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Topic: Difference Betwen Cat.No. 22 A-Type and Cat.No.222 Dolby A/SR Noise Reduction
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John Pytlak
Film God
Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000
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posted 06-16-2004 11:39 AM
This may help:
http://www.dolby.com/ken/
quote:
Welcome to the Ken's Corner table of contents!
Here you will find every installment of "An Introduction to Noise Reduction" published to date.
An Introduction to Noise Reduction
Table of Contents
Part I: Noise Modulation
Part II: The Ideal Noise Reduction System
Part III: Dynamics of Noise Reduction Systems
Part IV: Compression and Expansion Curves
Part V: More on Compression and Expansion Curves
Part VI: Realizing the Bilinear Compression Characteristic
Part VII: Putting It Together
Part VIII: The Sliding Band
Part IX: Action Substitution
http://www.dolby.com/company/is.ot.0011.TechOverview.04.html
quote:
Dolby Stereo, introduced in 1975, was Dolby Laboratories' first major contribution to film sound: the multichannel analog optical soundtrack for 35 mm prints. Dolby prints have two soundtracks matrix-encoded with four sound channels: left, center, and right for speakers behind the screen, and a fourth surround channel for ambient sound and special effects heard over speakers to the sides and rear of the cinema. Other improvements include the use of Dolby A-type noise reduction to lower the hissing and popping associated with optical soundtracks, and loudspeaker equalization to adjust the cinema sound system to a standard response curve.
Dolby SR, the advanced recording process introduced in 1986, was first applied to Dolby stereo optical soundtracks (in lieu of A-type NR) the following year. Analog SR soundtracks feature a significantly improved dynamic range, and are found today on almost all 35 mm release prints. The SR track makes it possible for the prints to play in any cinema, even if it is not equipped for digital playback, and also provides a backup in case of problems with the digital track.
http://www.dolby.com/news/sum90/sum90.html#s5
quote:
Taking Full Advantage of Dolby Stereo SR
by Ioan Allen, Vice President
When Dolby SR is applied to 35 mm stereo optical soundtracks, background noise is reduced to a level below the ambient noise of the best theatres, useful frequency range is extended, channel separation is improved, and overall dynamic range is significantly widened. In fact, this level of quality cannot be fully utilized in many theatres.
When a theatre adds the decoding equipment, some of Dolby SR's benefits automatically accrue. But only theatres with the best playback equipment and acoustics are able to realize all the benefits of Dolby SR, and so bring to life a new, higher standard of motion picture presentation.
To help more theatres reach this goal, Dolby Laboratories has developed a set of minimum playback specifications necessary to realizing the full potential of Dolby SR. Theatre owners and equipment installers are encouraged to study "Technical Guidelines for Dolby Stereo Theatres Updating for the Playback of Dolby SR Films" (S89/8320). We would also be pleased to send a copy to anyone with a particular interest in the state of the art in film sound reproduction.
Other Dolby publications:
Questions and Answers About Dolby SR For 35 mm Release Prints
Dolby Stereo Films list (all titles to date, including SR)
Dolby Stereo Equipped Theatres (U.S. and Canada, including SR)
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Stephen Furley
Film God
Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002
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posted 06-16-2004 01:31 PM
Marin, the Cat 22 and the Cat 222 are both A type cards. They are not compatible with each other. The Cat 22 has a single channel of noise reduction, and is used in older processors such as the CP-50 and the CP-200. The Cat 222 has two channels of noise reduction, and is used in later processors, such as the CP-55 and CP-65. The Cat 280 is a single channel SR card, which can replace a Cat 22, but for use in cinema processors you need a slightly modified version of the card, a Cat 280T, it's a very simple modification which you can do yourself to a standard Cat 280, but any card which has been modiifiiied should be clearly labeled as such. A pair of Cat 280 cards can also be used in an external unit, known as an SRA5
There is a version of the Cat 222, the 222 SR/A, which does both A type and SR processing, but the SR processing is saiid to not be as good as that on the other SR cards. This card can be used in place of a standard Cat 222 in CP-55 and CP-65 processors, but older units need to be modified before it can be used. It is also used in the CP-45. The Cat 222SR/A was introduced as a cheaper way to get SR processing. The other, better, way to do it with a CP-65 is to use two Cat 350 cards for SR, along with a single CAT 222.
The Cat 300 is similar to the Cat 350, but provides 'A' type processing, in addiition to SR. It is used in the recording industry, but its only use in cinema processors was in a special version of the CP-65 where, combined with a Cat 222, it enabled playback of four channels of 'A' type magnetic sound.
I'm afraid it gets a bit complicated. What model of processor do you have, this will determine which options are available to you.
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