User Manual

PAGE 8
OPERATION
IMPORTANT
All signal source equipment should be adequately earthed.
This not only ensures your safety, but everybody else’s as well.
Faults can and do occur in mains connected equipment where
the chassis can become "live" if it is not properly earthed. In
these instances, the fault in a "floating" (ungrounded) piece of
equipment will look for the shortest path to ground, which
could possibly be your amplifier’s input. If the fault current is
large enough, it will destroy the input to your amplifier and look
for the next available path, which may be you!
Before making any connections to your IS Series amplifier, observe the
following:
Ensure the mains voltage supply matches the label on the rear
panel of your amplifier (+/- 10%).
Ensure that the power switch is OFF.
Ensure that all system grounds (earth) are connected from a
common point. Avoid powering equipment within a system from
multiple power sources that may be separated by large distances.
Check the continuity of all interconnecting leads to your amplifier;
ensure that there are no open or short circuited conductors.
Ensure that the power handling of your load (speakers) can
adequately cope with the power output of the amplifier.
Before operating your IS Series amplifier, ensure that:
The attenuators are at the "OFF" position (fully anticlockwise).
The GROUND LIFT Switch is not engaged (should be in the
"Ground" position).
POWERING UP
REMEMBER
The amplifier should be the last piece of equipment that you turn on
and the first piece of equipment that you turn off.
We recommend turning the attenuators on your amplifier down when
turning the unit on. When you power up your IS Series, your amplifier
goes through an initialising period before it will accept signal. The
Inrush Current Suppression (ICS) circuit is in operation for the first 0.5
seconds. This limits the mains current, to prevent "nuisance-tripping" of
circuit breakers. During this period you will hear a couple of relays
"click", indicating mains is now directly applied to the amplifier and the
signal path is connected. While the ICS circuit operates there is also a
30dB mute on the signal input. After two seconds this mute will
release, allowing any applied signal to pass un-attenuated. When
switching the amplifier off, wait a couple of seconds before switching
the amplifier on again. This allows the ICS circuit to reset.
LEVEL MATCHING
The normal operating position for the attenuator is the maximum
position (fully clockwise, no attenuation). In this position the amplifier
operates at full gain. Turning the attenuator down (anticlockwise)
reduces the input sensitivity.
NOTE: If full power output is required, you should
operate your amplifier with the front panel attenuator
above the half way (12o clock) position, otherwise
clipping of the input circuitry (and its resultant
distortion) will occur before full output power is
achieved.
SENSITIVITY
Your amplifier is a linear device operating with a fixed input to output
voltage gain (less attenuation). The maximum output voltage swing is
determined by the applied mains voltage, load, load type and the duty
cycle of the applied signal. The input sensitivity for your IS Series
amplifier when the attenuator is at maximum position (fully clockwise)
is determined by the Input Sensitivity switch.
There are 3 settings for rated power into a 4 ohm load.
0.775V in for rated power out
1.0V in for rated power out
1.44 V in for rated power out.
Each channel of your IS Series amplifier has a nominal balanced input
impedance of 20kOhms (@1kHz) and should not present a difficult load
for any signal source. (i.e. the equipment feeding signal).
IS SERIES INSTALLATION & OPERATION MANUAL