ETS SMA1-C5, Instructions

  SMA1-C5 Speaker / Microphone Interface Instructions

 
The SMA1-C5 is a two way public address, audio surveillance interface that is designed to connect to DVRs and I/P 
cameras. The SMA1-C5 can be used with any ETS Sound Surveillance speaker/microphone with the C5 option. The 
SMA-C5 can also be used with any 70v speaker and any Sound Surveillance 

pre-amplified

 microphone with the use of 

our MIS-C5BO breakout box. The SMA1-C5 is typically located near the DVR or I/P camera. Note-input and output 
signals on the SMA1-C5 are “line level” only. 

The SMA1-C5 is for use in half duplex audio systems only.  Audio whine or 

“feedback” will be result if both speaker and microphone are active at the same time. 

Microphone / Speaker Placement. 

Locate the speaker 

and 

microphone near the area of interest in the space to be monitored. If a large area is to be 

monitored, locate the speaker 

and 

microphone in the middle of the space if possible. Avoid mounting the speaker 

and 

microphone near air conditioning vents, light fixtures or electrical equipment. The speaker 

and 

microphone

should be 

placed as close to the subject(s) as possible. 5 to 10 feet is ideal. The speaker 

and 

microphone are still useable in the 

range of 15-25 feet in public address applications but is dependent on the level of background noise in the area. 
Experimentation in the environment will determine what distances work best. 

Audio Signal Cable Runs 

Recommended cable is:  CAT5 between the SMA1-C5 amplifier / interface and the microphone/speaker (STW1-XX-C5, 
MSI-C5-BO, or HSM11-C5 or CSM8-C5). Keep the cable run distances under 1,000 feet and away from AC power 
sources, light fixtures and electrical equipment.

 Make connections as shown in Figure 1.  

 
IMPORTANT 

Wire the RJ45 connectors in the following manner. DO NOT wire as a standard Ethernet cable and do not cross 
connections over. 
 
Pair 1   

1  

CALL SW 

2  

CALL SW 

Pair 2   

3  

SPEAKER (70V) + 

4  

SPEAKER (70V) – 

Pair 3   

5  

MICR 

6  

MICROPHONE – 

Pair 4   

7  

+12V (MICROPHONE) 

8  

COM (MICROPHONE) 

 
SMA1-C5 location and power: 

The SMA1-C5 interface box is designed to be located next to a DVR or I/P camera. The 

SMA1-C5 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 
SMA1-C5. 

DVR or I/P camera connections: 

Connect the “audio out” of the SMA1-C5 to the “audio in” of the DVR or I/P camera. Connect the “audio in” of the SMA1-
C5 to the “audio out” of the DVR or I/P camera. Note-input and output signals on the SMA1-C5 are “line level” only. If the 
DVR or I/P camera uses screw terminals for audio connections, simply cut off the ends of the supplied RCA patch cables, 
strip the wires back and connect the wires to the I/P camera terminal blocks. The center conductor of a cut patch cable is 
+ and the shield is -. 
 

Adjusting the SMA1-C5 Levels: 

Set both level controls to 1/8 clockwise from full counter clockwise on the SMA1-C5 before powering the system up. 
Adjust the co or – to the desired levels for both speaker and microphone. If the microphone sound at the DVR or 
head end is distorted, rotate the control towards the – mark (counter- clockwise). Adjust the volume of the speaker to the 
desired level. If the speaker volume is too high, amplifier oscillations may result. Turn the level control down if you 
experience this.