Installation
Connections
The SMR™821a is designed to be installed in a standard EIA equipment rack. Since the depth of the unit is only 8 3⁄4"‚ you can use practically any size rack. Using only a single EIA rack space‚ the SMR 821a includes integral rack mounting ears and does not require any additional hardware for rack mounting…other than rack screws!
All connections are made on the rear panel. It is recommended that you provide an additional 4" of clearance between the rear of the chassis and the interior rear of your equipment rack for wiring harnesses. Since every connection to the SMR 821a is easy to disconnect‚ the unit can be removed from an equipment rack easily‚ without having to disturb fixed wiring harnesses.
Using common sense when installing this unit will help ensure that it will provide years of trouble- free service. In installations where there are multiple power amplifiers‚ it is also recommended that the SMR 821a be located more towards the top of the rack‚ while power amplifiers remain near the bottom. This is generally considered standard rack design in the commercial audio industry. Following this convention will ensure adequate rack cooling‚ proper weight distribution and reliable operation from the SMR 821a.
Connecting the SMR 821a is not much different than any other analog audio device. In addition to the normal inputs and outputs‚ there are also external control ports and bus link connectors.
Note: All cables for these connections should be shielded. Refer to the following illustrations for each type of connection.
Audio Inputs
The inputs to the SMR 821a are balanced. This means there are three wires for each connection: positive; negative and shield. These should be connected to each pin accordingly.
Figure 1. Balanced Audio Input Connections: Microphone or Line Level
Shield
Audio Negative
Audio Positive
Figure 2. Unbalanced Audio Input Connections: Microphone or Line Level
Insert jumper wire between the negative and shield pins for unbalanced circuits
Shield
Audio “Hot” or Positive
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