What is the difference between Dolby Pro-Logic and Dolby Digital?
Both are decoding systems for home theater sound. Dolby Digital is the successor to Dolby Pro-Logic. Pro-Logic is the more common of the two systems and is found on video tapes, laser disks, even DVDs. Pro-Logic is actually four channels of sound that is reproduced through five speakers. The four channels are: left, center, right and surround channels. The surround channel consists of two speakers, and in Pro-Logic the same sound comes from both speakers. Pro-Logic is typically an analog system. Dolby Digital is a discrete digital system offering six separate channels of sound with a dedicated subwoofer channel for deep bass. The six channels are: left, center, right, left surround, right surround and LFE (low frequency effect) for bass. DD is known as 5.1 channel sound. Dolby Digital has been declared the audio standard for DVD and HDTV. Dolby Digital offers greater dynamic range than Pro-Logic, better frequency response and improved separation between channels.
A. Dolby Pro Logic is a 4-channel surround system that provides left and right main speaker channels, a center channel to keep dialogue centered on the TV regardless of viewer location, and a mono surround channel (This mono signal is usually spilt between two surround speakers). Dolby Digital and DTS are a 5.1 to 7.1 channel surround system that provides left and right main speaker channels, a center channel, and discrete, full-range left and right surround channels. 7.1 systems have an additional two “presence channels” for the front, otherweise they are identical to the 5.1 system. The .1 in 5.1 is the Low Frequency Effects (LFE) channel. It sends additional bass information to the subwoofer-usually involving dramatic sound effects like explosions.
Both are decoding systems for home theater sound. Dolby Digital is the successor to Dolby Pro-Logic. Pro-Logic is the more common of the two systems and is found on video tapes, laser disks, even DVD. Pro-Logic is actually four channels of sound that is reproduced through five speakers. The four channels are: left, center, right and surround channels. The surround channel consists of two speakers, and in Pro-Logic the same sound comes from both speakers. Pro-Logic is typically an analog system. Dolby Digital is a discrete digital system offering six separate channels of sound with a dedicated subwoofer channel for deep bass. The six channels are: left, center, right, left surround, right surround and LFE (low frequency effect) for bass. DD is known as 5.1 channel sound. Dolby Digital has been declared the audio standard for DVD and HDTV. Dolby Digital offers greater dynamic range than Pro-Logic, better frequency response and improved separation between channels.
The Pro Logic, or Dolby Surround, sound you’ve heard on videotapes and laserdiscs in the past is what’s called a “matrixed” soundtrack. The left, center, right and surround tracks are combined into two channels in the studio, then decoded by your Pro Logic receiver out to the original four in your home theater. But Pro Logic doesn’t give you stereo surrounds like Dolby Digital, and sometimes the channels leak into each other.
Originally developed for movie theaters, Dolby Digital gives you that close-to-the-action feeling by providing 5 full-range channels, including separate left and right surround channels, plus a special low-frequency effects channel for enhanced impact from your subwoofer. Dolby Pro Logic provides only 4 channels of audio: 3 discrete channels for left, right and center speakers in front of you, plus a single surround channel that feeds 2 surround speakers that are placed to the sides or rear of your seat. Many manufacturers include both decoders in their new surround processors and receivers to provide maximum system compatibility.
Related Questions
- What is the difference between Dolby Surround, Dolby Pro Logic, Dolby Digital 5.1 and DTS 5.1? Is one better than the other?
- Can I hear 5.1-channel Dolby Digital programs over a regular stereo, Dolby Pro Logic, or Dolby Pro Logic II system?
- What is the difference between Dolby Pro-Logic and Dolby Digital?
