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Dolby Pro Logic II
Dolby Pro Logic II is an improved version of Dolby Pro Logic technology with extended matrix decoding
technology that can create 5.1 channel sound from two channel sources. Dolby Pro Logic II creates basic 5
channel sound by using the innovative "steering logic" circuit. Therefore when listening to typical two-channel
sources like CD, the listener can enjoy a richer spatial effect. When using software encoded with Dolby
Surround, this decoding system affords the listener an improved surround experience with greater sound detail.
Chart Comparing Dolby Pro Logic and Dolby Pro Logic II
This unit has a three Dolby Pro Logic II functions. The first is "MOVIE Mode" (suitable for film soundtracks);
"MUSIC Mode" (suitable for music); "Pro Logic Mode" (this mode is less sensitive to the quality of the source
material, so may be useful when Movie Mode or Music Mode do not give good results). One can select one of
them depending on your soundtrack of choice.
Techno Tidbits & Problem-solving
5.1 channel
4 channel analog
Dolby
Digital
Dolby Digital for movie
memo
Surround Sound Mono Stereo
Pro Logic Pro Logic II
Effective sound source Dolby Surround encoded sources All two channel stereo sources
Frequency Range Surround within 7kHz All Channels/Full Range
Soundtracks using linear PCM audio generate too much
data for multichannel use. Dolby Digital technology was
developed in response to the need for efficient
multichannel digital sound. It uses masking technology and
Adaptive Transform Coding, resulting in no audible loss of
sound quality. In the present age of digital sound Dolby
Digital is a standard audio format for DVD and has been
adopted by HDTV broadcasts throughout the USA.
Dolby
Dolby Digital
Dolby Digital is a discrete digital surround format used for multichannel surround sound. It was developed after
the Dolby Surround System and Dolby Pro Logic Surround System. Dolby Digital is a high quality digital sound
format that is used by many theatrical film releases.
Other features include:
1) Downmixing on playback for compatibility with mono,
stereo, Dolby Pro Logic and 5.1 channel audio.
2) A wide range of bitrates and channels.
3) Decoding dynamic range information and adjusting the
dialog level in the soundtrack (called Dialog Normalization,
see below for more information).
The advantages of the Dolby Digital system of encoding
allow it to maintain its high quality sound while at the same
time being very flexible, with the ability to handle many
different types of soundtracks.
Dialog Normalization
When a Dolby Digital soundtrack is played back the Dialog Normalization function of the receiver activates auto-
matically. Dialog Normalization is a Dolby Digital function that establishes the average dialog level for the program
source being played. If the receiver's level does not match the average dialog level, first you see "DIAL NORM" and
"OFFSET +4 dB" (as an example) appear in the receiver's display. In this example, the number +4 dB is the differ-
ence between the receiver's gain structure and the Dolby Digital average dialog level. To match the average dialog
level, subtract or add the OFFSET level. For example, if the OFFSET level is +4 dB, the amplifier's output is 4 dB
over the average recorded level.
• For receivers and components other than the VSX-45TX Dolby Pro Logic II may not have the
above mentioned functions.