13
You’re now ready to establish the correct gain structure—the key to getting the
best performance from the SD8, or from any mixer, for that matter. This is a
simple procedure that ensures optimum input and output levels so that no
unnecessary noise (caused by too low a signal) or overload distortion (caused by
too high a signal) is created. Here’s a step-by-step description of how to do so:
a. With all connections made (as described above) but with the power off, start
by setting all channel Level controls fully counterclockwise (to their “
∞
” position),
and then set the Main Level knob to its “0” position.
b. Set all channel input Trim knobs to their fully counterclockwise (-6) position.
c. Set all channel equalizer knobs to their center detent “0” positions and set the
ten-band graphic master equalizer completely flat (all sliders at their center
detent “0” positions).
d. Set all channel Aux 1 / Monitor send knobs and the main section Aux return
Level knob to their fully counterclockwise (“
∞
”) position. Set all channel
DSP / Aux 2 knobs to their center detented 12 o’clock position and set the main
section DSP Mix Level knob to its fully counterclockwise (“
∞
”) position.
e. Turn on all devices connected to channel line inputs and Aux returns and set
their level controls to unity gain or, if there is no unity gain indicated on their
output control, to maximum. If you’ve got outboard effects processors connected
to the Aux returns, make sure they are sending completely “wet” (processed)
signal, with no “dry” (unprocessed) signal mixed in.
f. If condenser microphones are connected to the SD8, turn on the Phantom
switch.* Finally, turn on the SD8’s main power.
g. Play an instrument connected to one of the SD8’s line inputs** and, while
doing so, raise the corresponding channel Level control to the “0” position. You
should see the segment meter begin to move—adjust the input Trim control for
that channel so that the “0” segment lights frequently and the “+3” segment lights
only occasionally. The Peak LED for that channel should not flash at even the
highest level input signals. If the incoming signal seems too hot even with the
input channel Trim all the way at its minimum (-6) setting, you may need to lower
the output level of the instrument, though this will rarely occur. Conversely, if the
signal is too low even with the input channel trim all the way up, something’s
definitely wrong: in all likelihood, the connecting audio cable is faulty.
h. Once you’ve set the optimum level in step (g) above, continue playing the
instrument and slowly raise the main Level knob until you reach the desired
listening level.
i. Repeat step (g) above for each instrument connected to the SD8 channel line
inputs.
* CAUTION: Before turning phantom power on, be sure to verify that all
connected mic(s) and/or active DI boxes require 48 volts. Also, disconnect all
other signal sources (such as passive DI boxes) from the XLR mic jacks.
** If you’re using an instrument such as electric guitar or bass, connect it to the
SD8 with a direct injection box to ensure correct impedance.
Setting the Correct Gain Structure
