Mackie SWA1801 User Manual page 8

No sound
• Is the input LEVEL control for the input
source or the subwoofer turned all the
way down? Verify that all the volume
controls in the system are properly
adjusted.
• Is the signal source working (and making
union scale)? Make sure the connecting
cables are in good repair and securely
connected at both ends. Make sure the
output volume (gain) control on the
mixing console is turned up sufficiently
to drive the inputs of the speaker.
• Make sure the mixer does not have a
Mute on or a Processor loop engaged. If
you find something like this, make sure
the volume/gain is turned down before
disengaging the offending switch.
• Is the thermal protection circuit activated?
Make sure there is at least six inches of
free space behind the SWA1801.
Poor bass performance
• Check the polarity of the connections
between the mixer and the loudspeak-
ers. You may have your positive and
negative connections reversed at one
end of one cable, causing one loud-
speaker to be out-of-phase.
• Try switching the PHASE switch on the
rear panel. This affects the polarity
between the full-range speakers and the
SWA1801 and may improve the low-
frequency response.
Poor sound
• Is it loud and distorted? Make sure that
you're not overdriving a stage in the
signal chain. Verify that all level controls
are set properly.
• Is the input connector plugged com-
pletely into the jack? Be sure all
connections are secure. It's a good idea
to periodically clean all electrical
connections with a non-lubricating
electrical contact cleaner.
8
Noise
• Make sure all connections to the active
loudspeakers are good and sound.
• Make sure none of the signal cables are
routed near AC cables, power trans-
formers, or other EMI-inducing devices.
• Is there a light dimmer or other SCR-
based device on the same AC circuit as
the SWA1801? Use an AC line filter or
plug the SWA1801 into a different AC
circuit.
Hum
• Try disconnecting the cable connected
to the INPUT jack. If the noise disap-
pears, it could be a "ground loop,"
rather than a problem with the
SWA1801. Try some of the following
troubleshooting ideas:
• Use balanced connections throughout
your system for the best noise rejection.
• Whenever possible, plug all the audio
equipment's linecords into outlets which
share a common ground. The distance
between the outlets and the common
ground should be as short as possible.