Crest Audio CC 1800 - Manual (Page 23)

p. 7
features overview 3
front panel
switches and controls
1 AC Power Switch/Circuit Breaker
The CC Series amplifiers have a combination AC switch/circuit breaker
on the front panel. If the switch shuts off during normal use, push it
back to the ON position once. If it will not stay on, the amplifier needs
servicing.
2 Input Attenuators
Whenever possible, set the attenuators fully clockwise to maintain
optimum system headroom. The input attenuator controls (one for
channel A, one for channel B) located at the front panel adjust gain for
their respective amplifier channels in all modes. See the specifications
at the end of this manual for standard voltage gain and input sensitivity
information.
indicators
CC Series amplifiers feature four front panel LED indicators per channel: ACL ™
(Automatic Clip Limiting), Signal, Temp, and Active. These LED indicators inform
the user of each channel’s operating status and warn of possible abnormal condi-
tions.
3 ACL LED
A channel’s ACL LED will light at the onset of clipping. If the LED’s are
flashing quickly and intermittently, the channel is just at the clip
threshold, while a steady, bright glow means the amp is clip limiting,
or reducing gain to prevent severely clipped waveforms reaching
the loudspeakers. See the Automatic Clip Limiting section for more
information. During initial power up the ACL LED will light indicating
that the AUTORAMP ™ gain reduction circuitry is activated. This will
prevent sudden signal bursts when the speaker relays are closed.
4 Signal LED
This LED lights when its channel produces an output signal of about
4 volts RMS or more (0.1 volt or more at the input, with 0 dB
attenuation and standard x40 voltage gain). It is useful in determining
whether a signal is reaching and being amplified by the amplifier.
5 Temp LED
The Temp LED lights to indicate that the channel’s output relay is open,
disconnecting the speaker(s) due to an overheating condition. Once the
channel temperature has returned to safe operating conditions the LED
will turn off, the channel's output relay will close, and the speaker(s) will be
reconnected.
6 Active LED
The Active LED indicates that its channel’s output relay is closed and the
channel is operational. It lights under normal operation and remains on even
when the channel is in Automatic Clip Limiting or ACL gain reduction. These
are protection features which leave the output relay closed. If the Active LED
goes off, there is no signal at the output connectors.
The power only breaks
one side of the AC mains.
Hazardous energy may be
present in the enclosure
when the power switch is in
the off position.
a
When operating in the bridged
mode, both attenuators must
be in the same position so the
speaker load will be equally
shared between the channels.
See the section on Bridged
Mono Operation for more
information and precautions.
a