SM1-W Microphone Instructions
The SM1-W is a high quality, 12VDC powered, flush mount, omni-directional, pre-amplified, weather resistant microphone
for use with DRVs, I/P cameras, etc. Note- the audio output of the SM1-W is “line level” (0db). Note- the audio output of
the SM1 is jumper selectable “line level” (0db) or “microphone level” (-30db).
SM1-W Microphone Placement.
The SM1-W is designed for outdoor applications. It is important to locate it in an area that is not subject to driving rains or
excessive water flow because water will enter the space behind the sound chamber and damage the electronics. Do not
mount the microphone near air conditioning vents, light fixtures or electrical equipment. The SM1-W should be placed at
least five feet away from the subject(s) to be monitored. The SM1-W is still useable in the range of 15-25 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-W 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.
Sound Chamber Wind Screen
Over time the wind screen may become saturated with moisture or dirt and the sound quality and volume will be
noticeably reduced. If this happens, remove and soak the screen in soapy warm water. Then, rinse and wring out the
excess water from the screen and reinstall it.
Mounting
The SM1-W is designed to be surface mounted on any flat surface or on an exterior single gang “bell” electrical box. Be
sure to use the supplied gasket to prevent water from entering the electronics.
Adjusting the SM1-W Gain
The SM1-W 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-W with I/P cameras that utilize
“microphone inputs” also know as “Mic. Level” inputs. This sets the maximum gain of the SM1-W’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-W’s pre-amp to x196.
The SM1-W is shipped with the gain 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).
Setting the SM1-W Hi-Cut/Lo-Cut Jumpers
The normal frequency response of the SM1-W microphone is 500-13Khz. When both jumpered “in”, The “HI Cut” and “Lo
Cut” filters set the SM1-W’s frequency response to 900-6Khz . Enabling one or both of the filters is useful when
background noise needs to be further reduced and intelligibility of speech emphasized. We recommend experimenting
with the jumper settings to achieve the best acoustic result for your application.
