Front Panel
The
KA
KA
KA
KA
KA
Series models have identical front panel
layouts.
Figure 1
shows the panel layout of the
KA
KA
KA
KA
KA
Series. The
functions of the controls and indicators are as follows:
1 Attenuator
Level control for your amplifier is provided by a 21
position detented potentiometer and indicates
gain reduction in decibels from the 0 dB position
(maximum gain, no attenuation).
2 Status Indicator
This is a dual color LED which displays the status
of the output stage and displays three levels of
operation.
These levels are:
Below 1 watt
(unlit)
1 watt and above
(green)
1dB below actual clipping
(red)
The LED will turn green once the output voltage
exceeds 2.828 volts (1 watt re 8 ohms or 2 watts
re 4 ohms). This is equivalent to:
24.5dB below rated power for a KA800 or
26.0dB below rated power for a KA1200.
The LED will change to red once the output
exceeds the -1dB point before actual clipping of
the amplifier’s output stage. The threshold of the
-1dB point is referred to the amplifier supply rails
and alters with changes in the mains supply,
changes in the load and duty cycle fluctuations.
The attack and decay time (ballistics), of the
status circuit are those of a Peak Programme
Meter (P.P.M.)
If using this indicator to line up sensitivities, apply
a steady state tone (e.g. slate on a mixing console).
The 1 watt level is the mid-point between the
indicator illuminating and extinguishing green.
NOTE: The amplifier is not damaged by running
into clipping, but speakers may be. To maximise
the life of your speakers, try to keep clipping
infrequent.
3 Fault Indicator
This amber LED will flash when a fault condition
exists.
The fault detection circuit monitors the difference
between drive and output in your amplifier.
If you have a short on the speaker output (or a
blown negative rail fuse) the LED will flash brightly
in sync with the programme. This LED will also
flash with programme peaks for gross overloads
or if the load is 2 ohms or less.
The circuit has two stages of operation:
1. It will provide indication (e.g. gross overload)
but does not affect the input signal (a faint flash).
2. It will indicate and mute the input signal (e.g
shorted output) (brightly flashing or permanently
on).
4 Power Switch
Press the switch to the
right
for power
on
(
I
)and
to the
left
for power
off
(
0
). At start-up (turn-on)
the input to the amplifier is muted by 30dB for
approximately two seconds.
5 On/Thermal Indicator
This is a dual colored LED which will normally be
green
and indicates that the amplifier is on and
receiving mains power.
In the advent of a thermal overload this LED will
turn
red
indicating that the internal operating
temperature of one or both amplifier channels has
exceeded a safe level of operation and the
channels will be automatically muted. The fans
will continue to run and once the effected channel/
s have had a cool-down period, they will un-mute
and return to normal operation.
NOTE: You should always ensure that the fan
grille is kept clean and free from the build up of
dust and lint. This will ensure longer operation of
your amplifier and reduce the possibility of it
prematurely going into thermal shutdown mode.
Controls & Connectors 7