Interface Elements - Field Acoustics UK 500 Instruction Manual

3. Interface Elements, Front Panel.
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(1) Power Switch
This switch controls the power supply to the amplifier. There is a short delay on power-up,
this is to avoid switch-on "thump" which could damage the loudspeakers.
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(2) Gain Controls
The level of each Channel is individually adjusted by these controls.
Rotating these controls fully clockwise, results in no attenuation to the incoming audio signals.
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(3) Indicator Section, Status:
a. Power Indicator
This indicator shows when the amplifier is on and is receiving power.
b. Parallel Mono Mode Indicator
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This indicator shows if (parallel) MONO mode is selected on the rear panel.
For channel pair A and B only Input A will be used to drive both channels. Full
independent level control of the amplifier output stages is still possible via the Gain
controls.
Bridged Mono Mode Indicator
c.
This indicator shows if Bridged mode is selected on the rear panel. It is most
important that this indicator is not illuminated unless bridged mode is required.
This is because when bridged mode is selected, Channel A will be out of phase
with Channel B. This will result in poor bass response and an unsatisfactory sound
if left and right outputs are used. In this mode Channel A controls the output level.
d. Protect Indicators
These indicators light briefly during the power up cycle and also light should a
fault occur. Illumination of the protect indicators, shows that the output of the
amplifier has been disconnected by means of an internal relay to protect connected
speaker systems from being damaged by the fault.
(4) Indicator Section, Signal levels:
a. Output Level Display
These show the (Peak) output level of the amplifier for each channel, in both
Stereo and Mono modes. It is useful to note for trouble shooting, that the sensors
for the Output Level Display, detects levels after the output relays. Therefore if the
display is operating, a signal is present at the speaker sockets.
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