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Commercial Audio Series Mixer-Amplifi ers
Operation Manualpage 12
3 Operation
Figure 3.1 Priority Muting Controls and Connectors
3.1 Powering Up
1. Turn off any equipment connected to the Preamp Output connector.
2. Plug the amplifi er’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 music and voice.
9. Turn on any equipment connected to the Preamp Output connector.
If you ever need to make any wiring or installation changes, disconnect the power cord.
3.2 Priority Muting
If you want a microphone’s push-to-talk switch to mute the background music or other input
signals, follow this procedure. On the back of the 135MA or 160MA,
1. Turn DIP switch 2 off. Turn DIP switch 3 on.
2 . Connect a push-to-talk mic contact to the Priority Connector (Figure 3.1). Input 1 is the
priority input for the amplifi ed output, so Input 1 mutes the other inputs.
3.3 Voice-Activated (VOX) Muting
If you want a voice to mute the background music or other input signals, follow this proce-
dure. On the back of the 135MA or 160MA,
1. Turn DIP switch 4 on. Turn DIP switches 2 and 3 off.
2. Talk into the microphone. Adjust the VOX Threshold trim pot on the back of the unit to set
how loud the voice must be before muting occurs. It can be set for no muting.
3.4 Music-On-Hold
On the back of the unit, adjust MOH Level Control to obtain the desired level of Music-On-
Hold in your phone system.
3.5 Security Knobs
To prevent user tampering with the knobs, you can order the accessory 10-pack of security
knobs from your Crown dealer, part no. S-Cover.
1. Pull off an existing knob.
2. Remove the nut.
3. Screw the security knob over the potentiometer shaft. The knob will not rotate.
Input 1
PRIORITY
Mic push-to-talk switch