Re: arsclist Dolby and unintended consequences

["joe@xxxxxxxxxxx" <sergei01@xxxxxxxxxxxxx>]

1 comment Richard - As I recall, the dolby B standard for consumer cassettes
was slightly different from that of FM, if so this might be better listed as
2 standards

Joe Salerno
Video Works! Is it working for you?
PO Box 273405 - Houston TX 77277-3405
http://joe.salerno.com
joe@xxxxxxxxxxx
----- Original Message -----
From: "Richard L. Hess" <arclists@xxxxxxxxxxxxxxx>
To: "Association of Moving Image Archivists" <AMIA-L@xxxxxxxxxxx>;
<ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Tuesday, June 25, 2002 5:48 PM
Subject: arsclist Dolby and unintended consequences


> Hi,
>
> A couple of weeks ago, Jim Wheeler pointed me to an article by Dave
Moulton
> in TV Technology
> http://www.tvtechnology.com/features/Inside-Audio/f-dm-badaudio.shtml that
> addressed some "bad audio" problems related to Dolby noise reduction.
>
> The article specifically addressed Dolby C encoding on Beta video decks.
> According to the article, the early Beta decks had a switch to turn the
> Dolby on and off (much like most cassette recorders). Further, the article
> states that with the advent of BetaSP, that switch was eliminated and
> permanently wired "on."
>
> I'm sending this email out just in case someone doesn't realize that the
> Dolby and dbx noise reduction processes are double-ended and a
> fully-functional unit is required to properly reproduce the encoded tape.
>
> There are no plug-ins to DAW software (to the best of my knowledge) that
> will decode any of these noise reduction systems. You're stuck either with
> the hardware built into the player or with the outboard decoders.
>
> These processes will sometimes magnify errors if the tapes or playback
> machines are not in great condition. In addition, it is possible to have
> defective decoders (don't ask me how I know). In all cases, trust your
> ears. If you think you're hearing a noise reduction problem, try and get
to
> the bottom of it sooner rather than later.
>
> Dolby C is built into Sony's Beta decks as well as Panasonic's MII decks.
> Dolby A was optional on 1-inch Type C videotape. I suspect that a few quad
> tapes might have been recorded with Dolby A, and that Dolby A might have
> been used on other formats as well in limited quantities.
>
> As to audio-only recordings, perhaps this would be a good time to just
> mention the different flavors of noise reduction companding that have
> existed. I may even have missed one or two:
>
>    DOLBY
>      A-the first studio standard (interrupted tone)
>      SR-the second studio standard (noise reference)
>      B-the first consumer standard (widely used on cassettes)
>           also used on FM broadcasts
>      C-the second consumer standard
>          also used on some semi-pro multi-tracks and video formats
>      S-the third consumer standard (used on some cassettes
>          and some semi-pro multi-tracks
>
>    DBX
>      I - the pro standard
>      II - the consumer standard also used on discs, FM broadcasts,
>           and in the stereo TV standard for the difference and pro
channels.
>
>    BURWEN
>      Although noted for his single-ended noise reduction products
>      they also produced for a time a 3:1 linear compander.
>
>    TELEFUNKEN
>       C4D ? this was yet another, incompatible, compander system with
>       some penetration into Europe.
>
> FYI, I have multiple copies of processors for Dolby A, SR, and B, and dbx
> I, and II. I don't have any for Dolby C (other than on cassette) or Dolby
S
> nor the Burwen nor Telefunken systems.
>
> Remember, the metadata on the tape box about the noise processing MIGHT BE
> WRONG. (I've had that happen more than once).
>
> Good luck.
>
> Any questions, please email or post to the list.
>
> Cheers,
>
> Richard
>
> -
> For subscription instructions, see the ARSC home page
> http://www.arsc-audio.org/arsclist.html
> Copyright of individual posting is owned by the author of the posting and
> permission to re-transmit or publish a post must be secured
> from the author of the post.
>


-
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