Linked by Thom Holwerda on Sun 22nd Jan 2017 20:50 UTC
Multimedia, AV

While common magnetic tape uses very thin, plastic-coated iron oxide, "talking rubber" uses rubber impregnated with iron oxide. Iron oxide (a form of rust) is ferromagnetic, which means in the presence of a magnetic field, the electrons in the iron oxide magnetically line up and stay that way even after the magnetic field is turned off. This allows cassette tapes to create a “track” of magnetically aligned iron oxide when the electromagnet in a cassette recorder creates a magnetic field.

But with magnetic rubber, the iron oxide is actually mixed into the rubber material; the whole band becomes ferromagnetic, instead of just the coating. According to that Bell System Journal article, this “talking rubber” could be around 1/16 or 1/8 of an inch think, whereas magnetic tape was (even in the '50s) already much thinner at 1/1000 of an inch thick.

More obscure audio formats!

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More obscure audio formats?
by Moochman on Tue 24th Jan 2017 23:03 UTC
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After the last article about Elcaset, I went on YouTube to see what it was all about. And I found a treasure trove of videos about obscure audio formats on "Techmoan"'s channel:

One of the most interesting to me was the "Tefifon" - an endless loop plastic band in a cartridge, made in Germany in the 1950s, read with a needle like a record but with much better sound quality and run-time than the 78rpm phonographs of the day. Too bad it never caught on, it's really awesome:

Edited 2017-01-24 23:04 UTC

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