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Output driver stage
The output driver stage consists of four
OPA2134 dual channel Op-Amps (IC400-
IC403) each output for instance Front left
channel takes one channel of the op-amp.
The front left and front right channels are
driven down into the Pre-amp board via Pins
1 and 2 of connector Con400 and is fed into
the input switches of the Pre-amp boards
multiplex on Pin 9 from this point the signal is
dealt with as a normal signal input into the
Pre-amp.
Please note: the left and right signals are
seen on the L937 pre-amp card circuit
diagrams as module left and module right.
The Remaining channels are rail clamped to
remove any over-voltage spikes from the rails
and to prevent damage to ancillary equipment
using diode packages D400 – D405.
Each output has a mute relay that when
engaged shunts the output to ground at
power up and power down preventing any
spurious D.C levels from leaving the card.
Simplified Block Diagram
6
8
8
2
2
Micro controller
From Host micro controller
Volume
6
Buffer
Volume
2
Buffer
Mute
6
Buffer
2
Buffer
Centre, Sub, Surround
L+R, Back L+R out
Front Left and Right
to host.
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