Dolby Laboratories CP650 Installation Manual download pdf (Page 163)

Dolby

Model CP650 Installation Manual Format Definitions

D-3

Format 10

Dolby Digital Film (Cat. No. 773 required)

Short name: Dolby Digital

Audio Description: The input is from the Dolby Digital reader, which provides the

signal to the Dolby Digital decoder and creates six discrete channels (L, C, R, Ls, Rs,

SW). The optical soundtrack is processed as in Format 05 at all times, to enable rapid

reversions to analog film sound when needed.

On a reversion event, the following actions take place:

1. The subwoofer level is set back to 0 dB, relative to the center channel passband.

2. The subwoofer lowpass filter is set to 50 or 100 Hz.

3. The downward expander is turned on.

4. The sound crossfades from the digital audio to the optical to minimize the

audibility of the reversion.

On an “unreversion” event, the following actions take place:

1. The subwoofer level is set back to +10 dB, relative to the optical subwoofer level.

2. The subwoofer lowpass filter is set to 180 Hz.

3. The downward expander is turned off.

4. The sound crossfades from the optical audio to the digital, to minimize the

audibility of the unreversion.

Format 11

External 6-Channel

Audio Description: This external audio format has six discrete channels (L, C, R, Ls,

Rs, SW), is input via the six-channel analog input D-connector, and can be used when

an external digital processor is utilized. The subwoofer channel level is +10 dB

referenced to the optical, with no downward expander.

Format 13

Dolby Digital Surround EX Film (Cat. Nos. 773 and 790 required)

Short name: Surround EX

Audio Description: This format is very similar to Format 10. Digital audio is

processed normally. The Cat. No. 790 (or earlier Cat. No. 794) applies the

Surround EX matrix decoder to the unequalized Ls and Rs channels, which yields the

channels Ls, Bs (which are copied into the Bsl and Bsr channels), and Rs. The out-of-

phase information is discarded. The audio for the screen channels and subwoofer is

output via the CP650’s main audio outputs, and the audio for the four surround

channels is output via the “Option card I/O” D-connector. Note that reversions occur

exactly the same as in Format 10.

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Dolby Laboratories CP650 Installation Manual Page 163