Dolby Surround Pro-Logic emerged in home theater systems in the early 1990's. It became the surround sound standard for Hi-Fi VHS, and is still the standard for today's analog TV broadcasts, since the Dolby Surround Pro-Logic signal can be encoded in a stereo analog signal. If you have an "older" Dolby Surround Pro-Logic receiver, you can still enjoy movies from DVD-Video, since all DVD-Video players down-mixes the Dolby Digital information to the Dolby Surround Pro-Logic format, and outputs the signal as a stereo audio pair.
What is Pro-Logic II? Pro Logic II from Dolby Laboratories gives you multichannel surround sound from any stereo source—CDs, tapes, videocassettes, TV broadcasts, AAC files, you name it. No matter if you're listening to Stravinsky, the Stones, or a Schwarzenegger movie, you'll get the realistic, involving sound you'd expect from a 5.1-channel system.
How Pro Logic II Works Pro Logic II is a dramatically improved, updated matrix surround system, based on the principles used to develop the original Dolby Pro Logic decoding back in the 1980s. The original Pro Logic features four channels—front left, center, and front right, plus a mono surround channel that's usually split between two rear speakers. The surround channel is also "band-limited," reducing the treble frequencies. Pro Logic II further enhances the sound with a full-range stereo surround output and a greatly improved steering logic, resulting in high channel separation and an exceptionally stable soundfield.
