Dolby Laboratories 737 - Manual (Page 9)

Model 737 Soundtrack Loudness Meter - Leq(m) Operation and Features
2-2
2.1.1 6/4 – 2 Channel Switch
Located to the left of the input trimpots (see Figure 2-2), this switch may be used in
future versions to introduce a fixed offset in the measurement of two-channel encoded
material. Presently (version 1), the offset is set to zero so the switch has no effect on
the measurement.
2.1.2 Input Trimpots
To derive accurate and repeatable Leq(m) measurements, the input trimpots are used to
calibrate the Model 737 to standard input levels. The input trimpots are screwdriver-
adjustable and allow sensitivity adjustments from -12 to +4 dBu for Dolby Level to suit
a wide variety of console setup levels and cinema processor types. See Section 2.3 -
Connection and Calibration for a complete discussion of how to connect and calibrate
the Model 737 to different signal sources.
2.1.3 Trip Set
Trip Set is a 16-position switch that sets a value from 78 Leq(m) at position 0 to 92 Leq(m)
at position E in 1 unit increments. When Stop is pressed to end the measurement, if the
Trip Set level has been exceeded, the Trip LED lights and a signal is sent to Trip Out.
The Trip LED does not light during the measurement to allow transient Leq(m) values
to exceed the Trip Set value without triggering Trip Out.
Note: The Trip circuit can be disabled by setting the switch to position F.
The current Trip level can be checked by holding down the Cal button then pressing
and holding the Stop button. This test always sends a signal to Trip Out to check the
circuit operation. Push the Run button to cancel the trip indication. In position F, the
display is blank.
2.1.4 Pushbuttons
• Cal – Push to enter calibration mode to set audio input levels using the trim-
pots. In calibration mode, Mon Out sends a mono mix of the channels instead
of the output of the filter. Push Start to return to measurement mode.
• Start – Push to begin a measurement.
• Stop – Push to stop a measurement and display the final level of the measurement.
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