Operating instructions

(+)
(-)
CONSOLE
LINE INPUT
(+)
(-)
SHIELD
CHASSIS
GROUND
Zin > 10k
ohms
OUTPUT
ELECT GND
560 ohm TYPICAL
MATCHING RESISTOR
600 ohm
MATCHING RESISTOR
UNBALANCED
AUDIO
SOURCE
ISOLATION
TRANSFORMER
3-3f) UNBALANCED SOURCE OUTPUT THROUGH AN ISOLATION TRANSFORMER TO BALANCED
CONSOLE INPUT
In some situations an Isolation Transformer is required to solve tough RF Interference or ground loop problems where the Source
Output is unbalanced. The Isolation Transformer must be impedance matched to both the source and the console .
Typically a 600 ohm audio transformer is used whose inputs and outputs want to see a fixed impedance of 600 ohm for it to meet
frequency response and distortion specifications. The Console Input is high impedance (>10,000 ohms). To match impedances,
a 600 ohm resistor must be placed across the input of the console as shown below.
Most unbalanced sources are low impedance but not all. Check the Zout spec of the source device to insure the proper matching
resistors are placed in series with the transformer primary leads. The total resistance, Zout + Zseries, should equal 600 ohm for a 600 ohm
transformer. Different transformers and resistors may have to be used for proper impedance matching.
Arrakis Systems, inc. --- 6604 Powell st., Loveland, CO 80538 --- 970-461-0730 --- www.arrakis-systems.com
INSTALLATION PROCEDURES
INPUT WIRING (continued) 3-3)
3.11