Studio Technologies 55 2002 - Manual (Page 29)

Model 55/56 User Guide Issue 4, June 2002
Studio Technologies, Inc. Page 29
desired cable length. There are too many
variables to give a simple formula—good
luck!
Definition of Level—dBu and dBV
Whenever possible, Studio Technologies
has opted to use the dBu designation as
it seems to be quite rational. Using dBm
was fine when all audio line outputs were
terminated with 600 ohm loads. In this
way it was easy to say that 0dBm is 1
milliwatt dissipated in the known load (i.e.,
0dBm across 600 ohms will measure
0.775V). In contemporary situations an
output is rarely terminated with 600 ohms;
generally 10k ohms or higher. The dBu
designation is better because it refers to
dB referenced to 0.775V, with no refer-
ence to load impedance. This takes into
account today’s audio scene where sig-
nals have a low source impedance, and a
high input impedance. The dBu designa-
tion is becoming the standard for the
professional audio industry.
StudioComm equipment is designed to
interface with audio signals that have
nominal signal levels of –10dBV and
+4dBu. You might wonder why dBV
came into the picture. Most people
don’t realize that equipment that utilizes
“–10” levels usually mean –10dBV —
substantially different from –10dBu
(–10dBV = –7.78dBu). The dBV designa-
tion is simply a different way of measuring
signal level and is often used when dealing
with portable or consumer audio equip-
ment. The dBV designation refers to dB
referenced to 1.0V, rather than dBu which
refers to 0.775V.
“Hot” Disconnection of the Model 56
Control Console
Should you need to relocate the Model 56
while your StudioComm system is operat-
ing, there is no reason why you can’t
disconnect the 5-conductor cable, move
the unit, and then connect it again. If
the Model 56 is disconnected while it is
operating, the current operating param-
eters are saved in nonvolatile memory and
the Model 55 Central Controller will con-
tinue 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 accustomed
to is really a means of observing 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, and send