User Manual

60
Soundcraft Si Expression User Guide V1.0 0213
USING YOUR Si EXPRESSION CONSOLE
The nal output from your sound system can only ever be as good as the weakest
link in the chain, and especially important is the quality of the source signal because
this is the starting point of the chain. Just as you need to become familiar with the
control functions of your mixer, so you must recognise the importance of correct
choice of inputs, microphone placement and input channel settings. However, no
amount of careful setting up can take account of the spontaneity and unpredictability
of live performance. The mixer must be set up to provide “spare” control range to
compensate for changing microphone position and the absorption effect of a large
audience (different acoustic characteristics from soundcheck to show).
MICROPHONE PLACEMENT
Careful microphone placement and the choice of a suitable type of microphone for
the job is one of the essentials of successful sound reinforcement. The diagrams
on the left show the different pick-up patterns for the most common types of
microphone. Cardioid microphones are most sensitive to sound coming from in
front, and hypercardioid microphones offer even greater directivity, with a small
amount of pickup behind the microphone. These types are ideal for recording
vocalists or instruments, where rejection of unwanted sounds and elimination of
feedback is important. The aim should be to place the microphone as close as
physically possible to the source, to cut out unwanted surrounding sounds, allow
a lower gain setting on the mixer and avoid feedback. Also a well chosen and well
placed microphone should not need any appreciable equalisation.
There are no exact rules, let your ears be the judge. In the end, the position that
gives the desired effect is the correct position!
INITIAL SETUP
Once you have connected up your system (see the sections on connection and
wiring earlier in this manual for guidance) you are ready to set initial positions for
the controls on your mixer.
Set up individual input channel as follows:
• Connect your sources (microphone, keyboard etc.) to the required inputs.
WARNING: Phantom powered mics should be connected before the +48V
is switched on. Ensure the PA system is OFF when switching phantom
power on or off.
• Set Master faders at 0, input faders at 0, and set power amplier levels to
about 70%.
• Provide a typical performance level signal and press the PFL button on the
rst channel, monitoring the level on the bargraph meters.
• Adjust the input gain until the meter display is in the amber section, with
occasional peaks to the rst red LED at a typical maximum source level.
This allows sufcient headroom to accommodate peaks and establishes the
maximum level for normal operation (but see note below).
• Repeat this procedure on other channels as required. As more channels
are added to the mix, the meters may move into the red section. Adjust the
overall level using the Master Faders if necessary.
• Listen carefully for the characteristic sound of “feedback”. If you cannot
achieve satisfactory input level setting without feedback, check microphone
and speaker placement and repeat the exercise. If feedback persists, it may
be necessary to use a Graphic Equaliser to reduce the system response at
particular resonant frequencies.