Studio Technologies 78 2004 - Manual (Page 13)

Model 78/79 User Guide Issue 5, January 2004
Studio Technologies, Inc. Page 13
for Surround
As soon as AC mains power is applied, the
Model 78’s power present LED will light.
The Model 79 will go through a power-up
sequence, lighting each LED in secession.
The Model 79’s software revision level will
also display momentarily. The data active
LED on the Model 78 will briefly light upon
completion of the Model 79’s power-up
sequence.
Configuration
After the physical installation has been
completed, several configuration issues
must be addressed. On the Model 78 the
surround inputs must be calibrated using
the trim potentiometers. The operating pa-
rameters of the system should be set using
the Model 79 Control Console’s configura-
tion mode. Using the Model 79’s calibration
mode, output channel level offsets can be
configured if desired.
Input Level Calibration
Sixteen 15-turn trim potentiometers are
located on the front panel of the Model
78 Central Controller. Taking time to care-
fully adjust the trim pots will ensure that
accurate monitoring can take place. Each
trim pot allows input signals with a nominal
level of –12 dBV to +6 dBu to be utilized.
With care, it’s easy to calibrate the sur-
round inputs to within one-quarter of a dB
of the desired value.
The monitor outputs are used as the mea-
suring point when adjusting the trim pots.
A laboratory-grade audio level meter,
or equivalent, is required for accurate
calibration. In addition, the audio sources
connected to the inputs must be able to
generate continuous audio signals at their
nominal operating level.
Procedure
This procedure will calibrate the surround
input channels. The trim pots will be ad-
justed in groups corresponding to their
associated input source.
1. Begin by turning the audio amplifiers
or amplified speakers to their off state.
This will protect the loudspeakers and
the operator’s ears from possible
damage.
2. Rotate the level control on the Model
79 to the fully clockwise (maximum)
position.
3. Using the Model 79 Control console,
select Surround A as the input source.
4. On the Model 78, connect the audio
level meter to the left channel of the
monitor output.
5. Confirm that the audio source’s left
channel is generating a steady signal
at precisely its reference level.
6. Observing the level meter, adjust trim L
for Surround A to give the desired level
at monitor output L. This level may be
+4 dBu, +14 dBu, or some other value
depending on the configuration of the
output level range.
7. Disconnect the level meter from the left
channel of the monitor output.
8. Repeat steps 4-7 for the other seven
channels of Surround A.
9. Repeat steps 3-8 for the channels as-
sociated with Surround B.
10. Rotate the level control on the Model
79 to the fully counterclockwise (mini-
mum) position.