Pioneer VSX-45TX manual Techno Tidbits & Problem-solving, 105, Dolby Digital, Dolby Pro Logic

Techno Tidbits & Problem-solving

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.

5.1 channel 4 channel analog

Dolby

Digital

Dolby Digital for movie

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.

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.

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

	Pro Logic	Pro Logic II
Effective sound source	Dolby Surround encoded sources	All two channel stereo sources
Surround Sound	Mono	Stereo
Frequency Range	Surround within 7kHz	All Channels/Full Range

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.

EXPERT

memo • For receivers and components other than the VSX-45TX Dolby Pro Logic II may not have the	105
above mentioned functions.