Clear-Com AB-120 - Manual (Page 9)

Clear-Com Communication Systems
AB-120 Announcer Console Instruction Manual
1 - 3
FRONT PANEL
Figure 1-2: AB-120 Front Panel Controls
Selecting Microphone Amplifier Gain
The microphone preamplifier and the output line drive amplifier have
selectable gains allowing the user to tailor the gain structure to the type
of microphone being used and the desired output level. As shipped
from the factory, microphone gain is set for a dynamic mic and the
output level is set for -10 dBu.
Microphone Preamplifier Gain
The microphone preamplifier gain must be set to provide proper
operation of the limiter circuit used in the talkback system. The
preamplifier can be set for gains of 40, 50, and 60 dB. Dynamic
microphones have a nominal output level of approximately -60 dBu.
Electret mic typically have an output level of -40 dBu. Jumpers JP9
and JP10 allow selecting the preamplifier gain to 40, 50, and 60 dB.
Jumpers JP9 and JP10 are normally factory set for -60 dB (dynamic
microphone).
INPUT LEVEL JP 9 JP 10
-60 dB (dynamic microphone) 1-2 1-2
-50 dB 2-3 1-2
-40 dB (Electret microphone) 2-3 2-3
Interrupt Interrupt Non-Interrupt Non-Interrupt
AB-120
Announcer Console
Interrupt
Level
Control
Non-Interrupt
Level
Control
Mute
Indicator
Mute
Button
Talk Back
Indicator
Talk Back
Button