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19
English --
The AMS8100 can prevent these and similar sounds from
activating microphones by taking the following steps.
1. Place one microphone near the unwanted sound source.
Connect that microphone’s signal to a channel input,
2. Mute that channel using the logic terminal (see illustration
INHIBITING GATING FOR UNWANTED SOUNDS
—
Channel 1 is muted).
3. Adjust that channel’s gain control just to the level where
other microphones in the system do not activate for the
unwanted sound. If the channel gain is set too high, other
system microphones will be difficult to activate for
desired
sounds. If set too low, unwanted sounds will continue to
activate other microphones.
INHIBITING GATING FOR UNWANTED SOUNDS
M1
LOGIC
GROUND
Loudspeaker Muting
Some applications require a loudspeaker to be placed
near each talker to provide audio reinforcement, or to permit
telephone conversation or conference monitoring. Each loud-
speaker can cause feedback unless it is automatically
switched off when the talker near it speaks. To provide this
function, connect the GATE OUT terminal of each channel to a
separate loudspeaker muting relay as shown in illustration
LOUDSPEAKER MUTING
(Channels 1, 3 and 5 shown modi-
fied). Recommended relays are Radio Shack 275--248, Om-
ron G2R-14-DC12 (Digi-Key number Z745-ND), Potter &
Brumfield R10-E1Y2-V185 (Newark number 45F106), or
equivalent.
NOTE:
A diode across each relay coil is required to
suppress inductive voltage spikes which may damage the
AMS8100.
An existing sound system using 24-volt relays can be
used with the AMS8100 without modification if the relay coil
current draw is under 500 mA.
LOUDSPEAKER MUTING
+
--
12 V
POWER
SUPPLY
G5
G3
G1
LOGIC
GROUND
D = 1N4148
FROM
POWER
AMP
D
D
D
“Filibuster” Mode
In normal operation, when several people talk, each mi-
crophone gates on so that no speech is missed. In “filibuster”
action, a microphone that is gated on prevents other micro-
phones from gating on. Once a microphone has gated on, oth-
er microphones cannot gate on until the talker has paused long
enough for that microphone to gate off. Thus the person talking
has the floor and cannot be interrupted.
To establish this function, first perform the internal Mute to
“Inhibit” modification (see
Internal Modifications
). Then con-
nect all the MUTE IN pins of the modified channels together, all
the GATE OUT pins of the modified channels together, and the
GATE OUT pin of one modified channel to the MUTE IN pin of
another modified channel (see illustration
“FILIBUSTER”
MODE
—Channels 1, 2 and 3 modified). Turn the Last Mic
Lock-On switch (SW902, position 2) to off.
NOTE:
To prevent high-frequency oscillation, do not wire
a channel’s GATE OUT pin to its own MUTE IN pin unless the
Mute to “Inhibit” change has been made.
“FILIBUSTER” MODE
JUMPER
G1
M1
G3
M3
M2
G2
LOGIC
GROUND
Inhibit Function
See
Internal Modifications
.
Diode Isolation of Logic Controls
Two or more control functions using the same logic pins
can be isolated with diodes. In this manner a channel can be
muted by an overall group mute switch, or by its own cough
button (see illustration
DIODE ISOLATION OF LOGIC CON-
TROLS
—Channels 1, 3 and 5 modified).
DIODE ISOLATION OF LOGIC CONTROLS
GROUP
MUTE
COUGH
BUTTONS
D = 1N4148 OR
EQUIVALENT
M1
M3
M5
LOGIC
GROUND
D
D
D