Dolby Laboratories 737 - Manual (Page 12)

Model 737 Soundtrack Loudness Meter - Leq(m) Operation and Features
2-5
2.2.4 Power and Control
The 8-pin power and control connector uses the following wiring conventions for the
control and AC power signals:
Table 2-4 Power and control connector wiring convention
The trip output is a simple open collector buffer that passes current when the trip value
is exceeded. The voltage on the open trip contacts should not exceed 24 VDC and the
current passed when closed should not exceed 20 mA.
2.3 Connection and Calibration
The Model 737 may derive its input from a variety of signal sources including an audio
console, a cinema processor, the SDU4 Surround Decoder, the DA10/20 Digital Adapters,
and non-Dolby digital adapters. The Model 737 accurately measures both matrix-encoded
two-channel and decoded four- and six-channel sources. The following three important
points are independent of the signal source:
• Dolby Level should be used as the test signal input level. In the digital domain,
Dolby Level correlates to -20 dBFS (20 dB below Full-Scale digital).
• The calibration for each input must be performed with only that input connected.
When that input is calibrated, unplug it and plug in the next input to calibrate.
All inputs are connected after the calibration in preparation for the actual
measurement.
The calibration procedure is discussed in section 2.3.6. The following sections discuss
how to interface the Model 737 to the most commonly used signal sources.
2.3.1 Connecting to an Audio Console
Connect the Left, Center, Right, Left Surround, Right Surround, and Subwoofer outputs
from the audio console into the appropriate inputs on the Model 737. Use a 1 kHz tone at
Dolby Level as the test signal to each full-band input. Use a Dolby Level tone at approx-
imately 100 Hz for the Subwoofer input.
Pin Connection
1 Close to stop (+)
2 Close to stop (gnd)
3 Trip indicator (+)
4 Trip indicator (gnd)
5 Vref
6 24 VAC
7 Chassis ground
8 24 VAC
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