Studio Technologies 742 2005 - Manual (Page 24)

Issue 2, May 2005 Model 742 User Guide
Page 24 Studio Technologies, Inc.
Model 742
Compressor Configurations
The compressor circuits that control the
dynamic range of the main output buses
can be configured to operate from one
of three modes. Two configuration jump-
ers, one for each compressor circuit, are
used to select which mode is active. From
the factory the jumpers are placed across
the pins labeled +10 dBu. This sets the
thresholds to be 6 dB above the main out-
puts’ +4 dBu nominal output level. Mov-
ing the jumpers to the +6 dBu positions
sets the thresholds to be 2 dB above the
+4 dBu nominal output level. To disable
compressor operation place the jump-
ers on the pins labeled OFF. Finding the
compressor configuration locations is not
difficult. When viewed with the cover off,
they are located at the back of the printed
circuit board, near the XLR-type connec-
tors that are associated with the main
outputs. The jumper sections are labeled
COMPRESSOR 1 and COMPRESSOR 2.
The factory default has the jumpers set to
their +10 dBu positions.
Monitor Output Configurations
The monitor section’s line-level outputs
are configured to operate from one of
three modes. Two configuration jumpers,
one for each monitor output, are used to
select the desired mode. From the factory
the jumpers are placed across the pins
labeled POST. This configures the moni-
tor outputs so that they are after (“post”)
the level controls. Moving the jumpers to
the PRE –10 locations sets the monitor
outputs to be electrically before (“pre”) the
level controls and to have a nominal level
of –10 dBu. This is appropriate when con-
necting the monitor outputs to the inputs
of most amplified loudspeakers. Moving
the jumpers to the PRE +4 locations sets
the monitor outputs to be “pre” the level
controls but with a +4 dBu nominal level.
This mode allows the monitor outputs to
serve as an additional set of line-level main
outputs. Finding the configuration loca-
tions for the monitor outputs is not difficult.
When viewed with the cover off, they are
located at the back of the printed circuit
board, near the XLR-type connectors that
are associated with the main outputs. The
jumper sections are labeled MONITOR 1
and MONITOR 2. The factory default has
the jumpers set to the POST positions.
Reference Tone Frequency Configuration
Two configuration jumpers are used to
select the nominal frequency range of the
reference tone oscillator. A trim potentiom-
eter is then used to set the frequency to
the exact desired value. From the factory
the frequency of the reference tone is set
to be 400 Hz. This was accomplished dur-
ing the testing process in two steps. The
first step was to set the jumpers to the two
locations that are labeled 400 Hz. Then the
trim pot labeled TONE FREQ was adjusted
so that a 400 Hz signal was generated, as
measured between the COM and the TONE
test points.
To change the frequency to 1 kHz start by
moving the jumpers to the positions labeled
1 kHz. Then, using a frequency counter
or other measuring device, adjust the trim
pot labeled TONE FREQ so that a 1 kHz
signal is present on the test point labeled
TONE, when measured in reference to the
test point labeled COM. Finding the refer-
ence tone frequency configuration location
on the printed circuit board is not difficult.
When viewed from the front with the cover
off, it is located on the far right side of the
printed circuitry board, directly in front of
the mains power transformer. It is labeled
TONE FREQ.