Quote:
Originally Posted by The Philpott
As i understand it audio tape machines from Germany which were only really good enough for the spoken word, were developed by the US after the war into something quite spectacular in terms of sound quality.
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The fundamental development which made magnetic recording work really well was the use of AC bias, which was (re)discovered by German Radio in 1941. This enabled a reduction in speed from 1m/s to 77cm/s at the same time as improving s/n ratio to over 50dB and extending frequency response above 10kHz. It was this machine that the Allies captured - subsequent development was more incremental than revolutionary, fuelled largely by improved tape formulae.
German Radio were even recording stacked stereo in 1944 - they had the heads to hand from experiments in recording two tracks at different levels to improve dynamic range on DC-biased machines, a line of research rendered pointless by AC bias, although 3M revived the idea in the 1960s - just before Dolby A emerged!
As regards durability, I have seldom had trouble with any BASF tape type. EMI are pretty good, too. Acetate tape goes brittle, or dissolves into a vinegary puddle. Both acetate and mylar bases are prone to physical distortion and require careful transfer if this happens.
Any record company should by now have digital safety copies of its masters. General good practice is to preserve the analogue originals against future improvements in playback technology.