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MASTER FADER
As its name
implies, the master fader is an overall
level control.
It adjusts the overall output level for
the STEREO
and HEADPHONE
outputs, but not
for the LINE OUTputs.
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GRAPHIC EQUALIZER
The
MM30's
built-in
graphic
equalizer
provides
seven individual bands of equalization control. The
control
bands are centered at 60, 150, 400, 1000,
2400, 6000 and 15000 Hz. Each of these frequency
bands can be boosted or cut by up to 12 dB (+12
dB). The equalizer is ''graphic'' because the boost/
cut controls for each band are linear types, and their
setting gives you a "graphic" representation of the
overall equalization curve.
The things you can do with the graphic equalizer are
virtually
unlimited,
but
basically
it gives
you
tremendous
sound
''shaping'' control. Just a small
amount
of boost or cut in any band can dramati-
cally alter the sound of your program. Although it's
a lot of fun to create "wild" sounds with heavy EQ,
as a general
rule it's
a good
idea to avoid over-
equalization.
Always
start
with
the
equalizer
controls flat--so your ears have a reference--then try
boosting or cutting the band that is most likely to
need EQ (you'll get a feel for this with experience)
a little at a time. You may have to EQ more than
one
band
to
get
the
desired
sound.
Always
remember,
though,
that your
ears
have
a short
memory!
That
is, they quickly
get used to the
equalized sound, So if you're not sure that you have
the right sound, try resetting the equalizer controls
to all flat, listen, and re-equalize. Another use of the
graphic equalizer is in reducing acoustic feedback. If
you
get a feedback
how!
or
whine
when
using
microphone
inputs,
first try pointing
the makes
away
from
the
monitor
speakers,
then
if the
problem
persists, use the equalizer. Try cutting the
bands in the frequency range where you think the
feedback
is occuring
all the way--one
by one, of
course--until
you
find
the
band
that
stops
the
feedback. Then raise the control for that band just
until the feedback begins again, then lower it just
until the feedback stops. You have thus eliminated
the feedback
with the minimum
possible effect on
the response of the rest of the program.
EQ FREQUENCY RESPONSE
RESPONSE
(dB)
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LED PEAK METERS
In the input fader section we discussed the impor-
tance of proper fader setting in order to achieve the
best possible sound quality. The MM30's LED peak
meters
are a tremendous
aid in setting optimum
fader levels.
Two meters are provided--one each for the left and
right stereo output channels. Each meter consists of
7 LED segments that light in sequence to show the
peak signal level for the respective channel. Meter
display
range
is from
—20 dB to +6 dB. Levels
below
О dB
are
displayed
in green, while
levels
higher than O dB are displayed in red. Watching the
meters you can easily see when signal levels are high
enough to present a danger of overload distortion--
the red LEDs will be lit most of the time. On the
other hand, if the meters almost never reach the 0
dB level, then the overall program level is too low.
Once the optimum program level has been set, peaks
in the program will cause the red LEDs to flicker
occasionally, and most of the green LEDs will stay
lit most
of the time.
This applies
mainly
to the
average music program. Some types of program will
have a completely
different effect on the meters,
requiring appropriate
level adjustment.
In general,
though, it is a good idea to avoid a lot of peaks in
the red region. Also remember that when only one
instrument is playing the level might look quite low
on the meters, but when instruments connected to
all four inputs start to play their individual levels
can add up to overload
distortion. So check the
meters when the entire program is playing.
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