Shure SCM810 User Manual page 11

SUGGESTED LOGIC APPLICATIONS
This section contains suggestions on the uses of the
SCM810's logic capabilities. Note that uses of these functions
are not limited to the listed applications. The user is limited only
by individual imagination and creativity. For additional sugges-
tions and solutions to installation problems, contact Shure's
Applications Group.
In the following paragraphs, the wiring diagrams refer to the
DB-25 connector pins shown in Figure 10.
Cough Button
The talker can turn off his or her microphone during cough-
ing or private conversations by installing an SPST pushbutton
switch between the MUTE IN and Logic Ground pins for each
channel to be modified (see Figure 11 -– Channels 1, 2 and 3
modified). When a channel is muted, no audio is passed. (See
"Dead Zone on MUTE IN Defeat" in Internal Modifications sec-
tion for more information on MUTE IN logic.)
M1
M2
COUGH BUTTONS
FIGURE 11
Chairperson-Controlled Muting
The chairperson can, by activating a switch, silence all other
microphones and be heard without interruption. For operation
in this mode, connect all the MUTE IN pins together except that
of the chairperson' s channel , and wire an SPST pushbutton or
toggle switch between those MUTE IN and Logic Ground pins
(see Figure 12—the chairperson is shown as Channel 1).
An alternative to a switch is to connect the chairperson's
GATE OUT to the MUTE IN of other channels. When the chair-
person's microphone activates, all other microphones mute.
Remote Channel-On Indicators
Remote indicators can be used to indicate when a talker's
microphone is on. Connect the LEDs and a 5-volt supply to the
GATE OUT pins as shown in Figure 13 (Channels 1, 2 and 3
shown modified). To avoid switching clicks in the audio output,
do not ground the power supply negative terminal in the audio
system or rack ground. IMPORTANT: If a single cable is used
for the microphone audio signal and the LED dc power, sepa-
rate shielded pairs must be used. Failure to carry the dc power
on a shielded pair may result in audible clicking due to capaci-
LOGIC
GROUND
M3
tive coupling between the dc power lines and microphone
lines.
Disabling the Gating Function (Bypass)
To keep certain microphones on at all times, wire the desired
microphone channel's OVERRIDE IN pins together to the Log-
ic Ground pin. The selected channels now function as they
would in a non-automatic mixer (see Figure 14—Channels 1, 2
and 3 modified).
O1 O3
GATING BYPASS
Inhibiting Gating for Unwanted Sounds
As described in the Operating Principles section, MaxBus
attempts to activate only one microphone per sound source.
Muting a microphone channel prevents its audio from appear-
ing at the mixer's output. However, the muted microphone still
communicates with other mic channels via MaxBus. A sound
source picked up by a muted microphone will not activate other
microphones.
Sound sources that may cause unwanted microphone
channel activation include:
A noisy fax machine or printer
A squeaky door
A paging system loudspeaker
An audio teleconferencing return signal loudspeaker
The SCM810 can prevent these and similar sounds from ac-
tivating microphones by taking the following steps.
1. Place one microphone near the unwanted sound source.
Connect that microphone's signal to a channel input,
connect the unwanted sound source directly into a Mic/Line
channel input.
2. Mute that channel using the logic terminal (see Figure 15 ––
Channel 1 is muted).
11
GROUND
O2
FIGURE 14
-– or -–
LOGIC