System Requirements The 3M Noise Reduction Module requires a system with a separate outside microphone and speaker. The A121 will not function with an intercom system configured to use a single speaker as both the microphone and speaker. The A121 will work in conjunction with most dynamic microphones and speaker/microphone assemblies. System Configuration The 3M Noise Reduction Module configuration is controlled by two jumper switch (JMP1 and JMP2) settings. JMP1 is used to set the appropriate g

Installing the Noise Reduction board into the 3M Base Station 1. Remove the right-hand and left-hand top covers from the 3M base station. Be careful that the main circuit board does not fall out of the plastic base. 2. See ***Important installation notice*** on next page before performing this step. Plug the A125 ribbon cable onto connector J8, located at the top of the left side of the circuit board. Be careful to support the rear side of the base station circuit board when plugging in the A125