INSTALLATION & OPERATION
13
Required Equipment
·
sound pressure level meter
·
real time analyzer (RTA) with a calibrated microphone
·
dual trace oscilloscope
·
multimeter
·
a tuning wand
·
S.M.P.T.E. Buzz Track Loop
·
C.A.T. #97 Stereo Cell Alignment Film
·
C.A.T. #69 Test Film
Before Calibrating
Turn on sound systems for 1/2 hour.
Turn off the EX feature.
Close the auditorium doors.
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
Clean soundhead optics, exciter lamp, optical lens and
solar cell before attempting a soundhead alignment.
Set exciter lamp voltage for at least 80% of rated voltage.
BMX 9 volt 4 amp – 7.2 volts
BXN 10 volt 5 amp – 8 volts
Most foreign 6.3 volt 4 amp – 5 volts
Make sure film/cell spacing is approximately 1 mm with
the slit image striking the top one-third of the solar cell.
Open the MOD VI front panel and connect Oscilloscope
and real time analyzer to the TP7 (left preamp) and TP8
(right preamp) test points.
TP7 and TP8 are located on the bottom side of the front
center of the MOD 7 main board between the J1 and J2
connectors. TPG (GROUND) is located to the left of J1, also
on the bottom side.
Turn Gain controls fully clockwise.
Turn Slit Loss controls fully counterclockwise.
The Preamp Gain controls are R1 and L1 for projector 1,
and R2 and L2 for projector 2. The Slit Loss controls are
LHF1 and RHF1 for projector 1, and LHF2 and RHF2 for
projector 2. Both sets of trimpots are located on the left
hand side of the front of the main circuit board.
SYSTEM SETUP
Turn the master FADER all the way down to avoid
excessive noises in the auditorium for the next steps.
Soundhead Alignment
1
Play a S.M.P.T.E. Buzz Track loop.
2
Adjust the lateral film guide assembly, laser lens
assembly or exciter lamp assembly while monitoring the
preamp signals with the oscilloscope.
3
Adjust for minimum signal on the left and right chan-
nels.
Refer to specific instructions in the projector soundhead
manual. Minor variations in alignment procedure depend
on the individual mechanical design of the soundhead.
4.
Play C.A.T. # 97 Stereo Cell Alignment Film.
5.
Move laser lens or solar cell laterally and vertically
until you have achieved minimum crosstalk between
channels (see figure 6).
6.
Repeat steps 1-5 until no further improvement can be
obtained.
7.
Play Pink Noise side of C.A.T. #69 Test Film.
8.
Switch oscilloscope to X/Y Mode.
9.
Adjust sound head optical lens azimuth for narrowest
diagonal trace (see figure 7).
Figure 6. Low crosstalk between channels
