SM1-PE Microphone Instructions
The SM1-PE is a high quality, flush mount, omni-directional, pre-amplified microphone with enhanced
features for use with DRVs, IP cameras, etc. Note- the audio output of the SM1-PE is switch selectable
“line level” (0db) or “microphone level” (-30db).
SM1 Microphone Placement
Do not mount the microphone near air conditioning vents, light fixtures or electrical equipment. The SM1-
PE should be placed as close as possible to the subject(s) to be monitored. The SM1-PE 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 SM1-PE 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 SM1 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 to the surface with
screws. A single gang electrical box can be used for surface mounting or consider using an SM1-PE-LE
or SM1-PE-LE2 in place of the SM1-PE.
Adjusting the Lo-Cut and Hi-cut filters
The SM1-PE’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. Experimentation with the settings may
be required to achieve the best results for a given environment.
Adjusting the Automatic Gain Control
The SM1-PE 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 SM1-PE Volume
The SM1-PE output level is set by selecting the desired volume range and adjusting the gain control.
The “Volume Range” switch should be set to the “LO” position when using the SM1-PE with IP cameras
that utilize “microphone inputs” also known as “Mic. Level” inputs. The switch should be placed in the “HI”
position when using IP cameras with “Line level” inputs of DVRs and IP cameras. The SM1-PE is shipped
with the Volume set at midrange. If the sound at the “head end” is too loud and / or distorted, rotate the
control - CCW. If the volume at the “head end” is too low, rotate the cCW.
