Talk:Magnetophon

Allies knowledge of wartime Magnetophon

This sentence has been flagged as dubious: 'Allied intelligence experts knew that the Germans had some new form of recording system but they did not know the details'

The BBC were aware of the Magnetophon before the war: Edward Pawley was able to examine one.It was still in its early stages - for one thing the tape frequently broke - but it was considered that it might eventually become useful.

During the war the Germans discovered that high-frequency bias would improve the quality considerably, and the brittle cellulose acetate tape was replaced by PVC (poly vinyl chloride). The use the Germans were making of the Magnetophon was known from an article entitled 'Radio changed over to magnetic steel tape' wqhich appeared in 'Das Reich' at the end of 1944. However it was not until the invasion and the capture of some machines that the reasons for the improvement in recorded quality which had become apparent from Hitler's broadcast speeches was known.

Information from 'BBC Engineering 1922-1972' by Edward Pawley, page 387.

Is it felt we need that much clarification in the article? I've added a brief parenthetical clarification with a reference. RFWilmut (talk) 16:12, 8 September 2013 (UTC)

Don't think the article needs further clarification. The BBC had been experimenting with steel wire and later flat steel tape themselves since the early 1930's and would have had some knowledge of German pre-war developments through trade shows and general contacts among the engineering community in their respective countries. Yes the Allies were confounded by how the Germans were able to achieve such good results with programme material known to have been recorded. But some accounts exaggerate their degree of ignorance about German technical developments. They were well aware of magnetic recording and probably suspected the Germans were using some improved type of magnetic recording process but just hadn't figured out how they achieved such improvements. BTW Some Wikipedia articles #1 #2 give different dates for the date for discovery of HF bias while this one says 1941.94.0.215.193 (talk) 13:04, 31 October 2015 (UTC)

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Question

The article fails to mention one thing: what tape speed(s) did those early Magnetophons use??? Lee M (talk) 00:04, 8 September 2018 (UTC)

Huge! It was so fast, and such a mechanical problem, that they tended to run at variable speeds. You'd trade off sound quality for reliability. The RAF wire recorders used for ELINT flights in the 1950s had a real problem with this, recording long surveillance runs where much of the flight was unimportant, then there was a brief interval of great interest – but there was probably only a few seconds of radar worth listening to, and the broadcast was only recorded once.

Actual speeds were five or six times later tape speeds. As a round number, 100 cm/s (that's a whole metre!), was one. Andy Dingley (talk)

Well, actually 100 cm/s is only about 2.6 times faster than 38 cm/s (15 ips), which is the industry standard, and only 30% faster than 76 cm/s (30 ips), sometimes used for higher quality, so... Lee M (talk) 21:58, 18 December 2018 (UTC)

The Magnetophon did not run at 100 cm/sec (though an earlier developmental machine did which proved unreliable - this was the machine that was demonstrated to Thomas Beecham). AEG subsequently specified a 10 cm diameter capstan directly powered by an induction motor. The resultant speed was 76.8 cm/sec. AEG considered the actual speed unimportant as long as all machines ran at the same speed.

The Americans on capturing some Magnetophons realised that 76.8 cm/sec was coincidentally very close to 30 in/sec (76.2 cm/sec) which became the subsequent standard speed of the day (that is: until submultiples started to be used - 15, 7+1⁄2, 3+3⁄4, 1+7⁄8 etc.). The 0.7% difference in speed went un-noticed if original magnetophon tapes were played on later machines (and vice versa) though there was the small matter of a difference in tape widths (6.5 mm for the magnetophon and 1⁄4 inch (6.35 mm) for all subsequent machines). 2A00:23C8:9883:A001:4546:D950:CE05:2C58 (talk) 15:21, 23 July 2024 (UTC)

Since posting the above, I have been researching what tolerance on tape speed was specified for analogue tape recorders. Nearly all service manuals for both reel-to-reel and cassette machines specify plus or minus 1.5%, so the difference between the magnetophon machines and the later 30 inch/sec speed was less than half of that which was later specified. Simpler battery cassette machines specified 2%, but the only way of altering the speed was to change the motor pulley as they had a built in governor which was not adjustable. 2A00:23C8:9883:A001:C14C:A073:C062:54D4 (talk) 14:27, 24 July 2024 (UTC)