Operation
9
ALC
(Rear Panel; #17)
The TEL input features an automatic level control (ALC) which compen-
sates for different voice levels and speaking styles of the individuals using
the system. The amplifier is shipped with this control in the OFF (max.
counterclockwise) position.
To adjust the ALC:
1. Rotate the MIC 5/TEL and MASTER controls to the highest level likely
to be used.
2. Speak softly and distinctly into the telephone mouthpiece while
adjusting the MIC 5/TEL volume control to the desired output level.
3. Speak in a loud voice directly into the telephone mouthpiece while
rotating the ALC control clockwise to the point where the output of the
amplifier is reduced to the same level as that obtained in Step 2.
4. The MIC 5/TEL and MASTER controls can be used to vary the overall
volume without upsetting the ALC adjustm
ent.
VOX
(Rear Panel; #18)
The telephone page input features voice-activated AUX muting. This feature
always mutes AUX 2 and only mutes AUX 1 when the AUX1/MIC 6 switch
is set in that position.
The VOX control should be set so that only the desired signal is above
the threshold level, while unwanted noise is below it.
To adjust the sensitivity of the VOX circuit:
1. Rotate the VOX control fully clockwise. While making a public address
announcement and talking at a low level, the sound should not be
choppy or missing parts of words. If it is choppy or intelligibility is poor,
rotate control counterclockwise to the point where the sound is clear
and crisp (but not to the maximum counterclockwise position).
2. If the background music shuts down when no page is in progress,
rotate the control clockwise until the music will not shut down when
no page is in progress.
Variable Mute
(Rear Panel; #4)
The VAR MUTE control mutes the AUX input(s) only during telephone
pages. The control allows the user to select from 4 levels of muting:
1 = -60 dB, 2 = -21 dB, 3 = -10 dB, 4 = 0 dB.
