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All studios, big or small can have problems with buzzes and hums. These
types of problems can quickly make the product put out by the studio unprofessional or
even unusable. These buzzes and hums come primarily from television
broadcast signals that get into audio wires and equipment. The interconnecting wires
for the equipment have a shield that is supposed to be connected to "ground."
The "connection to ground" literally means that the shield is connected to the
earth we walk on. This ground is "zero volts." The idea is that a
broadcast signal (or other stray signal) can induce buzz in the shield which "shorts
out" the buzz. Home studios and professional studios alike get into trouble
when grounds or shields are not used or not used properly.
The professional studio can spend a lot of money and effort getting
"grounding" correct, but to do a half-way-decent job that works in 99% of the
home studios is relatively easy. |
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Step 1: Establish Ground |
| The 3rd pin of a common household outlet is supposed to be
"grounded." This ground is good enough for most small studios. Sometimes
the outlet is not wired correctly. To establish that you have a ground go to Radio Shack
and purchase an outlet tester (about $15) and plug it in. The instructions will tell
you what lights are supposed to light if your outlet is correct. |
| If you have an older 2 prong outlet, buy a grounding adapter
(about $1.00) and connect the green wire or green tab under the screw that holds on the
plate. Then test the outlet. |
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Step 2 - Establish ONE Ground Source |
| In theory, any of the outlets in a building are supposed to have
"0" volts on their ground pins. NOT SO. Most outlets have a small
voltage (1/2 to 1 volt). So it is important that the SAME ground be used for all of
your equipment, including instrument amplifiers that are going to be used. If
different outlets are used for some of the equipment the, difference between the voltage
on the ground pins of the two outlets can cause hum. |
| Use one outlet and a bunch of multi-outlet strips (these are
about $7 at your building supply company). Make sure everything goes back to the
same outlet. Your equipment does not draw a lot of power and 99.9% of the time you
won't be tripping circuit breakers because of this. Try to choose an outlet that
doesn't have motor-driven appliances likes washers on the same circuit. |
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Step 3 - Check For Broken Wires |
A piece of equipment can work with a broken ground wire but
become an "antenna" for hum & buzz.
| The third pin of equipment power cords connects the case of the
equipment to ground. One of the pins of the audio cables carries the shield. |
| You can make a tester to check your cables by taking apart a
flashlight (about $1) and taping some scrap wire to the battery & bulb (as shown
in the diagram). Connect one wire to one pin of the audio connector at one end of
the cable and the other wire to the same pin at the other end. If the light lights,
your connection is good. For the 3rd pin on the power plug, connect the second end
of your tester to the metal of the case on your equipment. |
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