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Commercial Audio Series Mixer-Amplifiers
page 13
Operation Manual
3.1 Powering Up
1. Turn off any equipment connected to the Line Out connectors.
2. Plug the amplifier’s power cord into a 3-wire grounded AC outlet.
3. Turn down the input volume controls.
4. Turn down the master volume control.
5. Turn on the Power switch. The Power indicator should glow.
6. Turn the input volume controls in use about 3/4 up.
7. Turn up the master volume control(s) until the desired loudness or power
level is achieved.
8. Touch up the input levels as needed for equal loudness from each micro-
phone.
9. Turn on any equipment connected to the Line Out connectors.
If you ever need to make any wiring or installation changes, disconnect the
power cord.
3.2 Priority Ducking
If you want a microphone to duck (turn down) the background music or other
input signals, follow this procedure. On the back of the 140MPA,
1. Connect a push-to-talk mic contact to the Priority Connector (Figure 3.1).
Input 1 is the priority input for the amplified output, so Input 1 ducks the other
inputs. Threshold of activation depends on input voltage. Ducking does not
affect MOH outputs.
2. Adjust the VOX Threshold trim pot on the back of the unit to set how loud
the voice must be before ducking occurs. It can be set for no ducking.
3. Adjust the Priority Release trim pot for the desired ducking release time.
The Active Indicator lights when ducking is active.
3.3 Music-On-Hold
On the back of the unit, adjust either the 1V or 1W MOH Level Control to obtain
the desired level of Music-On-Hold on your phone system.
Figure 3.1 Priority Ducking Controls
and Connectors
3 Operation