AudioControl SA-3051, Руководство по эксплуатации

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SA-3051/SA-3052 Operation Manual
• Do flatten peaks.
• Do remove shallow, wide bandwidth holes.
• Do not remove large holes of any bandwidth.
• Beware of adding large amounts of boost at low frequencies. Unless you have infinite amplifier power
and speakers capable of moving infinitely far, this is an invitation to amplifier clipping or speaker de -
struction.
• Remember that 3 dB of boost requires twice the amplifier power at that frequency.
Fold Back Monitor Equalization
Fold Back monitor speakers are a difficult proposition at best. The SA-3051/SA-3052 can help by telling
you exactly what frequency is ringing when the monitors feed back. Even if you only have an octave band
equalizer, the one-third octave display of the SA-3051/SA-3052 tells you if the offending frequency is
right on a band center, or if it is in-between.
There are two schools of thought presently. We'll simply present them both. School A probably evolved
from folks who didn't have a real-time analyzer. School A is popularly known as feedback tuning. School
B involves using pink noise to flatten out the frequency response, followed by feedback tuning.
Regardless of which method you use, remember that when a person steps in front of the microphone, their
face acts as a reflector and reflects energy from the monitor speaker back into the microphone. This will
change your tuning on the monitor equalizer.
Feedback tuning
What could be simpler? Make the sound system feed back, find the feedback frequency on the equalizer
and notch it out slightly. Repeat as necessary. One-third octave equalizers make this a tricky proposition
to say the least.
Before the SA-3051/SA-3052, the process of finding the feedback frequency on the equalizer was the
hard part. Some of the techniques used are: guess-and-by-gosh; using a frequency counter; zero-beat with
an oscillator; and relating the feedback pitch to the nearest musical pitch, then converting the musical
pitch to a numerical frequency (easier than it sounds).
With the SA-3051/SA-3052 connected across the mixer output (you can use the microphone instead),
bring the system slowly into feedback. Watch the display. When the system starts feeding back, reduce the
gain. The offending frequency is the last one to decay off of the screen. This even works during perfor-
mance. Now find the frequency on your equalizer and dial in some cut at that frequency. Once more, bring
the system slowly into feedback. Repeat the squeal and notch technique until two or more frequencies
feed back simultaneously.
Pink noise equalization and feedback tuning
The procedure for School B is very similar, except you first use pink noise and the SA-3051/SA-3052’s
calibrated microphone to equalize the monitors. Then revert to School A's technique to find out where the
system wants to squeal.
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