STWI5-2 Dual Microphone Speaker Kit Instructions
The STWI5 is a two zone two-way audio surveillance system (intercom accessory) designed to be used with DVRs, I/P
cameras etc. Note- the audio signals going into and out of the STW1 are “line level” (0dbm). STW1s are not
recommended for outdoor use where they may be exposed to water.
STW1 Microphone / Speaker Placement.
Locate the STW1 as close as possible to the area of interest in the space to be monitored. If a large area is to be
monitored, locate the STW1 in the middle of the space if possible. Do not mount the STW1 near air conditioning vents,
light fixtures or electrical equipment. The STW1 should be placed at least 5 feet away from the subject(s) to be monitored.
The STW1 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.
STWI-2 Interface box location
The STW1 interface box is designed to be located next to a DVR or I/P camera. The STW1 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 20 awg, 2
conductor cable to extend the distance between the AC power source and the STW1.
Cable Runs
Run 2 each 22 gauge, stranded, two conductor shielded cable between each STW1 microphone / speaker and the STWI-
2 interface. Keep both cable run distances under 250 feet and away from AC power sources, light fixtures and electrical
equipment.
See Figure 1 for connection diagram.
Mounting
To flush mount the STW1 on ceilings or walls, cut a 3.5” x 2.25” rectangular hole in the wall or ceiling tile to allow room for
the circuit board and mount the STW1 to the surface with screws. The STW1 can also be mounted on a double gang
electrical box.
STW1 Optional Call Switch
Connect this switch (STW1 terminals cs1 and cs2) to equipment that permits a “page” signal input. It is a N.O. (normally
open) dry switch contact. Use a 22awg 2 conductor for this cable run.
Adjusting the STW1 Microphone Gain and Speaker Volume
Start with a midrange setting of the gain control on the STW1. Adjust the VR1 c or – for maximum microphone
clarity. If the sound at the DVR 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). Adjust the “talk-back” speaker volume to the
appropriate level using the blue level control located near the “70v / line” switch.
Setting the STW1 Microphone 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 STW1’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”
Available from A1 Security Cameras
www.a1securitycameras.com email: [email protected]
