artist manager have the same facilities. The independent pair of contacts in the
Artists Manager’s microphone is used to operate active relay RL3 to quiet the
control room monitor loudspeakers and to operate active relay RL4 to switch the
Amplifiers N from normal signal to talkback.
8.3.8 R.F. Suppression
The microphone connections constitute leads entering the Mixer at low level
with no input transformers and no Band Pass Filters. In order to minimise the risk of
these leads introducing r.f. interference, these inputs are shunted by capacitors,
0.1
µ
F in the case of the 25
Ω
microphone and 0.022
µ
F in the case of the 200
Ω
microphone.
8.4
Alternative Talkback
At the right hand side of the panel beyond the Studio Talkback Loud button is
a 3-position key. In its central position marked Studio LS the talkback system
operates as described above. In both the other positions the signal from the
Amplifier A3 (B21) is disconnected from the Studio Talkback Normal level control
and connected to VR 8 marked ALT T/B Level on the block schematic diagram.
This is a screwdriver operated control located just in front of the key which brings it
into circuit. This control feeds a normal line output circuit consisting of an Amplifier
R and output transformer the output of which is available on pins 4 and 5 of 5-pin
Tuchel socket SK2 for feeding to a power amplifier and loudspeaker.
In the forward position marked ALT a pair of contacts on the key is used to
break the energising supply to RL4 thereby preventing it from being energised so
that the signal to the studio loudspeakers is unchanged.
The backward position is marked ALT (M), the (M) indicating that the studio
speakers are muted. This is realised by allowing RL4 to operate, thereby feeding
the studio loudspeakers from the talkback line, but as the signal has been removed
from this line, the loudspeakers are muted.
8.5
Intercom
This allows the operator to talk to another location, possibly a remote
machine room.
Signal from the output of the Amplifier A3 (B9) can also be switched by a key
located to the left of the alternative talkback key, through a preset level control in
front of the key to another Amplifier R and output transformer. The output is
available at line level on pins 1 and 2 of SK2.
8.6
Cueing
8.6.1 Operator to Cue
By operating the intercom key in the reverse direction, which is marked OP to
Cue, signal is applied to two level controls with “off” positions. These controls are
marked CUE 1 and CUE 2 and they allow signal to be routed through Amplifier B to
the cue bus lines.
