Theta Digital Casablanca II, Руководство пользователя

Страница: 72 / 125

62
input jack.
Press the SETUP button 3 times to return to the INPUT SELECT page.
Setup Dolby Digital
In figure 41, button # 3 provides a two-page sub menu which allows the user to set up preferences pertaining to Dolby
Digital (AC-3), by INPUT SELECT button. The first page of this sub menu is shown in figure 43. These settings are
pertinent only when the MODE is Dolby Digital.
Figure 43 - Front Panel Display of the SETUP / INP Page 2 / DOLBY DIGITAL Page 1 Sub Menu
2 Channel Mode
Some Dolby Digital sources contain only two of the possible five main channels. This is usually noted on the material's
cover, in the form of " Dolby Digital 2.0" or “Dolby Surround” as opposed to "Dolby Digital 5.1".
Embedded in every two-channel Dolby Digital data stream is an indication of whether or not the material is Dolby
Surround encoded. There are three possibilities for this indication: Dolby Surround encoded; Not Dolby Surround
Encoded; or No Indication.
Regardless of the indication value, the user can instruct the Casablanca II to further process this decoded signal in
virtually any
MODE . For Dolby Surround encoded signals, use button # 1 ( 2CHEN – or 2 channel encoded) to indicate
which MODE should be used to further process the incoming signal. If the signal is non-encoded, use button # 2
( 2CHNEN – or 2 channel non-encoded) to indicate which MODE is desired for further processing. When a mode is
applied to a two channel Dolby Digital signal, first the signal must be Dolby Digital decoded, then this decoded signal is
further manipulated by the selected mode that is set in the
2CHEN or 2CHNEN parameters. When this is the case and
the additional selected mode is MATRIX , the MODE displayed in the LCD when in the INPUT SELECT MENU will say
“
DOLBY D MATX
”
If the indication is that the signal is not Dolby Surround encoded, or there is no indication, and the 2CHNEN MODE is
set to Dolby Digital, no additional surround processing will occur, thus producing a two-channel (stereo) output.
Compression
Dolby Digital contains provisions for reducing the dynamic range of a Dolby Digital source. This means reducing the
loudness of the loud passages and increasing the loudness of the quiet passages. Possible reasons for reducing the
dynamic range of a source include late night listening wherein loud moments may disturb others, and making tapes for
automotive / portable use wherein quiet passages may not be heard.
Casablanca II contains three parameters to control Dolby Digital compression. Button # 3 ( CMP ) simply turns the
compression ON or OFF . Button # 4 ( HCMP , or High Compression) controls the amount that loud passages will be
reduced. Button # 5 ( LCMP , or Low Compression) controls the amount that quiet passages will be increased. A larger
number indicates a greater amount of increase or decrease.
Note : Some Dolby Digital sources do not allow for compression, in which case altering these settings will not result in
an audible change.
Dialog Normalization
Press button # 6 to set the dialog normalization value. Dolby Digital contains the useful provision for making all Dolby
Digital sources have the same perceived loudness even though they may have been recorded or mixed at very different
levels. This is done by embedding in the data stream a value that the program material will need to be adjusted by to
conform to an average dialog level established by Dolby Laboratories. It should be noted that all channels are
adjusted, not just the center channel. Casablanca II contains two options for this setting:
ANLG (analog) or DIGI
(digital).
ANLG : Dialog normalization will be applied in the analog domain. This means that the level adjustment
number is read into Casablanca II’s main computer and the Casablanca II’s analog volume controls are
properly adjusted. This is the best-sounding and preferred setting.