Film-Tech Forum ARCHIVE: Dolby SR Equipment Question

This is topic Dolby SR Equipment Question in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Michael Coate (Member # 757) on 10-02-2005, 07:54 AM:

Can someone explain the difference between the early Dolby SR processors, the 280T and SRA5?

Posted by Steve Guttag (Member # 268) on 10-02-2005, 08:51 AM:

First you need to define what you mean by " early Dolby SR processors."

The Cat. 280(T) was the noise reduction module used for existing Dolby equipment (like the 360 series of card frames) and was used in the SRA5 card frame (the only cinema based external SR processor for cinema). The Cat. 280T would also directly replace the Cat. 22 (Type-A card) in all existing cinema applications that used the Cat 22...like for the CP50, CP100 and CP200. However, one does not get the benifit of the SRA-5 to allow instant changes between A and SR type NR nor the prescribed 3dB boost on SR since SR films are recorded 3dB quieter to increase dynamic range due to the substantial noise reduction improvement.

Later cinema processors had SR included (no need for an external card frame or processing)...especially after Dolby Digital caught on since SR became the standard optical format.

Posted by Michael Coate (Member # 757) on 10-02-2005, 05:26 PM:

To clarify my poorly-written question, by "early Dolby SR" I meant during the 1987-1989 or so timeframe. Basically, before SR became a common, everyday optical/analog sound format.

I asked the question because I was recently looking over a list of Dolby SR locations from 1989 and for each venue on the list either 280T or SRA5 was identified as the "Dolby Equipment." My question was re differences between the two in terms of playback.

Posted by Steve Guttag (Member # 268) on 10-02-2005, 05:29 PM:

Thanks for the clarification...

That referrs to whether the theatre purchased the SRA-5 to add on to their existing CP50, CP55, CP100 or CP200. If they listed just Cat 280T...that meant that the theatre could play SR but only by swapping out the NR cards in their CP50, CP100, or CP200. The CP55 required the SRA-5 until the Cat 222SR/A that was developed MUCH later (after the CP65 came out).