Shure SCM810 Manual page 10

SCM810 Eight-Channel Microphone Mixer
In the following paragraphs, the wiring diagrams refer to the DB-25 connector
pins shown in Figure 4.
Cough Button
The talker can turn off his or her microphone during coughing 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 12-
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 section for
more information on MUTE IN logic).
M1 M3
M2
COUGH BUTTONS FIGURE 12
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 13-the chairperson is shown as Channel 1). An al-
ternative to a switch is to connect the chairperson's GATE OUT to the MUTE
IN of other channels. When the chairperson's microphone activates, all other
microphones mute.
CH. 1
M2 M4
CHAIRPERSON-CONTROLLED MUTING FIGURE 13
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 14 (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, separate shielded pairs must be used. Failure to carry
the dc power on a shielded pair may result in audible clicking due to capacitive
coupling between the dc power lines and microphone lines.
10/13
LOGIC
GROUND
LOGIC
GROUND
M3 M5 M5 M7
M6
+
G1
G2
REMOTE CHANNEL-ON INDICATORS FIGURE 14
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 Logic Ground pin. The selected
channels now function as they would in a non-automatic mixer (see Figure
15-Channels 1, 2 and 3 modified).
O2
O1 O3
GATING BYPASS FIGURE 15
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 pre-
vents its audio from appearing 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 in-
clude:
• 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 activating micro-
phones by taking the following steps.
1. Place one microphone near the unwanted sound source. Connect that
microphone's signal to a channel input,
-or-
connect the unwanted sound source directly into a Mic/Line channel input.
2. Mute that channel using the logic terminal (see Figure 16-Channel 1 is
muted).
3. Adjust that channel's gain control just to the level where other micro-
phones 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 con-
tinue to activate other microphones.
Shure Incorporated
–
5 V POWER
SUPPLY
LOGIC
GROUND
G3
R = 470 , 1/4 W
LOGIC
GROUND
2017/10/09