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Operations Section
Setting Input levels:
Now that you've hooked up the MM-1, it's time to set
the levels of your equipment. This is critical for getting
the best sound: the best mixer in the world will sound
noisy if its gaim are set incorrectly. The goal is to get as
"hot" a signal going as possible, without distorting the
mixer itself.
1. Turn the level controls on your instrument (don't
forget expression pedals) all the way up.
2. Turn the INPUT FADER and MASTER FADER con
trols on the MM-1 all the way down, or mute the chan
nels.
3. Play the instrument, watching the LEVEL LEDS for
that channel. Although you'll hear no sound, the green
LED on the channel input meter should go on as you
play.
4. Turn the TRIM control so that the yellow LED is on
while you're playing. You may have to adjust the trims
again for different patches, etc., and if you increase the
EO settings.
You may choose to increase it so that on the loudest
peaks,' the red L ED flashes occasionally. (When the red
LED comes on, you have only 3 dB before the mixer
electronics will clip or distort), Setting the trim of each
channel this way will give you the best signal-to-noise
ratio. On the other hand, lower trim settings give you
more headroom, so the MM-1 won't distort if you
boost the EO or if the instrument suddenly gets louder.
When all the channels are playing at once, you may need
to lower the trims still more.
Setting Output Levels:
5.
Turn the volume control(s) of your power amplifier
all th e way down.
6. Now, unmute the channels and bring all the CHAN
NEL FADERS to their nominal positions (the shaded
area between 7 and 8).
7. While playing, slowly bring up the L!R MASTER
FADERS until the L!R meters read +6 on the loudest
peaks, and the average is around 0 VU (the dividing line
between the green and red section of the meter).
8.
While playing, slowly bring up the volume controls on
your power amp. Adjust the mix on the channel faders,
making sure that you increase or decrease the L!R
MASTERS so that the MM-1 meters read a strong level.
Increase the power amp volume control until you get the
level you want.
This is the best way to get the best signal-to-noise ratio
from you r system. I n most cases: keep everyting as "hot"
as possible, and set the power amp controls to low sensi
tivity to get the overall level you want. If you make the
mistake of running the faders of the MM-1 at a low level,
and leaving the power amp wide open, all you are doing
is amplifiying the residual noise of the mixer.
I n some cases (su ch as Ex ample #2 above, into a gu itar
amp), the MM-1 output could be too loud for the ampli
fier it's connected to, causing its input stage to distort.
In this case, feed the power amp from the phono (RCA)
outputs; they are 10 dB softer than the 1/4" phone out
puts (about half as loud).
Clipping Output level: The MM-1 has a maximum out
put from the phone jacks of +13 dBu (3.5 volts). Most
power amps deliver their rated power with an input
of 0 dBV (1 volt) or less; and usually you don't run your
power amp at full output all the time. If the volume con
trols of your power amplifier are marked with attenua
tion numbers, try setting them to the "-20 dB" position
to start. This means that even when the MM-1 is putting
out 3.5 volts, the amp will only "hear" 1 volt. The MM-1
operates at the level farthest from the noise floor, and
your amp runs at its nominal operating level. CAUTION:
it is possible to blow speakers or damage the amplifier
itself if the system is overdriven. Use care when setting
levels, making connections, and tu rning the system on.
Setting levels: To Effect Devices
Effect devices are typically the noisiest elements of a
system, but with proper level setting you won't hear the
noise. Again, the principle is to have as loud a signal as
possible going into the effect device, and turn down the
effect
return
level when you want less effect.
Most effect devices have some kind of input meter
sometimes a single LED that changes color to red when
the distortion point is reached. They mayor may not
have their own input and output level controls; some
times there is a level switch. You have to set these pro
perly to get the best signal-to-noise ratio from your
system.
1. Go through the "Setting Input Levels" and "Setting
Output Levels" procedures to set the trim and fader
levels of the mixer properly if you haven't already.
2. Set the EFF 1/2 and EFF 3/4 controls in the channels
to their maximum settings (full clockwise for Effect 2
and Effect 4, full counter-clockwise for Effect 1 and
Effect 3).
3. Set the EFFECT SEND MASTERS to the "2 o'clock"
position.
4. While playing the instruments, slowly increase the
input control of the effect unit. Stop when the effect
device's meter or clip light warns of distortion.
If the effect unit has an input level switch (for example
"+4/-20"), set it to the -20dB (most sensitive) position.
Change it to +4 (least sensitive) only if you can't get a
non-clipping level by slightly turning down the EFFECT
SEND MASTER of the MM-1.
Setting levels: From Effect Devices
Now that we know your effect device IS exercIsing its
full dynamic range - the input signal is not buried in the
noise floor, or clipping the device - we can set the out
put level of the effect device (if it has one). Here, noise
is less of a problem: we're aiming for maximum control.
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