Studio Technologies 76B 2008 - Manual (Page 16)

Issue 1, July 2008 Model 76B/77B User Guide
Page 16 Studio Technologies, Inc.
for Surround
coffee cups! But a fi rm press with the fl eshy
part of an index fi nger should do the trick.
There is no problem frequently “tweak-
ing” the system’s operating parameters
to achieve the desired performance. The
confi guration data is stored in nonvolatile
memory, which is rated for thousands of
read and write cycles and a retention time
in tens of years. Note that memory inte-
grated circuits are located in both the Model
76B Central Controller and the Model 77B
Control Consoles. Only the individual device
address is stored in each Model 77B. All
other confi guration para-meters are stored
in the Model 76B.
Model 77B Device Address
A unique device address must be assigned
to each Model 77B that is connected to a
Model 76B. The choices are A1, A2, A3, or
A4, with the default address being A1. As
most installations will fi nd only one Model
77B utilized, its default setting is appropri-
ate. For installations that use a second,
third, or fourth Model 77B each unit must
be confi gured with a unique device address.
Problems will occur if more than one unit
has the same address! It’s important to
highlight the fact that the device address is
the only setting that must be done on each
individual Model 77B unit. All other settings
can be made on any one of the connected
Model 77B units.
Auxiliary Output Nominal
Level
The nominal level of the stereo (2-channel)
auxiliary output can be confi gured to match
the requirements of a specifi c installation.
Devices connected to the auxiliary output
could include an amplifi er associated with
a loudspeaker system or inputs on self-
contained amplifi ed loudspeakers. (These
types of devices must include a means of
adjusting their output level.) This confi gura-
tion setting defi nes the analog output level
when a digital input source, at its refer-
ence level, is connected and the auxiliary
output is enabled. The choices are +4.0,
0.0, –6.0, or –12 dBu. When connecting to
the input of a device that’s not associated
with a loudspeaker system most applica-
tions will fi nd the +4.0 dBu setting correct
as it meets the dominant worldwide audio
standards. For broadcast applications
that follow the PAL standards the 0.0 dBu
setting may be appropriate. Devices such
as amplifi ed speakers will often perform
better when receiving signals with a lower
nominal level. In the latter case the ability
to comfortably use a level potentiometer
may be greatly enhanced using the –6.0 or
–12.0 dBu settings. The latter setting would
be appropriate when connecting the auxil-
iary output to the popular series of ampli-
fi ed loudspeakers from Fostex®.
While sometimes not fully understood,
using the term dBu is more in line with
contemporary audio applications than
the outdated dBm and the “semi-pro”
dBV references; dBu refers to audio levels
without regard to their load impedance,
typical of situations where an output has a
low source impedance and is connected to
a high-impedance input. An analog audio
signal with a level of +4 dBu has an RMS
level of 1.228 volts. A 0 dBu signal has an
RMS level of 0.775 volts.
Digital Input Reference Level
Confi guring the digital input reference level
to match the sources associated with a
specifi c installation is an important step