10
MODIIC STEREO PROCESSOR
minal is the Stereo A / Stereo SR pin (see above). The
MODIIC will switch to either Stereo A or Stereo SR
depending on the location of a jumper (H3) located on
the Format Card.
The MODIIC is shipped to default to Stereo A in the
event of a digital decoder problem. In this default
mode, jumper H3 on the Format Card jumpers the
center pin to the “A” pin. For a default setting of
Stereo SR, you must move the H3 jumper to jump the
center pin to the “SR” pin. The factory default setting
of Stereo A should be adequate for most theatres.
However, if Stereo SR default is desired, then the
Format Card must be removed to access the H3
jumper. Make sure power is removed from the system
before removing any card or plugging one in.
OUTPUTS:
The MAIN OUTPUTS are labeled LEFT, CENTER,
RIGHT, LEFT SURROUND, RIGHT SURROUND,
SUB+ and SUB-. Shielded cable should be run
between these terminals and the next piece of equip-
ment in the sound system (equalizer, amplifier, etc.).
Convenient GROUND (GND) terminals are provided
near the outputs. A balanced subwoofer output is
available on the MODIIC to provides an easy means to
mono bridge the sub amplifier. The subbass output
may also be operated in an unbalanced configuration
by connecting to the SUB+ terminal and GROUND.
MUTING FUNCTION:
A convenient MUTE terminal on the back of the
MODIIC allows all output channels of the MODIIC to
be silenced whenever this terminal is grounded.
REMOTE FADER OPERATION:
The volume control of the MODIIC can be operated
remotely at another location, independent of the
STEREO MASTER FADER. This can be accomplished
by adding a remote, linear taper 10k ohm pot (to act as
a volume control) between the REM SEND and
GROUND terminals on the back of the MODIIC.
Connect the wiper of the remote pot to the REM
RETURN terminal.
The toggle switch on the right hand side of the Format
Card, labeled REMOTE/LOCAL, allows the operator
to select either local or remote volume control of the
MODIIC. This switch is easily accessible by removing
the four thumb screws that attach the front plate to the
MODIIC.
Note: Remote operation is for film formats only, and
will not affect the music level.
SECTION 5:
CALIBRATION
For more detailed information about setting up
SMART processors, see the
Theatre Sound for SMART
Systems guide. The Sound Systems should be turned
on for at least one hour before alignment. All doors
should be closed and the exhaust fan should be run-
ning if the MODIIC is placed in an equipment rack.
Note: Before plugging or unplugging cards in the
MODIIC during calibration, be certain power is
removed from the MODIIC. Otherwise, damage to
cards or the processor may result!
EQUIPMENT REQUIRED:
Sound Pressure level meter, real time analyzer (RTA)
with a calibrated microphone, dual trace oscilloscope,
multimeter, a tuning wand and appropriate test loops.
A CHAIN CALIBRATION
The A chain is usually considered to be the signal path
originating from the solar cell and continuing to the
processor’s master fader. This signal path includes the
preamp, noise reduction and matrix stages.
PRELIMINARY:
1. Clean soundhead optics, exciter lamp, optical lens
and solar cell before attempting a soundhead align-
ment.
2. Set exciter lamp voltage for at least 80% of rated
voltage.
BXM 9 volt 4 amp — 7.2 volts
BXN 10 volt 5 amp — 8 volts
Most foreign 6.3 volt 4 amp — 5 volts
3. Make sure film/cell spacing is approximately 1 mm
with the slit image striking the top one-third of solar
cell.
4. Connect oscilloscope and real time analyzer to the
Left and Right Preamp outputs on the rear terminals
of the MODIIC (marked LEFT PRE & RIGHT PRE).
5. Locate the Gain and Slit Loss controls on the
Preamp Card. Turn Gain controls fully clockwise.
Turn Slit Loss controls fully counterclockwise.
6. Turn the STEREO MASTER FADER all the way
down to avoid excessive noises in the auditorium for
the next steps.
