Inter-M MA-106A - Manual (Page 9)

PUBLIC ADDRESS AMPLIFIER
6 MA-106A
6a) MANUAL MUTE CONTACT CLOSURE
Contact Closure between pins 1 and G will mute input channel 2, or mute channels 2 and 3 together if they
are linked using mix configuration switch #6. This is typically used when a microphone plugged into channel
1 has a push-to-talk switch, whereby the pressing of the switch not only turns on the mic but also mutes the
signal on channel 2, or channels 2 and 3 if they are linked. When the switch is released, the signal on
channels 2 and 3 returns.
6b) MASTER SYSTEM STANDBY
The MA-106A has a power saving standby mode which can be triggered by 25 minutes of audio
inactivity (below a certain audio input level), or by contact closure of the Master System Standby connector
pins G & 2. When in standby mode, the front panel power LED will turn red, changing back to blue for
normal operating mode. Standby mode is ended when there is audio signal present again, or when the
Master System Standby circuit is opened. Master system standby has priority over standby due to inactivity.
7. ZONE 2 LEVEL CONTROL
This controls the level of the Zone 2 output signal.
8. MIX CONFIGURATION DIP SWITCHES
- Switches 1, 2, and 3: Zone 2 Assign
These assign each input to Zone 2 output, post-level control. There is no effect to the main output mix.
- Switches 4-5: VOX Trigger -
The MA-106A has the ability to trigger a mute on channel 2 or 3 from the presence of an audio signal on
channel 1 or 2. This is called Voice Operated Switching, or VOX. Input 2 has priority over input 3, and
input 1 has priority over input 2. Input 1 also has the ability to use a contact closure trigger such as a mic
push-to-talk switch for priority muting of channel 2. Additionally, input 1 can be set to have priority over
both inputs 2 and 3 together (see switch 6).
The MA-106A has audio detecting LEDs on each input. When the VOX TRIG switches are set to ON for
inputs 1 or 2, the same signal level which activates the LED is used as the VOX trigger. VOX mutes the
dependent channel until the trigger signal falls back below the LED threshold. Each input features a rear
panel gain trim that first optimizes the overall input sensitivity for each input, but can also serve to fine-tune
the sensitivity of the signal detector which creates the VOX trigger point for each input.
- Switch 6: Mute Link 2&3
When this switch is turned on, it sets the channel 1 VOX trigger or Manual Mute contact closure to mute
both channels 2 and 3. If only channel 2 is to be affected, leave it off.
- Switch 7: Low-Cut Filter
This switch turns on a 400Hz 6dB/oct low-cut filter affecting the main and PRE outputs but not the zone 2
outputs. This is useful for providing the proper EQ for paging horns.
- Switch 8: CH 1 MIC Phantom Power
This provides +18V phantom power to input 1 for use with condenser and electret microphones.
9. INPUT 3 GAIN CONTROL
Input 3 gain trim range is adjustable from -10dB to +10dB.
10. INPUT 2 GAIN CONTROL
Input 2 gain trim range is adjustable from -10dB to +10dB. This control is also used to fine tune the signal
threshold that will trigger the muting of input 3.
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