Audio Developments AD 245, Manual, Page: 21 / 26

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Line-up tone, when selected (8), replaces the normal signals on the main output.
The frequency of the line-up tone may be selected between 1kHz and 10kHz (9).
Line-up tone is calibrated on the (BBC-scaled) meters to PPM4, giving a line-output
level of 0dBu with the output faders set to maximum.
The remaining controls are associated with headphone-monitoring of signals from the
mixer - internal signals (DIR) or tape-return (RET) may be selected (13): these signals
may be either in the L-R domain or the M-S domain. When switches (13), (14) and
(15) remain unselected the main-output signal from the mixer appears on the
headphones. If SW (14) is selected, the left-output signal appears on both earpieces;
if SW (15) is selected, the right-output signal appears on both earpieces. If switches
(14) + (15) are selected, a matrix amplifier is inserted across the monitor output:
when the main output is in the L-R domain, the matrix will enable mono compatibility
to be assessed on the left earpiece and out-of-phase components to be checked on
the right earpiece. When working entirely in the M-S domain, the matrix will transform
the mixer output into the L-R domain for monitoring purposes. Selection of RET (13)
will allow these functions to be performed on a tape-return signal. The level of the
monitor signal is controlled by potentiometer (16).
A mono mixdown of the main, stereo output from the mixer is available and its level is
adjusted by MONO (17).
The signal from the internal microphone (18) replaces any other signal appearing at
the outstation when routed via EXT (20) - the level being set by preset GAIN (19).
SLATE (21) allows the mixer operator to ADD a voice signal to the main stereo output
together with a low-frequency identification tone (100Hz).
When PFL is selected on an input channel or when the outstation wishes to
communicate with the mixer operator (by grounding pin 6 on the multiway), logic
changes the signal on monitor output accordingly.