SoundCraft EFX User Manual page 20

USING YOUR EFX OR EPM CONSOLE
The final 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 be-
cause 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 dia-
grams 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 in-
puts.
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 amplifier levels
to about 70%.
•
Provide a typical performance level signal and press the PFL button on
the first 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 first red LED at a typical maximum source level.
This allows sufficient 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 micro-
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Soundcraft EFX/EPM User Guide Issue 1110
phone 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.
Note:
The initial settings should only be regarded as a starting point for your mix.
It is important to remember that many factors affect the sound during a
live performance, for instance the size of the audience!
You are now ready to start building the mix and this should be done pro-
gressively, listening carefully for each component in the mix and watching
the meters for any hint of overload. If this occurs, back off the appropriate
Channel Fader slightly until the level is out of the red segments, or adjust
the Master Faders.
Remember that the mixer is a mixer, not an amplifier. Increasing the
overall level is the job of the amplifier, and if it is impossible to provide
adequate level, it is probable that the amplifier is too small for the ap-
plication. Choose your amplifier carefully, and do not try to compensate
for lack of power by using the mixer to increase output level.
Note:
The level of any source signal in the final output is affected by many fac-
tors, principally the Input Gain control, Channel Fader and Mix Faders. You
should try to use only as much microphone gain as required to achieve a
good balance between signals, with the faders set as described above.
If the input gain is set too high, the channel fader will need to be pulled
down too far in compensation to leave enough travel for successful mixing
and there is a greater risk of feedback because small fader movements will
have a very significant effect on output level. Also there will be a chance
of distortion as the signal overloads the channel and causes clipping.
If the gain is set too low, you will not find enough gain on the faders to
bring the signal up to an adequate level, and backgound hiss will be
more noticeable.
This is illustrated below:
Soundcraft EFX/EPM User Guide Issue 1110
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