Studio Technologies 742A - Manual (Page 21)

Model 742A User Guide Issue 1, July 2012
Studio Technologies, Inc. Page 21
Audio Mixer
Level Meters
Two 10-segment LED meters display the
level present on main outputs 1 and 2.
Each meter has seven green LEDs which
light in the presence of signals in the
normal operating range. Two yellow LEDs
light with signals slightly higher in level
than normal. One red LED lights when-
ever the signal level is in the “headroom”
area. The ballistics of the meters is a cross
between that of VU and a peak (PPM)
meters. (We affectionately refer to them as
“PU” meters!) The way the LEDs “move”
in response to signals should be comfort-
able for most users to observe.
While the meters are easy to interpret,
they are somewhat different from ones
that are marked with “VU” nomenclature.
The important thing to remember is that
the steps show level in dBu, rather than
VU units. So, for example, when the meter
step that is labeled “0” lights, it indicates
that 0 dBu is present on its associated
main output connector. It doesn’t indi-
cate 0 VU! (Remember that 0 VU typically
indicates a device’s reference operating
level—often +4 dBm.)
The seven green LEDs in each meter
display a dynamic range of 28 dB, with
thresholds of –24 dBu, –18 dBu, –12 dBu,
–8 dBu, –4 dBu, 0 dBu, and +4 dBu. This
is the range that typical signals should
display if correct settings have been made
to the input sensitivity switches, input level
controls, and master level controls. The
two yellow LEDs light when a signal level
has exceeded the Model 742A’s nominal
+4 dBu output level. Their thresholds
are +8 dBu and +12 dBu, well within the
capabilities of the unit’s circuitry. The red
LED will light when signal on the main
output meets or exceeds +18 dBu. This
is dangerously close to the Model 742A’s
maximum output level and should be
avoided.
But now back to reality when it comes to
how the meters will function during actual
Model 742A use. To a great degree meter
activity will depend on how the compres-
sors have been configured to operate.
As discussed in previous sections of this
user guide, a technician can set the Model
742A’s compressors to operate from one
of three modes:
Figure 15. Detail of front panel highlighting master level controls, 10-segment LED level meters, and
compressor active LEDs