Operating Your Amplifier; Front Panel Controls And Indicators; Notes And Switching On - HK Audio CPQ 10 Manuel

3. Operating Your Amplifier

3.1 Front Panel Controls and Indicators

7 8
Bridge A-B A/P
6 PRC A PRC B
-24 -16 -6 -3 Lim -24 -16 -6 -3 Lim
OCM
A -6 B -6
-4
-12 -12
-2
-20 -20
0 0
- dB - dB
Link
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1 Power Switch: This single pole switch turns the amplifier fully off (but
does NOT isolate it from the mains supply).
2 Power LED: This indicates when the amplifier is active. This does
NOT indicate the presence of a mains supply when the power switch
is OFF.
3 Signal Meter and OCM indicators: These LED bar graphs show
instantaneous level on each channel to indicate proximity to the limiter
threshold. Note that if the PRC system is in operation on any channel,
this will affect the readout shown on the respective meter. The red
LED in the meter will illuminate when the limiter threshold has been
reached and limiting is occurring. The output current monitor (OCM)
may activate to limit the output current of the amplifier channel - this
can occur even if the amplifier has not reached clipping point.
The OCM indicator can operate independently of the bar graph meter.
Typical conditions that may trigger the OCM circuitry would be very
low load impedance, or high subsonic or VHF levels.
4 Attenuation Controls: These are analogue controls allowing precise
level settings. Note that in bridged (mono) mode some controls may
be inactive.
5 Link LED: This indicates if the channel is linked to its immediate
neighbour. If this is illuminated, the attenuation control of the channel
to the immediate right will not function as both channels are being fed
from the left hand channel. The link switches are on the rear panel —
see chapter 3.3 for details.
6 PRC LED: This illuminates if the Power Reduction Control has been
enabled on the respective channel. PRC switches are on the rear
panel — see chapter 3.3 for details.
7 Bridge LED: This illuminates when a channel pair have been switched
into bridged (mono) mode (channel A&B or C&D). Note that the partner
channel's LEDs and controls are disabled when a pair of channels are
bridged. Bridge switches are on the rear panel — see chapter 3.3 for
details of how to connect your speaker to a bridged channel pair.
8 A/P (Auto Protect) LED: If a condition exists, either internally or
externally, that could cause damage to either the amplifier or the
speakers, the protection circuit will disengage the outputs and the
A/P LED will illuminate. The amplifier will continue to be monitored
and depending on the type of fault, will either reset after the fault
has cleared or require manual resetting by switching off at the mains
switch and then on again after a few seconds.
1 2
Power Bridge C-D
PRC C PRC D
-24 -16 -6 -3 Lim -24 -16 -6 -3 Lim
OCM OCM
C -6 D -6
-4 -4 -4
-12 -12
-2 -2
-20 -20
0 0
- dB - dB
Link Link
Typical conditions that could cause the protection to be triggered
include very high frequency or subsonic input signals, DC in the
inputs, short-circuited outputs, or internal high temperatures.
The protection circuit can affect all channels or a 'channel pair'
depending on the type of fault. This is indicated by the combination of
A/P LED and OCM LED illuminating. In this way it is possible for two
channels (a channel pair) to remain functioning even though a fault has
caused the other channel pair to mute. A channel pair would be A&B
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or C&D.
OCM
Temperature related faults will reset if the unit has cooled sufficiently.
Output short circuits will require manual reset after clearing the fault.
-2
Short circuits on either channel of a channel pair will only affect that
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channel pair. A/P will illuminate together with the OCM LED on the
shorted channel and the partner channel of the channel pair (so A&B
or C&D).

3.2 Notes and Switching On

Read all documentation before operating your equipment and retain all
documentation for future reference. Do not spill water or other liquids
into or on the unit and do not operate the unit while standing in liquid.
Do not block fan intake or rear ventilation outlets or operate the unit in
an environment that could impede the free flow of air around the unit.
If the unit is used in an extremely dusty or smoky environment, it should
be cleaned of any collected debris at regular intervals. Please also see
the notes regarding maintenance on chapter 4.1.
It is important that the power output of your amplifier is matched to
the power handling capacity of your loudspeaker. If not, damage to the
loudspeaker could occur.
Switching On
At 'switch-on' the protection circuit will initially activate whilst the
circuits stabilise, indicated by the red A/P LED illuminating, in addition
to various other LEDs. After a few seconds the red A/P LED will
extinguish indicating a satisfactory working condition. Other LEDs
may remain illuminated depending upon rear panel switch settings and
input connections. If the A/P LED does not extinguish after 5 seconds
the unit may be faulty or some external connections may be incorrect
or inappropriate. If this occurs you should power down the unit and
remove all external connections (except for the mains power supply) and
repeat the power up sequence.
CPQ 10 1.0
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