8.2
Loudspeaker Channels
8.2.1 Input Selectors
Each channel has an input selector with positions identical with those of the
monitor selectors in the Control Room Monitor Cassette (Section 7.2.3).
8.2.2 Level Controls
The outputs of the input selectors are passed through Band Pass Filters and
coupling capacitors to level controls. Since the two channels may be used to
handle unrelated signals, independent controls are provided. Electrically these are
similar to the twin control used in the Control Room Monitor Cassette but they are
calibrated from +10dB to –30dB.
8.2.3 Pole
The facility of reversing the polarity of the right hand channel by means of a
spring return push button is provided as in the Control Room Monitor Cassette. As
the facilities for the solo feature are not required in the studio playback circuits, the
Amplifier H is used which is a simplified form of Amplifier P. Amplifier H is
described in 12.10.
8.2.4 Loudspeaker Switch
This is identical with that used in the Control Room Monitor Cassette (section
7.2.7).
8.2.5 Studio Talkback
In order to provide for the replacement of normal signal by talkback, a
switching Amplifier N is included in each channel, this being the amplifier used in
the Main Cassettes for switching track announce. The control signals for switching
the Amplifiers N are supplied by active relay RL4, the operation of which is
described in 8.3.
8.2.6 Output
The output circuits consist of Amplifiers R and output transformers with a 5-
pin Tuchel output socket as used for echo outputs in the Group Cassette (section
4.3.2).
8.2
Talkback
8.3.1 Operator’s Microphone
The Studio Playback Cassette has no meter associated with it so its meter
space in the frame is used for the microphone for the operator. It is a 200
Ω
moving
coil type and it is provided with a 6-pin miniature Tuchel plug on a flying lead, a
mating socket SK7 being provided on the cassette.
