SoundCraft DC 2020, User Manual

Page: 64 / 190

Oscillator and Talkback Panel
Power Indicators
1
There are four LEDs which indicate the presence of power on power rails within
the machine. They are 48V, 17V, 12V and 5V
Oscillator
The Oscillator is used to set signal levels at the tape machine. This oscillator isn’t
to be confused with the Slate Oscillator which is used for marking the tape.
2
The sine wave oscillator is switchable between 1kHz and 10kHz.
3
The OSC control adjusts the level of the oscillator signal: it has a maximum of
10VU.
4
Pressing the CAL switch fixes the level at 0dBu at the mix output, this level is
adjustable via the preset pot which is accessible through the small hole near the OSC
pot.
5
The TAPE switch routes the oscillator signal to the SLATE bus and also
activates the Slate Enable (SLATEN) bus: this causes all the Input Modules to switch
their Tape Sends to the Oscillator signal. The MIX switch adds the Oscillator signal
to the MIXL and MIXR buses. The LED between the TAPE and MIX buttons glows
if either of these switches are pressed.
Talkback
The Talkback system includes the Slate Oscillator: the nominal frequency of the
tape oscillator is 25Hz.
6
The GAIN pot controls the amplification of the inbuilt mic Talkback Ampli-
fier.
7
The inbuilt microphone.
8
When the TAPE switch is pressed the Slate Oscillator is switched on. Its output
is summed with the output of the Talkback Amplifier. The summed output signal
is routed to the SLATE bus and is also summed with the MIXL and MIXR buses;
the routing is done via the TAPE and MIX switches in the Oscillator section, so
pressing either of these will override the talkback to their respective destinations.
The SLATEN bus is also activated: this causes all the Input Modules to switch their
Tape Sends to the Slate Osci Talkback signal.
The Control-room phones/speakers signals are attenuated by a nominal 20dB when
the TAPE switch is pressed.
9
When the Talkback to STUDIO SPeaKeRS switch is pressed the signals to
Studio Speakers are attenuated by 20dB (nominal) and the talkback signal from the
in-built mic is added to the attenuated signal.
The Control-room phones/speakers signals are also attenuated by a nominal 20dB
when the STUDIO SPEAKERS switch is pressed.
4.24 DC2020 Oscillator & Talkback Panel