SM1-P-SS-LN Microphone Instructions
The SM1-P-SS-LN is a high quality, ULTRA low noise, high sensitivity, universally powered, flush mount,
omni-directional, pre-amplified microphone with enhanced features for use with DRVs, I/P cameras, etc. Note- the audio
output of the SM1 is jumper selectable “line level” (0db) or “microphone level” (-30db).
SM1 Microphone Placement
Locate the SM1-P-SS-LN Microphone near the area of interest in the room to be monitored. If the entire room is to be
monitored, locate the SM1-P-SS-LN in the middle of the room. Do not mount the microphone near air conditioning vents,
light fixtures or electrical equipment. The SM1-P-SS-LN should be placed as close as possible to the subject(s) to be
monitored. The SM1-P-SS-LN is still 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 SM1-P-SS-LN 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. If you are connecting the SM1-P-SS-LN to an ETS product, connect power to right-most power terminal of the
SM1-P-SS-LN and ground to the ground terminal. The Ground of the power and audio signal must share a common
ground for proper operation.
See Figure 1 for connection diagram.
External Power Source
The SM1-P-SS-LN can be independently powered from any voltage source in the ranges of: 9-42VAC and 12-60VDC. For
DC inputs the SM1-P-SS-LN is not polarity sensitive. You may connect or – of the power source to either of the
two power terminals without damaging the microphone.
See Figure 2 for connection diagram.
Mounting
The SM1-P-SS-LN 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 SM1-P-SS-LN to the surface with screws. A single
gang electrical box can be used for surface mounting or consider using an SM1-P-SS-LNLE in place of the SM1-P-SS-LN.
Adjusting the Lo-Cut and Hi-cut filters
The SM1-P-SS-LN’s high and low frequency response can be trimmed to reduce background noise. If you are primarily
interested in capturing conversations and want to reduce air conditioning and other noises, rotate both controls (hi-cut and
lo-cut) to just short of full clockwise. Some experimentation may be required to achieve the best results for a given
environment.
Adjusting the Automatic Gain Control
The SM1-P-SS-LN features automatic control of gain. This is useful for environments where it is anticipated that sound
levels will range from quiet to loud. This prevents the end user from having to constantly readjust the volume of the base
station to the audio environment and to reduce the possibility of pre-amplifier clipping (distortion). 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 control 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 experiment until
a comfortable medium is found.
Adjusting the SM1-P-SS-LN Volume
The SM1-P-SS-LN output level is set by selecting the desired volume range and adjusting the gain control.
The “Volume Range” jumper should be set to the “LO” position when using the SM1-P-SS-LN with I/P cameras that utilize
“microphone inputs” also know as “Mic. Level” inputs. This sets the maximum gain of the SM1-P-SS-LN’s pre-amp to x14.
The jumper should be placed in the “HI” position when using I/P cameras with “Line level” inputs of DVRs and I/P
cameras. This sets the maximum gain of the SM1-P-SS-LN’s pre-amp to x196.
The SM1-P-SS-LN is shipped with the Volume set at midrange. If the sound at the “head end” is distorted, rotate the
control towards the – mark (counter-clockwise). If the volume at the “head end” is too low, rotate the control towards the +
mark (clockwise). Note- the SM1-P-SS-LN output signal can be used to drive a microphone level input (-60db) of a DVR
or I/P camera by turning the volume all the way down (full CCW) and then CW a small amount.
