TL Audio VTC - Manual (Page 45)

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4.4. Group Outputs.
Refer to the expanded block diagram, fig 2. The Group mixes and outputs follow a similar path to the
L+R outputs described above.
The sub-mix for the groups consists of just the Talkback and Oscillator signals, routed onto PC336 as
“TAPE +” and “TAPE -”. The mix amplifier for Group 1 is formed by IC3 and IC4A (see CD1336
sheet 2), and the valve stage on PC345 (“G1 VIN”, returned as “G1 VOUT”). After the insertion
send, the return is routed to the Group 1 fader module, PC338A, as “G1 FDR” on CN4. The buffered
post fade signal “G1 WPR” is routed to the output stage on PC355, and also back along the PC337
backplanes for selection by the input modules’ “BUSS” switch. PC338A also contains switches for
routing the group signal to the L+R mix and AFL monitoring.
Groups 2 to 8 have similar circuitry, but note that the group fader modules, PC338, are not
interchangeable. They are identified as PC338A for Group 1, PC338B for Group 2, through to
PC338H for Group 8. The circuitry differs for the L/L+R or R/L+R routing on odd and even groups
respectively, and the pin numbers for the pre and post fade signals on the IDC cable.
The group output signals are monitored by the meter controller on PC355 (“MTR G1”, etc), and have
a jumper programmable nominal output level - see CD1335 sheet 2. The default output level is
+4dBu, but may be changed to -10dBu by fitting J14 for Group 1. The jumper identifications on
PC355 for all of the groups are shown in table 2:
Table 2: Group Output level jumpers.
Located on PC355. Fit jumper to convert to -10dBu.
Group
1 J14
Group
2 J10
Group
3 J13
Group
4 J9
Group
5 J12
Group
6 J8
Group
7 J11
Group
8 J7