Instruction Manual

SMDA4 Distribution Amplifier
Instructions
The SMDA4 is a 4 channel active “signal splitter”. It is designed to power up any SM1 series
microphone and distributes the audio signal to up to 4 DVRs, I/P cameras, etc.
SM1 Microphone Placement
Locate the SM1 microphone as close as possible to the area of interest in the space to be
monitored. Do not mount the microphone near air conditioning vents, light fixtures or electrical
equipment. The SM1s should be placed at least 5 feet away from the subject(s) to be monitored.
An SM1 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.
SMDA4 location and power
The SMDA4 interface box is designed to be located next to a DVR or I/P camera. The SMDA4
requires a 120VAC power source within 3 feet of its location. If this is not possible in your
application, you can splice in up to 100 feet of 18 awg, 2 conductor cable to extend the distance
between the AC power source and the SMDA4.
Cable Run
Run a 22 gauge, stranded, two conductor shielded cable between the SMDA4 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.
SMDA4 Inputs
The input to the SMDA4 can be connected directly to any Sound Surveillance microphone or any
other “line level” input signal (“AUX” input). Use one input type only. Do not use both inputs at the
same time.
SDA4 level controls
The overall input level is controlled with the Master level control. This control provides x2 gain for
weaker input signals or attenuation for stronger signals. The Master level controls the volume of
audio that is fed into each channel output. Each audio output level can also be individually
adjusted. This is useful if some “head end” equipment is more or less sensitive to larger or
smaller signal levels. Experimentation will determine what positions are appropriate.
SMDA4 audio outputs
These outputs are typically connected to the audio inputs of DVRs, I/P cameras, etc. You can
extend these outputs up to 1000 feet using audio coaxial cable and field installable RCA (or
3.5mm) connectors. These outputs can be connected to any ETS base station microphone input.
Cut one end off the supplied patch cable. Strip the cable back and connect the center conductor
of the coax to the “audio” terminal and the shield to the “-“ terminal of any microphone input. No
connection is needed on the “+” terminal.