TL Audio VTC - Manual (Page 46)

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4.5. MixB Outputs.
The MixB output signal path is again similar to the L+R outputs described above, except they do not
have sub-mixes or insertion points. Refer to the expanded block diagram, fig 4.
The mix amplifiers consist of IC9, 10 and 11 on PC336, feeding the valve stages on PC345 via the
signals “MIXB L VIN” and “MIXB R VIN”. The outputs from the valve stages are routed to the
MixB master level controls on PC348 as signals “MIXB L PRE” and “MIXB R PRE”, via the upper
backplane, PC355.
Refer to CD1348 sheet 2 for the MixB master level controls and output stages. The pre fade signals
from PC336 appear on PC348 as signals “BMIX L” and “BMIX R”. The “0V REF” signal
accompanies these signals from PC336, where the 0V reference is converted to the local 0V by the
difference amplifiers IC11A and IC11B. The rotary master fader is followed by +15dB gain stages,
IC9A and IC9B, and output drivers IC3 and IC4 with balance trimmers RV6 and RV7 respectively.
The MixB outputs are routed back down the IDC cable to PC355, and then out to the jacksocket PCB
or patchbay.
The MixB Assign to L+R function is accomplished by SW4, feeding into the L+R sub-mix formed
by IC7 and IC8 (CD1348 sheet 3). The signals “MIXB L” and “MIXB R” are sent back to PC355 for
monitoring by the Control Room output.
4.6. Aux Outputs.
The Aux mix busses are balanced, and linked to the input modules via the upper backplanes PC356.
The Aux mix amplifiers are located on the upper Master Backplane, PC355, linked to the input bays
by 16 way IDC cables connected to CN4 and CN5. These connectors are on the underside of PC355
and PC356, and care should be taken to ensure that they are correctly plugged in if any backplane has
been replaced. The seating of the cables linking the input bay backplanes (PC356) should be checked
if there is an apparent break in the Aux busses between bays.
The Aux mix amplifiers are entirely solid-state, and are shown on CD1355 sheet 6. Their outputs are
taken via the IDC cable at CN6 to the Aux Master modules PC347 on the upper Master Module.
Note that as for the group fader modules, the PC347s are marked PC347A for Aux 1, etc. The
circuitry is similar for all of the Aux outputs, but different pin numbers apply to the IDC connector
(CN3 on PC347) for the outputs and stereo returns which are also on the modules, hence the PC347
boards are not inter-changeable. The Aux Outputs and Stereo Returns share a common IDC cable,
which links the PC347s to the jacksocket connector PCBs, or patchbay. The cable plugs directly to
CN3 on PC347, without passing through the upper backplane.
The master stages for the stereo Aux, 7/8, are located on PC348, but are connected by the same IDC
cables. See CD1348 sheet 2.
The third IDC cable used in the upper master section is a local link between the six PC347s, PC348
and PC349. It conveys the AFL signals from the Aux outputs and stereo returns to the AFL/PFL sub-
mix on PC349, as well as the headphone mixes which are also on PC349.
4.7. Stereo Returns.
The six Stereo Returns are brought into the console from the jacksocket board, PC343, to PC347 via
the Aux/Returns IDC cable. One of the returns is processed by each of the PC347 modules. Refer to