55
INITIAL setting up
You will probably use your
SPIRIT FOLIO LITE
with a wide range of different types of sound source, and these will be at
varying signal levels. The mic amp has been designed with a particularly wide gain range, but it is important to set the
TRIM control correctly to give the best performance. If the input level is too high the signal will distort as it overloads the
channel and causes clipping. If it is too low the level of any background hiss will be more noticeable and you may not be
able to get enough signal level to the output of the mixer. This is illustrated in the diagram below.
Set up the individual mono input channels as follows:
o
Plug in the chosen source (usually the MIC input for
mics and the LINE input for anything else). Plug in
phantom powered mics before switching the
phantom power on.
o
Set the rotary Mix Fader on the Master section fully
anticlockwise. Press the PFL switch on the Master
section to route PFL to the monitor and meters.
o
Provide the chosen source with a typical signal level
and press the PFL button by the fader. The level of
signal will be shown on the Bargraph Meters.
o
Adjust the input TRIM until the meter is just reaching
the amber LED (0dB) at a typical maximum source
level with a steady signal. If the source signal is rich
in high-level transients (e.g. drums) a rather higher
meter reading of +6/+9 will be needed to achieve
an equivalent average level. This leaves enough
headroom to cope with peaks in the signal without
distortion.
o
Adjust each mono input channel in the same way.
o
If you find that you cannot set a reasonable level within the range of the TRIM control when using a MIC input, try the
LINE input instead.
The Stereo inputs can be set up in a similar way. Start with the GAIN control anticlockwise, which will suit inputs from
professional equipment with a +4dBu output. A higher GAIN setting will be needed for semiprofessional sources which
typically have -10dBV output level.
You will now have initial settings for each of the input sources and are ready to start building a mix.
o
Connect your power amplifiers and speakers and set the gain of the amplifiers to about 70%. Set the Master Fader
fully clockwise, listening carefully for any hint of feedback or overload. You may find that the input fader settings will
need to be edged back slightly as the mix is built up.
o
Listen carefully for the characteristic sound of `feedback. If you cannot achieve a satisfactory input level setting
without feedback, adjust microphone and speaker positions and try again.
Careful microphone placement and the choice of a suitable type of microphone is essential for successful PA use. The aim
should be to place the microphone as close as possible to the source, to cut out unwanted surrounding sounds. This allows
a lower gain setting on the mixer and helps to avoid feedback. You will also find that a well-placed microphone will not
need any appreciable equalisation.
If the signal level is too low it may be masked
by the noise.
Signal
Noise
If the signal level is too high, clipping distortion
may occur.
Clipped
Signal
Noise
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