Model 737 Soundtrack Loudness Meter - Leq(m) Operation and Features
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2.3.4 Connecting to Non-Dolby Digital Adapters
With the digital adapter connected to the Dolby cinema processor, make a parallel con-
nection from the cinema processor to the audio inputs on the Model 737, and use the test
media from that manufacturer as the signal source to apply Dolby Level to each channel.
2.3.5 Connecting to the SDU4 Surround Decoder
The Model 737 can interface with the SDU4 either before or after decoding. To measure
the matrix-encoded signal, connect the signals intended for the SDU4’s Lt and Rt inputs
to the Lt and Rt inputs (channels 1 and 3) on the Model 737.
To measure the decoded signal, connect the four-channel L, C, R, S outputs from the
SDU4 to the Left, Center, Right, and Left Surround inputs on the Model 737.
2.3.6 Calibration Procedure
To obtain an accurate Leq(m) measurement, the input trimpots must be used to calibrate
the inputs to standard levels to account for the differing levels and formats of the various
signal sources. Use the table below to determine the calibration setting and follow the
steps below to calibrate the inputs.
Table 2-6 Calibration levels for Dolby, Dolby SR, and Dolby Digital soundtracks
1. Press the Cal button.
2. Send the appropriate test signal at Dolby Level to the first input only. Connect
only one input at a time when calibrating.
3. Adjust the input trimpot associated with that input until the + and - LEDs beside
the trims are of approximately equal brightness (null point) and the Leq(m) value
displayed is correct according to Table 2-6.
Dolby (Format 04) Dolby SR (Format 05) Dolby Digital
(Format 10)
Channel Level
(dB) Channel Level
(dB) Channel Level
(dB)
Lt (matrix encoded) 85 Lt (matrix encoded) 88 L 85
Rt (matrix encoded) 85 Rt (matrix encoded) 88 C 85
L (matrix decoded) 85 L (matrix decoded) 88 R 85
C (matrix decoded) 85 C (matrix decoded) 88 Ls 82
R (matrix decoded) 85 R (matrix decoded) 88 Rs 82
S (matrix decoded) 85 S (matrix decoded) 88 Sw 85
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