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Troubleshooting A Noisy PA System
When your band plays in
different locations on a regular basis, noise in your
P.A. system is a very common, and sometimes a very
difficult problem to solve. Noise comes from many
sources. Some of the most common ones are:
1. Poor cables on the
2. Fluorescent lights.
4. Poor design, particularly
shielding and location of the mixer and power amps power
5. Poor A/C wiring in the
location where the P.A. is being used.
6. Radio stations or other
transmitters in the area.
7. Large motors close to the
8. Grounding problems, when
using equipment manufactured by different companies.
9. Noise in the input
signal, especially guitar pickups.
10. Magnetic fields induced
by other nearby components like air conditioners.
to turn down your level sliders before you attempt to
plug or unplug any source that is connected to your
system, or you may produce damaging pops or clicks that
can take out speakers.
Most of these system problems can be reduced or even
eliminated by using high quality cables and balanced
check for the source of the noise, unplug all inputs at
the mixer input jacks and listen for noise. Any noise
that has now disappearedis definitely coming from
something that you are plugging into the input of the
mixer and not from the P.A. itself. If this is the case,
start plugging the sources back into the mixer, one by
one. Listen for noise changes. When you hear noise when
you plug something in, you now know that this device is
a problem and you should take steps to eliminate the
problem with the device. Some sources, especially
keyboards and guitars, are noisy and cannot be improved
are a few tips to help with input noise problems:
Remember, some hiss is
normal, and occurs when an input is at a high level, or
all the way up.
Reduce the length of the cables.
2. Wherever possible, use
balanced sources. Some mixers have both balanced and
unbalanced outputs on their products. If they do, change
to balanced. Use of a balanced cable will even improve
noise in unbalanced sources.
3. Use direct boxes where
possible for instruments being plugged into the mixer.
This isolates the signal, converts any high impedance
instruments to be balanced, low impedance, and allows
you to "lift" the grounds on these devices. "Lifting"
the ground will help eliminate MANY sources of
4. Change your cables to
higher quality ones with a high degree of shielding.
5. Make sure the input
cables are not lying too close to a transformer, motor,
amplifier or other source of magnetic radiation.
6. Plugging the
components of a P.A. system into different electrical
outlets can sometimes cause problems. Where ever
possible, try to connect all parts of the P.A. into the
same circuit, even if you have to run extension cords to
7. Turn any lights on
dimmers off, or if this is not possible, turn them fully
If the noise does not disappear or reduce significantly
when you disconnect all inputs, then the problem lies
somewhere else in the system. Take a step-by-step
approach to determine where the problem lies. Try to
"cut the system in half" when trouble shooting.
First start with the
mixer. Turn all outputs to zero. If the noise disappears
then the problem is in the mixer; otherwise it is after
the mixer. If it is in the mixer, try removing all
effects devices such as delays or reverbs, if there are
any, and try again. Keep going through the process of
eliminating components until you find the problem,
keeping in mind that many noise problems are as a result
of inferior or defective cables.
Eventually you will
locate the problem, and the suggestions mentioned above
should help in most cases.
About The Author: Richard
Pace is a author and studio engineer for many musicians. He is a
consistant "problem solver" and is know for his knowledge of
noise and feedback resolution. See some of his other works at
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