Studio Technologies 770 - Manual (Page 29)

Model 770 User Guide Issue 1, October 1997
Studio Technologies, Inc. Page 29
Model 770
function!) In the off (out) position the filter
is not placed in the audio path, leaving
the signal essentially “flat.” In the on (in)
position the signal is routed through the
filter circuit, removing low-frequency
energy.
The filter is useful for eliminating wind
noise, traffic rumble, and AC mains hum.
It was carefully designed to give a steep
slope (18dB/octave), with the –3dB point
at 85Hz. For most voice applications the
filter can be left activated. For wide-band-
width signals, such as music, the filter
should be used only as necessary.
Changing the on/off status of the low-cut
filter will result in little or no noise being
added to the audio signal. While it is better
to set the filter’s button to the desired
position prior to being “live,” it can cer-
tainly be used at any time.
Status LED
A bi-color LED acts as a user-confidence
indication of the overall signal level in the
mic/line input channel’s circuitry. The LED
will light with the color green as a signal
present indicator, showing that the input
signal, along with the gain of the input
preamplifier, is at least 18dB below the
nominal internal operating level. The LED
will light with the color red as a peak
signal indicator, showing that the input
signal, along with the gain of the preampli-
fier, is within 6dB of the circuitry’s maxi-
mum level.
Level Control
The rotary control is used to adjust the
gain of the input preamplifier circuit. In the
fully counterclockwise position the pream-
plifier gain is set to its minimum, and full
attenuation is achieved. This means that
no signal continues on to the next stage
of the mic/line input circuitry and, if config-
ured, to the configurable output on the
back panel. As the level control is rotated
in the clockwise direction the gain of the
preamplifier increases.
Bus Assignment
Located below the level control are two
buttons, labeled MAIN and AUX. These
buttons control the connection of the
audio signal to the main and AUX audio
buses.
Main Bus Assignment
The button labeled MAIN controls the
assignment of the audio signal to the main
audio bus. In the off (out) position, signal
is not connected to the main bus; in the
on (in) position, the signal is connected
to the main audio bus.
AUX Bus Assignment
The button labeled AUX controls the
assignment of the audio signal to the AUX
audio bus. In the off (out) position, signal
is not connected to the AUX bus. In the on
(in) position, the signal is connected to the
AUX audio bus.
Stereo Line Inputs
The Model 770 contains two identical
stereo line input channels. They are
unique in that the left and right signals
associated with each stereo input are
automatically mixed to monaural, by way
of level controls, in preparation for assign-
ment to the mono mixing buses. The input
circuitry was designed for compatibility
with signals that have a nominal level of
+4dBu. However, nominal signal levels
of –10 to +10dBu are perfectly accept-
able. A description of one of the stereo
line input channels is provided.