SoundCraft SPIRIT POWERSTATION, User Manual

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WARNING
Do not obstruct air vents. Clean air filter at front of unit
regularly. (OK, so we know you probably won’t do this
regularly, but you’ve been warned...!)
19 POWER AMP LEVEL
The signals from the balanced Power Amp Inputs jacks
(normally the output from the Graphic Equaliser) are fed via
the POWER AMP LEVEL control to the integral stereo power
amplifier. Set the control at position 7 for normal operation.
20 SUB-SONIC FILTER
An 18dB/octave 40Hz SUB-SONIC FILTER may be switched
into the feed to the amplifier, and in most applications it is
recommended that this filter should be switched in. Using the
filter avoids potential loss of control in PA cabinets with reflex
ports when driven below their frequency range, and offers
some protection against damage from heavy ultra-bass
signals.
Switching the filter into circuit is almost always a good idea,
but may unnecessarily restrict the dynamic range of a system
with particularly wide-range PA cabinets, and should be
switched out if very low frequency rumbles are specifically
required and the speaker system has the capability. The filter
also allows you to use your LF boost to warm up the bottom
end of your mix without the usual problems of bass
distortion.
Loudspeaker Output Terminals
The power amplifier output is available on standard dual
banana terminals and ’speakon’ connectors on the rear of the
mixer, above the power switch.
Minimum recommended load impedance is 4
Ω
but the
amplifier guards itself against damaging overload, switching
in the protection systems when necessary. While this will
maintain safe operating limits, the result will be serious
distortion and a very unmusical sound. Always follow the
load recommendations where possible.
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