4.5
Power Supply
The Power Unit is identical with that used on the Microphone Cassette. The
Group Cassette consumes about 57mA at +20V and 93mA at –20V.
5.
MAIN CASSETTE
5.1
Contents
Each Main cassette contains two identical main channels, the signal
in each of which can also be fed, if desired, to an auxiliary stereo channel
and to the two cue channels.
5.2
Main Channel
5.2.1 Input Gain Control
Each input is a main channel bus line. As in the case of a Group
Cassette input, it is desirable to have a gain control. An input circuit consisting of an
amplifier C1 with a feedback control giving a range of
±
10dB in 2dB steps is
therefore provided.
5.2.2 Inject
This facility is identical with that provided in the Microphone and Group
cassettes (See 3.5.3).
5.2.3 Fader
Faders with optional ganging are provided as in the Group Cassettes (See
4.2.4).
5.2.4 Poling
In order to maintain correct overall polarity a phase reversal is required so, as
in the Group Cassette, an Amplifier K is used to provide this and the 5dB gain
necessary to counteract the 5dB loss of the fader at its normal working position.
5.2.5 Presence Controls
These are identical with those used in the Microphone and Group Cassette.
5.2.6 Band Pass Filter
This again is similar to that used in the Microphone Cassette. Since in this
case it is followed by a switch, an output a.c. coupling C2, R1 (C4, R2 in the right
channel) is provided.
5.2.7 Track Announce – Individual
For announcement on an individual track, each channel has a push button
with change-over contacts which transfer the input of the subsequent amplifier from
the output of the Band Pass Filter to the track announce signal bus line, and make
