Studio Technologies 81 - Manual (Page 11)

Model 81 User Guide Issue 1, January 2000
Studio Technologies, Inc. Page 11
As soon as mains power is connected, the
Model 81’s power present LED will light.
The unit is now ready for years of trusty
service!
Configuration
Input Level Calibration
With the ExactCal calibration section it’s
simple to match the nominal level of the
input signal with the Model 81’s internal
circuitry. Two 15-turn trim potentiometers,
along with four LEDs, form the ExactCal
section. One trim pot is associated with
the left input, the other with the right. Two
LEDs, labeled Lo and Hi, are associated
with each input. They are provided as an
aid to calibration, as well as serving as
“signal present” indicators.
The following is a step-by-step procedure
for using the ExactCal section to match an
input signal to the Model 81's circuitry:
• Set the trim pots to their fully counter-
clockwise position. Remember, the
trim pots are 15-turn type, so you may
have to rotate them up to 15 times
before reaching their fully counter-
clockwise position.
• Supply a 1kHz sine wave to both the
left and right inputs. Set the level of the
source to be precisely the nominal
operating level. If, for example, the
output of a console is connected to
the input of the Model 81, the console
output should be adjusted so that the
meters read 0dB or 100%. If the output
of the console is a “+4-type,” then
setting the console’s left and right
output levels to nominal should find
the console output levels to be exactly
+4dBu.
• Slowly turn the trim pot associated with
the left input in the clockwise direction.
As you increase the level, watch the
LEDs associated with the left channel.
The LED labeled Lo will light first, then
both LEDs will light, then only the LED
labeled Hi will light. The correct setting
is where both LEDs light their brightest.
Careful adjustment is required as the
“window” where both LEDs light is
somewhat less than 1dB.
• Repeat the above procedure for the
trim pot and LEDs associated with
the right input. When the configuration
is correct both LEDs associated with
the right channel input will be lit to their
brightest.
• Disconnect the 1kHz signal and con-
nect the normal audio source.
Output Level Selection
Each of the eight stereo line-level outputs
is individually configurable for a –10dBV
or +4dBu nominal output level. Eight DIP-
type switches, located on the right side of
the front panel, are used to set the output
levels. The legend on the switches corre-
spond to the output channel numbers. A
switch that is set to its up position config-
ures its associated output channel for
–10dBV. A switch set to its down position
configures the output for +4dBu. A small
screw driver may be of assistance when
setting the switches.
Operation
Now that you’ve installed and configured
the system, you’re ready to go. You
should find operation very easy, as there
is nothing to do on a day-to-day basis. For
peace of mind, the ExactCal LEDs will give