This technical article deals with common grounding issues with equipment used by musicians.
Not So Silent, But Deadly
It’s important because there are documented cases of people getting hurt, even killed, just because they didn’t know they should be plugging their guitar amp into a certain circuit. Maybe they weren’t following instructions, or worse, a technician didn’t use safe practices.
If you have hum you can hear, that can be a problem; if you touch a microphone while holding a guitar and get a shock, that’s a serious problem.
While the issues can seem complicated, here are some simple troubleshooting related points.
Real, Safe Fixes For Hum And Buzz
First, you’ll want to plug everything on stage (and everything being used to create your music, mixing boards, pedals and effects) into the same electrical circuit. The practicality of this is one reason why the concept is commonly violated in larger setups and at larger venues, when they run out of plugs and get creative!
For purposes of safety, managing this is most important with amplified instruments (including microphones) that have metal components, where electricity could come through the housing or casing (not so much pianos), including guitar strings, which are connected by a wire to the guitar’s cable input jack. Both guitars and microphones are almost always part of the electricity pathway.
Try This At Home
If you’re a collector and have a lot of amplifiers at home, it’s well worth the trouble, energy and cost to seek assistance from an electrician or someone with expertise to fix any grounding problems, worth as much as the gear itself.
The specific goal is to have everything on the same ground. This generally means everything should be on the same circuit. In a home environment you could install a grounding rod just for your music room. Grounding rods are easier to install than you might imagine; a hammer, a rod, a few hits and you’ve got copper down six feet into the ground.
What You Need To Know
When two devices are grounded separately from each other, the grounding paths may have different efficiencies. The difference in efficiency (resistance) results in unwanted electricity being available in one of the circuits.
If one of the devices is a mixing board, and the other is a guitar amplifier, and one of your hands is touching a guitar string and your mouth touches the microphone, you are effectively creating a ground that’s sufficient to take any lingering electricity through your body to the earth.
Be extra careful if you are barefoot!
How much electricity there is, depends on the different resistances – what you need to know is, it’s not always just a small shock!
Sound Check Time
Once you’ve decided where things are going to be plugged in, take everything that isn’t used for your music off of the circuit. A lamp uses as much electricity as a guitar amplifier. You won’t have plugs to play with, so take everything that isn’t part of the PA and plug them in elsewhere.
What kind of lighting do you have other than lamps? Certain types of lights use a lot more electricity, and lights with dimmers often cause buzzing problems in audio systems. Turn ’em off!
Use a circuit that doesn’t have any large electricity-using devices on it, which could be defined as things with electric motors and heaters and air conditioners.
While your guitar amp is on, turn your television (if there is one nearby) on and off, even if it’s on a different circuit. Computers and televisions operate at frequencies (in other words they vibrate) and so can talk to other appliances right through the air, and that may be undesirable. Computer USB ports can be poorly shielded and cause intermittent noise.
Look at your cabling (yes, that cabling you’ve been stuffing under area rugs and trying not to trip over) – separate power cables from anything audio-related. If power cables and audio cables need to cross each other, do it at a 90 angle. If possible, tape down cables; keep them organized; randomness is not your friend.
Never lift grounds. This is a technical term and a common practice, but it’s dangerous. People have died. If you would like to know more about this, it’s a topic you can read about nearly endlessly.
All components – everything – should be grounded; this is critical. Battery-powered devices, which are becoming more popular, are beyond the scope of this, but turn them off when troubleshooting.
Use quality cabling; a compromised or cheaply-made cable will haunt you. If you have a larger room and your mixer is at the far end, with the performance area at the other, you’ll still want your mixer plugged in at the end of the room where everything else is; no exceptions!
If you have too much extension cord, don’t coil it; an electrical coil can cause a fire (and hum).
Let’s Get Back To Playing!
Finally, if you’re not getting shocks anywhere, but you touch your guitar strings and the humming goes away, check that your amplifier is properly grounded, try different circuits (just with the amp), and try turning anything else off, especially television sets. What you DO know is your guitar IS properly grounded (the problem is elsewhere), because your body is completing the grounding circuit!
Food for thought!
Be safe and have fun!