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Dolby A: Difference between revisions
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'''Dolby A''' is a noise reduction process created by Dolby Laboratories. It is used in many aspects of analog recording but for the purposes of Sprocket School we will be talking exclusively about its use with 35mm | '''Dolby A''' is a noise reduction process created by Dolby Laboratories. It is used in many aspects of analog recording but for the purposes of Sprocket School we will be talking exclusively about its use with 35mm stereo optical tracks and 70mm film prints with [[magnetic soundtracks]]. Dolby A can be used to refer to the noise reduction process itself, or to the stereo optical track found on 35mm prints. It is a 4 channel format- left, center, right and surround. | ||
'''It was in use from approximately 1975 to 1986, when it was largely replaced by [[Dolby SR]].''' | |||
It is important for projectionists to be able to distinguish between Dolby A and Dolby SR because the sound processor uses different circuitry to decode them. If you playback Dolby A as SR or vice versa, it will not sound correct. | |||
===Dolby A vs. [[Dolby SR]]=== | ===Dolby A vs. [[Dolby SR]]=== | ||
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* Some (but not all) films with Dolby A tracks will display the word "Dolby" - or "Dolby Stereo" rather than "Dolby SR" - with the Dolby logo in the end credits. But be careful, just because you see one of these in the credits of the film does not guarantee that it is A Type or SR. Some films were released as both mono and stereo prints, or a film may have been re-mastered and released as SR but was originally mono. Seeing the logo in the credits is just another clue to be used with alongside other sources of information. | * Some (but not all) films with Dolby A tracks will display the word "Dolby" - or "Dolby Stereo" rather than "Dolby SR" - with the Dolby logo in the end credits. But be careful, just because you see one of these in the credits of the film does not guarantee that it is A Type or SR. Some films were released as both mono and stereo prints, or a film may have been re-mastered and released as SR but was originally mono. Seeing the logo in the credits is just another clue to be used with alongside other sources of information. | ||
* Some (but not all) films with Dolby A tracks will display the words "Stereo" on the edges of the film [[leader]]. | * Some (but not all) films with Dolby A tracks will display the words "Stereo" on the edges of the film [[leader]]. | ||
* A Dolby A track played in Dolby SR will usually sound harsh or blown out | * A Dolby A track played in Dolby SR will usually sound harsh or blown out. A Dolby SR track played in Dolby A will sound acceptable, so if you really cannot figure it out Dolby A is the better choice. | ||
<gallery widths=250px heights=250px> | <gallery widths=250px heights=250px> | ||
File:Dolby stereo.jpg|Dolby Stereo logo. | File:Dolby stereo.jpg|Dolby Stereo logo. | ||