Dolby 365 Two-Channel Processor with two Cat 22 (A) and two Cat 280 (SR) Cards


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The Dolby 365 is a 2U, two-channel Dolby rack processor compatible with Dolby A, SR and other noise reduction cards. Dolby A was used on millions of 16- and 24-track 2″ multitracks and 2-track masters. It’s a 4-band compander which boosts levels on recording and compensates on playback to reduce noise

Dolby SR was the successor to Dolby A and offers around 10 dB more noise reduction. Tapes encoded with SR require an SR card for decoding

A Cat 22 (or other other A card) is needed to encode or decode Dolby A-encoded tapes. A Cat 280 (or other SR card) is needed to encode or decode Dolby SR-encoded tapes

This 365 comes with a pair of Cat 22 (A) cards and a pair of Cat 280 (SR) cards. These cards are compatible with all early Dolby racks including the 365

Cards & Racks

The first generation of Dolby processors includes the 360, 361 and 365 rack. They are compatible with a number of Noise Reduction cards

The separation of interface (rack) and encode / decode NR cards makes the system very flexible. You can change noise reduction type just by swopping cards. If you want to modify a Cat 22 it’s simple to buy a spare card, modify it and plug it into the rack

Cat 22 is an encode / decode card for Dolby A

Cat 280 is an encode / decode card for Dolby SR

The most common Dolby interface is the single-channel Model 360/361. This is a deep, heavy unit (5.5 Kg) with a non-standard mains connector. The 365 is the same size as two 361s (2U) but houses two NR cards and uses a standard IEC mains connector. Unlike the 361, the 365 doesn’t weigh the same as a small car. This makes it easier to live with

Second-generation interfaces like the Dolby 363 used a NR card with a different connector. Racks & cards from the two generations are not compatible but encoded tapes are

The Dolby Trick

For the Dolby Trick you need a Dolby A card such as the Cat 22

A by-product of Dolby A encoding is that it can impart a soft, breathy quality to voices. The encoding process lifts low-level, high-frequency content and, by not decoding the signal, the processing can be used as an effect. This led to a few engineers using Dolby encoding for vocal processing when mixing, a procedure nick-named “The Dolby Trick”

The effect is level-dependent, with lower input levels resulting in the higher frequency bands being enhanced more than low frequencies. This means the effect can be increased by reducing the input level

Many experiments have been done to alter Dolby encoding and make it more usable as an effect. The simplest approach is to encode the signal and vary the input level to control the depth of the effect. This requires no modifications. Some have modified the Cat 22 cards with front-panel pots or switches. See the links below for details

Standard, but heavy, 19" 1U device suitable for all 19" racks. 220-240 Volt & standard IEC mains socket. Mains cable supplied on request
Instruction manual (Dolby 361) Dolby Trick - GroupDIY Dolby Trick - Gearslutz
Excellent used condition