Mute All or Unmute All from any Microphone

FAQ #4251 Updated August 31, 2017

Question:

I require eight boundary mics on a table and they must operate as follows: (A) When the switch on any mic is touched, all mics are muted. (B) Once all mics are muted, they are unmuted when the switch on any mic is touched.

Answer:

This can be accomplished by using one Shure SCM810 mixer, eight Shure MX392 mics, one RDL Logic Controlled Momentary Relay ST-LCR1, and one RDL Logic Controlled Latching Relay model ST-LCR2.  RDL = Radio Design Labs.

NOTE 1: This circuit concept will work with any Shure MX microphone that has SWITCH OUT, LED IN, and LOGIC GROUND wires.

NOTE 2: This circuit concept will work with any Shure automatic mixer with TTL logic ports, such as the SCM410 or SCM820.

NOTE 3: All steps below must be completed before the circuit can be tested.

Wiring Configuration:
1)     Powering the ST-LCR1 and the ST-LCR2: Use a single 24 Vdc power supply from Radio Design Labs.  Connect using RDL instructions.

2)     ST-LCR1: Connect a resistor (1,000 ohms, ¼ watt) between the PWR+ terminal (1st from left) and the relay #1 terminal (7th from the left.)

3)     ST-LCR1 to ST-LCR2: Connect a wire from ST-LCR1 relay #1 terminal 9 (9th from the left) to ST-LCR2 terminal 24V+ (5th from left.)

4)     ST-LCR1 to ST-LCR2: Connect a wire from ST-LCR1 GROUND terminal 4 (4th from left) to ST-LCR2 GROUND terminal 4 (4th from left.)

5)     Parallel eight MX392 SWITCH OUT wires, creating a SWITCH OUT bus. Connect this SWITCH OUT bus to the ST-LCR1 SLAVE terminal (3rd from left.)

6)     Parallel eight MX392 LOGIC GROUND wires, creating a LOGIC GROUND bus.  Connect this LOGIC GROUND bus to the ST-LCR1 GROUND terminal 4 (4th from left.)  

7)     Parallel eight SCM810 MUTE IN terminals, creating a single MUTE IN bus. Connect this MUTE IN bus to ST-LCD2 relay #1 terminal 7 (7th from the left)

8)     Connect the SCM810 LOGIC GROUND terminal to ST-LCR2 relay #1 terminal 9 (9th from the left.)  Relay #1 will alternately connect and disconnect the SCM810 MUTE IN bus to the SCM810 LOGIC GROUND.

9)     Parallel eight MX392 LED IN wires, creating a LED IN bus. Connect this LED IN bus to ST-LCR2 relay #2 terminal 10 (10th from the left.) The MX392 LEDs are controlled as a group by ST-LCD2 relay #2.

10)     Connect ST-LCR2 GROUND terminal 4 (4th from left) bus to ST-LCR2 relay #2 terminal 11 (11th from the left.) When any MX392 switch is touched, the ST-LCR2 relay will activate. The MX392 audio will be muted (within the SCM810) by relay #1; the MX392 LED's will be deactivated (when the mics are muted) by relay #2.

11)     Connect the eight MX392 audio signals into the eight Euroblock inputs of the SCM810. Refer to the SCM810 User Guide for proper settings.

12)     Refer to the MX392 User Guide for instructions on how to set the internal DIP switches.  Each MX392 setting is DIP #1, #2, and # 4 = OFF; DIP #3 = ON.  Each MX392 MUST be set to Momentary switch operation.

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