14
MODIIB STEREO PROCESSOR
thirds up from its counterclockwise position . Select
Music mode and turn on the music source that is feed-
ing the MODIIB. Turn the left and right music level
trimpots on the Output/Music Card to obtain a nor-
mal house level. These trimpots are factory set and
may not need adjustment. DO NOT TURN THESE UP
TOO HIGH as music-to-film crosstalk may occur.
Adjust the trimpots so that right and left music are set
to the same level. A way to accomplish this is to play a
stereo music selection with a good vocal track and
adjust either the left or right music trimpots for mini-
mum vocals in the surround channel.
The music circuit in the MODIIB has a simple matrix
which generates four channels of music from any 2-
channel stereo music source.
TIME DELAY:
Locate the 325 DIGITAL TIME DELAY Card. The bot-
tom of this card has a rotary switch. Each position
clockwise on the rotary switch equals 10 mSec (mil-
liseconds) of delay. Position 0 is the minimum delay
setting which equals 10 mSec of delay. Position 1 pro-
duces a total of 20 mSec of delay, position 2, 30 mSec,
etc. The maximum amount of delay possible is 160
mSec. Measure the distance in feet from the ideal seat
(which is usually 2/3 of the way back from the stage
speakers, centered side to side) to the stage speakers.
Now measure the distance from the ideal seat to the
nearest surround speaker. Subtract the two measure-
ments. Now add 20 to this number to get the delay (in
milliseconds) required in the auditorium. Set the
rotary switch to the nearest setting in milliseconds.
DIGITAL LEVEL SETTINGS:
Incoming signals feeding the DIGITAL INPUT termi-
nals MUST be trimmed externally
to match levels from the Stereo-
Optical signals. These adjust-
ments can be made at the output
of the external digital decoder or
interlock audio tape machine (see
manufacturer’s manual). Make
sure that all other B-chain calibra-
tion adjustments have been made
prior to adjusting the digital lev-
els (see special note in the PRE-
LIMINARY section of the B
CHAIN CALIBRATION).
This completes the B chain cali-
bration.
SECTION 6:
OPERATING
INSTRUCTIONS
The MODIIB system is one of the easiest systems to
operate. The Manager/Operator of the sound booth
should review the operation instructions to assure that
emergency functions are also understood, should they
ever be needed.
TURNING ON THE SYSTEM:
The sound engineer who installed the sound system
has provided a way to apply power to the system
through a master power switch or circuit breaker.
Also, several of the individual components in the
equipment rack have their own power switches.
Become familiar with all switches or breakers that con-
trol power to the sound equipment.
If the components are normally turned on individual-
ly, it is important that the processing components are
turned on first and the power amplifiers are turned on
last. This will allow time for the low level circuits to
stabilize so that the power amplifiers will not pass a
“turn-on thump” to the auditorium speakers. Repeat
in reverse order when turning off the system.
MUSIC SELECTION:
It is likely that the sound system will be turned on
before the arrival of the first audience of the day. The
MODIIB powers up in Music mode. If the music play-
er (CD player or tape machine) is running, music will
be heard in the auditorium and on the booth monitor.
Music may also be selected by pressing the front panel
MUSIC button.
PROGRAM SELECTION:
The automation should be set to select the proper for-
mats when needed. However, any format may be
overridden by simply pushing one of the Format but-
tons located on the front of the MODIIB.
FILM LEVEL FADER:
This control is located on the MODIIB Format Card
and is used to set the system level for any film format,
but not for music level. The system was calibrated
with the FILM LEVEL fader at the one o’clock posi-
tion, which is where most prints will play at a normal
level.
MUSIC LEVEL CONTROL:
The music level should have been preset by the
installer of the sound system. However, if any change
in music level is desired then the MUSIC LEVEL con-
trol can be turned to change the overall volume level.
POSITION
DELAY
0
10
1
20
2
30
3
40
4
50
5
60
6
70
7
80
8
90
9
100
A
110
B
120
C
130
D
140
E
150
F
160
mSec