Dolby Deterioration
Dolby SR or Spectral Recording was Dolby’s piece de resistance for analogue tape/film recording. It is still sold by Dolby as part of their Dolby Analog suite Review https://rapmag.com/a/39-90/mar90/152-test-drive-dolby-sr-model-363-sr-a?showall=1 Schematic from manual https://i.vgy.me/wWKZUz.png |
Speaking of Dolby.....I’ve always been mystified why Tea For The Tillerman is considered to have such good sound quality. I have had an original UK pressing of it since its’ release, and always found the drums to sound very muted---with no snap and stick-on-the head sound, and the cymbals almost absent. The acoustic guitar strings also lack sparkle and that "scratchiness" of the pick sliding across them. Michael Fremer discussed the difference between his original UK copy and the reissue on Mobile Fidelity, and panned the reissue, saying the highs has been boosted. Can you guess where this is heading? Turns out whomever mastered the original didn’t know it had been recorded with Dolby, so didn’t put the signal through the second half of the Dolby process, the part that restores the frequencies depressed during recording! The original is missing it's high frequencies, it's no wonder I don't hear the cymbals! That was not the case when Mobile Fidelity remastered the album. Their version was done using the correct Dolby processing, and their LP is what the recording actually sounds like. To his credit, it was Fremer himself who brought this to everyones’ attention. He may be full of himself, but he’s a big enough man to admit a mistake. |
Dolby SR!! I haven't heard that term in ages. As far as I knew it was a very short lived experiment in multi-band compression. It was (like Dolby A) a pro-only noise reduction format which came out after Dolby C. Like DBX. I vaguely seem to remember they attempted to use it for film and this did not last long. Not enough benefit, and getting the cards to match was difficult due to the high number of discrete parts. Then it vanished from my consciousness. |
Hey gang, so few different things are involved here. 1- The Dolby noise reduction professional (Dolby-A) was a monster card of parts and op amps. Dolby was not particularly careful with their designs when it came to noise and distortion. I know because I've taken some of those cards and others apart. 2 - Dolby Surround was awful for movies and music. It was impossible to get an enveloping, natural sound field, as it focused completely on effects and big screens with people seated in sub-optimal locations. On top of that, their processors were noisy and high distortion. I worked with prototype decoders that let you turn this down, and my god, you have never heard 2 channel movies like that. 3 - Dolby Digital eliminated the forced channel pumping of DS but the poor data rate forced high compression. Post DVD I believe (but I am not a composer/editor) that things have gotten a lot better for music and movie production. |
