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True to the Music
SIGNAL FLOW
Take a moment to follow the signal path through the block diagram below.
Return Path for 48V
Parallel Inputs
1
For fl exibility, the 8ox has three paralleled inputs.
• Female XLR connectors on the front panel
• 25 pin D-SUB (DB-25) on the rear panel
• Euroblocks screw terminals on the rear panel (Set of eight
Euroblocks terminals sold separately, Order # R800 8050).
Direct Output
2
The DIRECT output is the primary "straight through" output
and provides a return path for 48V phantom power for con-
denser microphones and active direct boxes. In the diagrams
we refer to the Main FOH console as connected to the DI-
RECT output. In fact it doesn't' matter which console, main or
monitor, is connected to DIRECT as long as it is the sole con-
sole which will supply phantom power. The DIRECT output is
paralleled to DB-25 and Euroblocks terminals for fl exibility.
Auxiliary Direct Output with Ground Lift
3
The DIRECT OUT WITH GROUND LIFT is a auxiliary output
that uses eight front panel switches to lift the ground. This
output may be patched to another audio system that may or
may not be transformer isolated itself. The DIRECT WITH
GROUND LIFT output is paralleled to DB-25 and Euroblocks
terminals.
Radial Engineering Ltd.
Inputs 1-8
DB-25
Front Panel
Ground Lift
DB-25
Euro
Block
2
Direct Output and
Auxiliary Direct Output
with Ground Lift
1
Front Panel
Inputs 1-8
XLR x 8
Euroblock
Internal
Ground
Lift
DB-25
Euro
Block
3
Isolated Output
Isolated Output
4
The ISOLATED outputs uses eight precision audio isolation
transformers to decouple the mic signals from the DIRECT
outputs. This output may be patched to a separate audio sys-
tem without creating ground loops. The ISOLATED output is
paralleled to DB-25 and Euroblocks terminals.
-20dB PAD
The front panel PAD switch can prevent transformer over-
load when connecting high output devices like synthesizers
and drum machines. Engaging the PAD reduces the level by
-20dB for that particular channel at the ISOLATED output.
Radial Transformer
After the PAD the signal is fed to the isolation transformer
where the mic signal is decoupled to eliminate noise from
ground loops. For the most fl exibility when designing techni-
cal ground systems, each transformer features an internal
switch allowing the signal ground to connect around the
transformer.
RF Filter (not shown in the diagram)
The three paralleled inputs employ a RF network fi lter on their
ground paths to prevent unused inputs from acting like anten-
nas when the ground is lifted. Any radio frequencies picked up
by an open pin will be shunted to ground.
-20dB
PAD
Isolation
Transformer
DB-25
Euro
Block
4
Transformer
8ox & 8cx Owner's Manual
3
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