ETS SM3 Instructions

SM3 Monitoring Station Instructions
The SM3 is a single channel, one way "listen only" base station for use with any ETS SM1 series microphone. The SM3
can be used independently or with a CCTV system. The SM3 also easily connects to recording equipment such as DVRs,
linear time-lapse VCRs and audio tape recorders. Note the audio input / output signals of the SM3 are "line level" (0dbm).

SM1 Microphone Placement.

Locate the SM1 microphone near the area of interest in the room to be monitored. If the entire room is to be monitored,
locate the SM1 in the middle of the room. Do not mount the microphone near air conditioning vents, light fixtures or
is
electrical equipment. The SM1 should be placed at least 5 feet away from the subject(s) to be monitored. The SM1 still
s
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.

SM1 Mounting

To flush mount the SM1 on ceilings or walls, cut a 2 ¼" by 2 " hole in the wall or ceiling tile to allow room for the circuit
¾
board and mount the SM1 to the surface with screws. For surface mounting, purchase the ETS SM1-LE omni-directional
microphone or use a single gang electrical box.

Cable Run

Run a 22 gauge, stranded, two conductor shielded cable between the SM3 amplifier and the SM1 microphone. Keep the
cable run distance under 1,000 feet and away from AC power sources, light fixtures and electrical equipment. See Figure
1 for connection diagram.

SM3 Recorder switch

If the SM3 kit will be used with a recorder of some type, place the recorder switch in the "IN" position. In this position, both
live audio and playback audio can be heard through the SM3s internal speaker. In stand alone applications where there is
no recorder or no need to playback recordings, place the recorder switch in the "OUT" position.

SM3 Headphone jack

Plug in a set of 3.5mm stereo headphones for private listening. The internal speaker of the SM3 will be automatically
disabled until the headphones are unplugged.

Adjusting the SM1 Gain

Start with a midrange setting of the gain control on the SM1. Adjust the control + or – for maximum clarity. If the sound at
the amplifier is distorted, rotate the control towards the – mark (counter- clockwise). If the volume at the amplifier is too
low, rotate the control towards the + mark (clockwise).

Setting the SM1 Jumpers

The SM1 microphone has jumper selectable treble boost and limiter circuits. The treble boost circuit when jumpered in,
emphasizes the high frequency sounds that the microphone picks up. This is useful for improving the sound quality on
slow speed tape recordings (VCR time-lapse recordings). The limiter circuit, when jumpered in, automatically keeps the
SM1's output at a relatively constant level. This eliminates the need for the listener to reduce the volume control on the
amplifier when sounds get louder.
Note: Do not use the SM1's limiter circuit if you are using a tape recorder or other device that uses an AGC or limiter
circuit. Most tape recorders have limiter circuits. The recommended jumper settings are as follows:
Stand-alone Application Tape Recorder Application
Limiter "IN" "OUT"
Treble Boost "OUT" "IN"