DM1-SS Microphone Instructions
The DM1-SS is a flush mount omni-direction microphone with an integrated DSP (Digital Signal
Processor) based background noise eliminator unit. It is designed to Digitally screen out all repetitive
background sounds and passes through / enhances the human voice.
Note
- the audio output of the DM1-SS is “line level” (0db).
DM1 Microphone Placement
Do not mount the microphone near air conditioning vents, light fixtures or electrical equipment. The DM1 should
be placed as close as possible to the subject(s) to be monitored. The DM1 is useable at distances of up to 25
feet but is dependent on the level of background noise in the area. Experimentation in the environment will
determine what distances work best.
Cable Run
Run a 22 gauge, stranded, two conductor shielded cable between the DM1 microphone and the monitoring
device. Keep the cable run distance under 1,000 feet and away from AC power sources, light fixtures and
electrical equipment. Connect power to the + terminal, the audio signal to the “audio” terminal and ground to the –
terminal. The Ground of the power and audio signal must share a common ground for proper operation.
See
Figure 1 for connection diagram.
Mounting
The DM1-SS can be surface or flush mounted on ceilings or walls. For flush mounting, cut a 2 ¼” by 2 ¾
“ hole in
the wall or ceiling tile to allow room for the circuit board and mount the DM1-SS to the surface with screws. A
single gang electrical box can be used for surface mounting or consider using an DM1-SS in place of the DM1-
SS.
Adjusting the Automatic Gain Control (COMPP)
The DM1 features automatic control of gain. This is useful for environments where it is anticipated that sound
levels will range from quiet to loud. The best way to set this control is to adjust it to a comfortable volume level (on
an ETS base station or PC monitor speakers) when the loudest sounds are present and constant. Turning the
c CW will increase the amount of gain reduction during loud sound intervals. If the sound is reduced too
much during loud sounds, turn the control - CCW a small amount and continue experimenting until a comfortable
medium is found.
Adjusting the DM1-SS Level
Start with the Level set at midrange. If the sound at the “head end” is distorted, rotate the control towards the –
mark (counter-clockwise CCW). If the volume at the “head end” is too low, rotate the control towards the + mark
(clockwise CW). Note- the DM1-SS output signal can be used to drive a microphone level input (-60db) of a DVR
or IP camera by turning the volume all the way down (full CCW) and then CW a small amount.