Studio Technologies 55 1996 - Manual (Page 30)

Issue 3, December 1996 Model 55/56 User Guide
Page 30 Studio Technologies, Inc.
operating, the current operating param-
eters are saved in nonvolatile memory
and the Model 55 Central Controller will
continue to operate as it did when the link
was broken. No clicks, pops, or other
noises will occur when the Model 56 is
again connected.
The Model 56 will go through its standard
power-up sequence, send a message to
reset power-up defaults, then send the
operating parameters as stored in its
memory. You may notice a brief interval
of silence while the Model 55 responds
to the reset defaults message.
Control Room Mono Function
Many arguments where had while design-
ing the control room monaural function.
Was the function supposed to be a true
mono function, sending the sum of left
and right to a separate mono control room
output? Was mono to be the sum of left
and right sent to both left and right chan-
nels? What about level build up with
phase coherent signals that are in both
the left and right channels? After much
head scratching it was realized that the
mono function that most people are ac-
customed to is really a means of observ-
ing the character of a stereo mix, and not
a “true” mono function. To observe the
stereo image of a mix you need to sum
the left and right signals, drop the level of
the sum by 6dB, and send the result out
the left and right outputs. This is what
virtually all recording consoles implement,
and is what the StudioComm does, too!
Talent Amplifier Mono Function
The Model 35 and Model 38 Talent Ampli-
fiers each contain a monaural switch. The
mono function sums the left and right input
signals, drops the level of the sum by 6dB,
and sends the sum to both the left and
right outputs. This is consistent with the
mono methodology discussed in the previ-
ous paragraph. Please refer to that note
for details.
Input Level and the Talent Amplifiers
Optimal performance of the Model 35 and
Model 38 Talent Amplifiers depend on the
headphone source signal levels being at
approximately the nominal input level,
either –10dBV or +4dBu, depending on
the configuration. The headphone volume
is adjusted only by the level controls on the
talent amplifiers. If the selected headphone
source signal level is significantly less than
nominal, the talent amplifier will simply not
be able to create the maximum volume in
the headphones. While there is some gain
in the talent amplifiers, optimal perfor-
mance still requires an input close to
nominal.
The Model 38 Talent Amplifier can also
exhibit reduced performance if the level
of the headphone source is significantly
“hotter” than nominal. The entire system
has plenty of headroom, but maintaining
proper signal levels, as usual, is important.
If the source selected for headphones has
an average level that is excessive, a small
amount of bleed-through can be heard with
the Model 38’s cue mix level control set
fully counterclockwise. Instead of having
no sound in the phones, a bit of sound can
be heard. This is not a design problem; the
Model 38 has a sensitive preamplifier
section which doesn’t like excessive excur-
sions in the left channel modulation of the
+23Vdc signal. The Model 38’s power
supply can reject the left channel modula-
tion within the design parameters, creating
a clean reference voltage for the stereo
preamplifier. Modulation levels outside