Studio Technologies 742A - Manual (Page 19)

Model 742A User Guide Issue 1, July 2012
Studio Technologies, Inc. Page 19
Audio Mixer
If phantom power is enabled for a channel
it is only active when the channel’s mic/
line input sensitivity switch is set to its mic
(out) position. Phantom power is not avail-
able in the line position. Note that when
phantom is selected for an input channel
it’s normal for a slight “click” or “pop” to
be heard when moving that input’s sen-
sitivity switch between the mic and line
positions, and vice-versa. This noise, while
slightly annoying, will not harm the cir-
cuitry. It also provides an aural indication
that phantom power is available. (It’s not a
technical limitation, it’s a feature!)
Status LED
A dual-color LED acts as a user-confi-
dence indication of the overall signal level
in the mic/line input channel’s circuitry.
The LED will light green as a signal pres-
ent indicator, showing that the input
signal, along with the gain of the input
preamplifier, is at least 18 dB below the
nominal internal operating level. The LED
will light red as a peak signal indicator,
showing that the input signal, along with
the gain of the preamplifier, is within 6 dB
of the circuitry’s maximum level.
Level Control
The rotary control is used to adjust the
gain of the input section’s preamplifier
circuitry. It also controls the amount of
signal that can be sent to the output bus
(or buses). In the fully counterclockwise
position the preamplifier gain is set to its
minimum, and full attenuation to the bus
(or buses) is achieved. This means that no
signal continues on to the mixing circuitry
that creates the main outputs. As the level
control is rotated in the clockwise direc-
tion the gain of the preamplifier increases,
as does the level of the signal sent to the
selected output bus (or buses).
Output Assignment Switch
A 3-position toggle-type switch is used
to assign which of the output buses the
signal will be routed to. In the “up” posi-
tion the signal is sent only to output bus
1. In the “down” position the signal is sent
only to output bus 2. In the “center” posi-
tion the signal is sent to both output buses
1 and 2.
Line Inputs
Four identical line-level input channels
are provided. (Refer to Figure 14 for a
detailed view of one of the line input
channel sections.) The following provides
a detailed description of one of them:
Status LED
A dual-color LED acts as a user-confi-
dence indication of the overall signal level
in the circuitry associated with the line-
level input. The LED will light green as a
signal present indicator, showing that the
input signal, along with the gain or loss of
the input amplifier, is at least 18 dB below
the nominal internal operating level. The
LED will light red as a peak signal indica-
tor, showing that the level is within 6 dB of
the circuitry’s maximum.
Figure 14. Detail of front panel showing one line
input channel (typical of four)