Compander-type Noise Reduction Systems

Note: This information has been incorporated into this page which contains a more in-depth discussion.

I received an urgent phone call yesterday from a man who had digitized several reels of 2″ 24-track analog recordings that he wished to re-mix.

The tapes were originally recorded in about 1978-1979 and he said that he needed them to have Dolby C noise-reduction processing applied to the files.

I did a bit of research, as that did not sound correct from an historic point of view.

Here is an approximate chronology of the major noise-reduction systems and their dates of introduction:

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End of the 3.5″ floppy disk

CNET reported yesterday that Sony will be stopping sales of its 3.5-inch floppy disk media in March 2011 in Japan. Apple stopped supplying these as standard equipment in 1998 and Dell ceased that practice in 2003.

While this medium is not widely used for audio or video, there is, I suspect, still a large amount of ancillary data kept in this format. I will look through my collection and see if there is anything else I need to capture to my servers before my drives die.  I would not entrust anything important to this format.

We stopped using these about three or four years ago, with the last holdout being school work brought home. Now, even that is done on USB keys.

Cassette equalization redo

There has been much discussion on some web fora about the differences between different brands’ cassette equalization standards.

As I stated here in 2006, there is a 4 dB ambiguity at 16 kHz.

Many things conspire to make this 4 dB ambiguity essentially meaningless in a generally low-fi medium. The only reason I’m mentioning this now is that I’ve been bombarded with email from more than one participant in this discussion and apparently there may be some editorial judgment attached to what is posted.

Jay McKnight has graciously permitted my posting of his comments to me:

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IASA TC04 Guidelines on the Production and Preservation of Digital Audio Objects available online.

The International Association of Sound and Audiovisual Archives (IASA) has released their landmark Guidelines on the Production and Preservation of Digital Audio Objects as a free web (HTML) edition, available here.

I provided some information for the listing of tape equalizations, and I find the compiled table (here) most useful.

Thanks to Kevin Bradley and the IASA team for their work in making this available. If you want a PDF copy, join IASA and it’s available.

Another NAS contender…

revised 9:15 AM to add Synology

I was reading some additional NAS discussion on a photography list serve and was introduced to yet another NAS vendor that deserves consideration, QNAP. They appear to have wide distribution in North America (I found two online retailers that list them, CDW.CA and CanadaComputers.com. While the comparison was made to the Drobo products in the discussion I saw, these products appear to be similar in pricing and quality to Thecus and Netgear and offer some interesting options. Thecus units are more difficult to obtain, but Netgear units are also available at the two online dealers listed for QNAP. Yet another name just came up in the discussion, Synology. QNAP, Synology, and Thecus are all headquartered in Taiwan, while Netgear is headquartered in the U.S.

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