (class ll insulation) to combat ground loops. The problem is, things like guitars really need to be earthed. I suggest you take a wire from the earth pin on your mains socket (make SURE it is earth!) and connect that to the metal of the line 6 or Zoom, NOT both.

Dave.
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Can you explain what you mean by "earth free" exactly, and what connecting to the mains socket means? I apologize for my newbiness; as I said, I'm 12 years away from my last real studio work. I also taught myself at that time, so there's a ton I'm missing I'm sure.

Two things occurred to me last night: 1) I didn't try a different instrument; and 2) I thought that I could change the surge protector since the one I was using is older, so I swapped in a much newer and more robust one.
 
Bargarcs said:
Can you explain what you mean by "earth free" exactly, and what connecting to the mains socket means? I apologize for my newbiness; as I said, I'm 12 years away from my last real studio work. I also taught myself at that time, so there's a ton I'm missing I'm sure.

Two things occurred to me last night: 1) I didn't try a different instrument; and 2) I thought that I could change the surge protector since the one I was using is older, so I swapped in a much newer and more robust one.
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Hokay! The two devices you mentioned, the Line 6 and the Zoom are both powered from external mains 'lumps'. These are almost always without an earth connection these days, indeed they might even use a bi-pin fig 8 mains plug?
The consequence of all this is that the recording setup is 'floating' i.e. the audio screens are not grounded. This matters little in many cases but, as you have found, cause hum with a guitar.

I think you are based in the USA? I base that assumption on your mention of a "surge protector". We in UK rarely have need of such things, even quite large studio setup do not use power conditioners*

What you need to do I am sure is in effect ground the screen of the guitar cable (the guitar should have internal screening but that's another can!) This is best done by taking a single wire, anything will do, from a metal part of the Zoom or pod and connecting it to a known, good ground. The mains earth is usually the handiest but you can use a water pipe or the chassis of a desktop computer...MUST be plugged in! No need to be on.

*In some cases these can make hums worse especially the cheap filtered mains distribution strips.

Dave.
 
Earth free? Dave is trying to move to capacitor mics, terminology wise, but condenser is a think too engrained, but us Brits consciously have to remember to not say earth, but ground, if our US friends aren't to get confused. Virtually ALL power outlets here have grounds, and you won't get any 2 pin socketry anywhere. Just not allowed. This means that any US or European item brought into the UK needs and adaptor - and the majority of these are truly dire - too loose, the plugs fall out, too flimsy, the contacts bend, and too little metal so they overheat and melt. Dave mentioned the special mains plug that had a metal earth (ground) pin and no contacts for the line and neutral (line is our new word for live, by the way). The only thing it can do is allow a safety connection to the electrical infrastructure. We do have plenty of equipment that is double insulated - so no grounding needed or advised.

Unless you really know what you are doing - don't try this. If you have a decent meter that can measure current, measuring between grounds can be a real surprise. There should be no current flow whatsoever, but the reality is that so many devices leak and there is detectable current flowing in the wiring in a normal house. A little is considered OK, and probably unavoidable, but you also have safety devices that measure leakage current from an appliance to ground, and if more than 30mA or so, it cuts the power. With our audio equipment handling teeny amounts of electricity from mics and guitars, it's no wonder stray current gets in and hums!
 
Not pertinent to our friend Rob but RCCDs do not detect "earth current" (though we had them yonks ago in the sticks!) they work by sensing an imbalance between the line (live) wire current and the neutral. These will be nearly identical UNLESS some has been diverted via a body to earth (I 'm a brit!) Otherwise they would not trip out when folks go through the 2 core mains cable cutting the shrubbery!

We shall I think have to agree to disagree? I see no danger in the chap rigging a ground wire.

Dave.
 
Touching the Zoom should have exactly the same effect as touching the strings or bridge of the guitar. If touching the guitar doesn’t also reduce the hum, then that ground connection isn’t carrying through somewhere. I personally would probably start by swapping out whichever cables are between the guitar and the Zoom one at a time. Maybe one of those has a questionable shield connection. Then I’d look at the guitar itself. Is the bridge ground properly connected to the jack? If that’s all just fine, we’d start to expect a defect in one of the units. A dodgy solder joint or something.
 
I just got a Strymon Iridium. Pulling out my hollow body with P90s, it has a horrible buzz. After a few minutes, I put it away and pulled out some humbuckers... still buzzing. It was really bumming me, until I pulled out the manual and read this:

Noise Performance​

Iridium was designed as a an amp modeler solution in a pedal format that you can drop into any pedalboard. Like most other guitar pedals, it receives its ground connection via the 1/4″ output jacks. When listening to Iridium through the headphone output and using a wall adapter, there is no connection earth ground like there is with an amplifier. This causes some noise (hum) and is usually reduced when you ground the guitar by touching the strings. The adapter that is included with Iridium significantly reduces this hum when compared to similar parts. If an amplifier with an earth ground connection is available, then, the hum can be eliminated by connecting the LEFT or RIGHT OUT from Iridium to the input of the amplifier. The amplifier doesn’t need to be powered on for the ground to be provided. Power supplies like the Zuma and Ojai have much better filtering and isolation which will improve the noise performance.

Sure enough, I was using headphones and just the Iridium. I plugged the output into my amp, which was off and suddenly things went silent. No more buzz. I never tried that with my PODxt. It's something the OP might want to explore. It might be worth trying to run a wire from a ground spot on the R20, Line 6, or even from the metal ground of the guitar cable to a grounded spot.

That's apparently one of the issue with all the devices that use DC wall warts. There's no true ground point.
 
I did a video yesterday with mics I’ve used before, and there were four running to the zoom on batteries, always the quietest way. Got the files into the editor and one hissed like mad and another hummed? I never bother with headphones as I like to knowing in advance which sounds best, discovering it in the edit. I had to do the whole thing again. This time everything into the interface and in via cubase. No hum, no hiss. All cables used before, only new thing was two older mics condensers and two older dynamics all with phantom. Maybe leakage sapping the available power on batts? No idea? Hum just happens sometimes.
 
rob aylestone said:
I did a video yesterday with mics I’ve used before, and there were four running to the zoom on batteries, always the quietest way. Got the files into the editor and one hissed like mad and another hummed? I never bother with headphones as I like to knowing in advance which sounds best, discovering it in the edit. I had to do the whole thing again. This time everything into the interface and in via cubase. No hum, no hiss. All cables used before, only new thing was two older mics condensers and two older dynamics all with phantom. Maybe leakage sapping the available power on batts? No idea? Hum just happens sometimes.
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I bow to your vast experience Rob but mics and Zooms are not passive guitars! The instrument is unique in being a large area of signal wire (hopefully screened to some degree) with a source impedance of variable value, can be anywhere between 10k and 250k depending on the value and setting of the pots. The guitar then feeds a high impedance input which does not help!

Take a 'Strat' into the middle of a large field with a 100W battery amp and it will be as quiet as the proverbial grave (one assumes no overheads!) but as you get back to civilization you begin to be surrounded by a 50Hz electric field (60Hz of course across the pond) The various distortions and filtering that take place in the process of hum pickup make the hum more or less 'buzzy'.

Microphones are low impedance, 150-200 Ohms and the outputs of other kit should not exceed 100 Ohms these days, mics are also of course balanced.

Had the electric guitar been invented two decades ago it would surely have been designed differently? To be fair to the originators, they were plugging into what was effectively the arse end of a radio set and these were always earthed. Mr Christian and his fellows also did not want to generate 130dB SPLs!

Back over half a century when I was playing bass in a group many venues had either no earthed sockets or pretty dodgy 3 pin jobs and I carried a length of 4mm earth wire with a croc clip each end and I would go in search of a cold water tap!

Dave.
 
Bargarcs said:
Can you explain what you mean by "earth free" exactly, and what connecting to the mains socket means? I apologize for my newbiness; as I said, I'm 12 years away from my last real studio work. I also taught myself at that time, so there's a ton I'm missing I'm sure.

Two things occurred to me last night: 1) I didn't try a different instrument; and 2) I thought that I could change the surge protector since the one I was using is older, so I swapped in a much newer and more robust one.
Click to expand...
Earth = ground
 
The guitar single coil pickup 'hears' the PA feed, which also contains the same guitar and it feeds back - rather horribly. The only solution is to switch off the loop. Luckily music shows are loud enough it's usually OK to do that.
 
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