Dolby HX AES 1979 Demonstration Cassette (HQ Noise Reduction Funk Tape Capture)

Описание: This is the official Dolby demonstration tape for the original Dolby HX "Headroom eXtension" system for standard cassette tapes. This tape is from October 1979 and was either presented at, produced for, or distributed around the 64th AES Convention that took place November 2nd - 5th, 1979.

As the tape begins to explain, Dolby HX is a patented feedback system which varies the amplitude of the bias when recording onto cassette tape. This increases the saturation level (or headroom) of the tape, particularly for the higher frequencies, allowing for better high frequency response and lower distortion without the need for any special tapes or decoders on the playback system. This system also varies the equalization of the high frequencies.
This particular tape was produced as one of the first public demonstrations during the announcement of the system. In fact, the patent request for HX was submitted only a couple months prior!

This is a demonstration tape for the ORIGINAL Dolby HX system system. The Dolby HX Pro system, which is almost ubiquitously found on cassette decks produced after 1987 or so, is a modification of this earlier system. It's hard to find reliable sources but according to the internet, HX Pro was developed by B&O engineers as they were implementing Dolby HX into their cassette decks. They discovered a modified feedback system and made an audible difference without requiring an equalization circuit. This simpler and higher performing system was then patented by B&O & Dolby to then be commercially implemented as HX Pro. As a result, it appears that the original HX system featured on this tape was only implemented on a few unusual cassette decks (such as the Tascam 122 [1st Gen.] & Harmon-Kardon HK2x00XM series) before being quickly replaced with HX Pro.

Please enjoy this rare demonstration into a prototype technology that forever changed cassette deck performance!

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This was played back using a restored Aiwa AD-F990 cassette deck with Dolby B noise reduction enabled.

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