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AMH PROFESSIONAL AUDIO POWER AMPLIFIER INSTALLATION AND OPERATION MANUAL
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 AMH 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 AMH Series amplifier, ensure that:
•
The attenuators are at the “OFF” position (fully anticlockwise).
•
The BRIDGE Switch is not engaged if you are not running the amp in
bridged mode.
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 AMH 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 max position (fully
clockwise, no attenuation). In this position the amplifier operates at full gain.
Turning the attenuator back (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 (12 o’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 AMH Series amplifier when the attenuator is at
maximum position (fully clockwise) is nominally:
+4.0dBu (1.23 volts in) for rated power into a 4 Ohm load.
Each channel of your AMH Series amplifier has a nominal balanced input
impedance of 20kOhms (@1kHz) and should not present a difficult load for
any signal source.
Your signal source (i.e. the equipment feeding signal to the amplifier) should
have an output impedance of 600 Ohms or lower to avoid unwanted high
frequency loss in the cabling.
OPERATION
