Installation Instructions

SM1-TRW Microphone Instructions
The SM1-TRW is a stainless steel, tamper resistant, weather resistant, high quality, 12VDC
powered, flush mount, omni-directional, pre-amplified microphone with a for use with DRVs, I/P
cameras, etc. Note- the audio output of the SM1-TRW is “line level” (0db).
SM1-TRW Microphone Placement.
Locate the SM1-TRW Microphone near the area of interest be monitored. Do not mount the
microphone near air conditioning vents, light fixtures or electrical equipment. The SM1-TRW
operates optimally at 3 to 5 feet away from the subject(s) to be monitored. The SM1-TRW 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-TRW 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-TRW can be surface or flush mounted on 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-TRW to the
surface with screws (sound hole side down). A single gang outdoor rated electrical “Bell box” can
be used for surface mounting. BE SURE TO USE SUPPLIED GASKET to prevent water from
leaking into the back side of the microphone
Adjusting the SM1-TRW Gain
The SM1-TRW 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-TRW Jumpers
The SM1-TRW microphone has jumper selectable treble boost and peak limiter circuits.
The limiter circuit lowers the gain of the microphone preamplifier, preventing it from clipping
during very loud sound intervals. During normal audio levels, the limiter circuit has no affect on
the audio signal and there won’t be any observable result in performance. If there will be periods
of high volume in your application, jumper the limiter “in”. Note-as the gain control is decreased,
the limiter will have less affect on the pre-amplifier during loud sound intervals.
The Treble boost circuit emphasizes the high frequencies of the pre-amplifier. Jumpering treble
boost to the “in” position will result in improved pick up of faint conversations such as whispers.
Note however, when the treble boost is on, background and amplifier noise will increase as well.