Ashly Parametric Equalizers SC-63 - Manual (Page 12)

ITEM; Front System Speaker or Room Resonance Problems and Feedback Control
Once you become familiar with the controls on your parametric, you will find
it much easier to get the desired results from your system. Use the narrow
band step by step setup instructions on page 8 as a guide to get you started,
NOTE; The maximum volume of your monitors and front system before feedback
should be determined if the steps on page 8 are followed. If you are still
not satisfied, here are some suggestions that might help:
Place all main system speakers and monitors such that they do not "see"
any microphones that are to be fed to them.
Keep all guitar and keyboard stage amps away from vocal microphones.
Keep your stage volume as low as possible so your sound person has
something to work with out front.
Work vocal microphones as close as possible.
When you can't hear yourself, have everyone else turn down rather than
you turning up. You have already determined the maximum volume of your
PA system, and if your fellow band members feel they can't turn down any
more, collect donations to pay for upgrading your present system, ie;
separate mixes for monitor speakers, more directional microphones, better
speakers, etc.
ITEM; Shaping The Overall Sound Of Your System To Improve Response
Many PA systems use several bands of graphic equalization for frequency
response adjustment. For many situations, one band of parametric equalization
could achieve better results.
Say, for example, that the response of a high powered horn and driver that you
are using has a noticeable 3 dB rise in the frequency area from around 1,100
Hz to 3.500 Hz. If you attempted to correct your problem with a 1/3 octave
graphic equalizer, you would need to move five separate controls. Visually,
what looks like a nice smooth curve on the front controls of a graphic, turns
out to be a very bumpy curve as illustrated below.
This occurs because each control has a fixed bandwidth. Combinations of
filters can not generate the smooth curve of one variable filter.
Using one band of parametric with the frequency control set in the middle of
the problem area (approx. 2,200 Hz), the bandwidth control at 2 octaves, and
the amplitude control set at -3 dB, you get a frequency response plot that
will more accurately correct the problem.
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