The Second World War is widely remembered as a technological war in which both sides raced to out-manoeuvre their opponent using cutting-edge science. And while many of those innovations would subsequently have a lasting global impact such as the invention of Radar, Jet Engines and the Atomic Bomb, not every idea would prove to be as successful or even memorable in the longer term.
A short while ago I was pleased to stumble across a (possibly now unique) instruction manual which had been hand put together in 1944 to help personnel service a new prototype ‘High Fidelity’ tape player which the Americans were working on in secret.
Although magnetic tape had first been invented by the German Fritz Pfleumer back in 1927 and then championed by the manufacturing giant AEG during the 1930s, it is fair to say its quality remained lower than that of a standard gramophone recording. Indeed, their plastic-coated tape would not become the backbone of the audio industry really until the early 1950s and would be largely overlooked until the very end of the war when the Allies began to discover that the Germans had quietly refined their tape and players quite substantially during the intervening years. Even immediately after the war it was still felt that steel wire recorders would give better quality results overall and for a few short years wire recorders did dominated the market. But the ease of production and versatility of plastic tape would ultimately give it the edge over its metal counterparts.
Magnetic Tape Recorder 1,2,3
By 1943 the Allies were firmly entrenched in an intelligence led war, and while detecting and listening to enemy activity was getting ever more accurate, they still possessed few ways to clearly record it for later analysis. Reconnaissance planes and ships for instance could not use more traditional record-cutting machines due to the natural turbulence, and instead had to go with wire recorders which gave a somewhat lack-lustre result.
To tackle this problem directly, the US government-backed Airborne Instruments Laboratory (AIL) based at Columbia University took it upon themselves to devise their own ‘high-fidelity’ tape recorder, and it is this machine which is fully explained in the confidential manual I found. Dated August 1944 with the schematics dated June 44, the manual suggests only a single prototype tape recorder was ever made, and that this was merely ‘copy number 4’ of the associated instruction manual. Clearly this was a project kept closely under-wraps.
The magnetic tape recorder AIL came up with was not as versatile as the German built Magnetofon but was smaller and probably easier to reload. It measured 21 x 10 x 8 inches and weighed 13kg and all visual signs suggest it was designed to be fitted into an instrument panel or rack rather than carried around by hand. It used a solid alloy loop of thin flat tape similar in size to the German tape which was 116 feet long and pre-wound into an attached cassette drum. While I won’t go into the finer details of this machine, the alloy tape would have made it far stronger than its competition. This would have been necessary because it spooled around the machine at much faster speeds and being solid increased the potential quality of the recording. The only thing is being metal it had to come with its own ‘welder’ to rejoin the tape together if needed. Of course as this was a maintenance manual I found rather than an evaluation report, it sadly didn’t go into how good the tonal quality really was, but since AIL labelled it ‘Hi-Fi’ we can only suppose it was indeed pretty good. The recorder itself was designed to work alongside a super hetrodyne Model S-36 Hallicrafter radio receiver or similar, which was widely used by the allies for covert listening purposes. It was also versatile enough to allow it to be connected to an oscilloscope to transfer the recording visually if desired, I presume to work alongside radar and sonar systems.
By this point of the description the AIL tape player probably sounds like it was a pretty equal match to the mighty German Magnetofon, yet there was one important and fundamental catch. With a fixed loop of tape running at far higher speeds and an automatic demagnetiser built into the system, this prototype player could only ever capture 17 seconds of audio before it would begin over-writing itself again. Granted the recording would be high quality for its day, and I guess you could leave it on like a CCTV system constantly over-writing itself during the quiet spells, but when something really interesting was heard it only gave 17 second intervals to capture that audio. Indeed 17 seconds is about the time it takes to read out loud my previous two sentences only. While an efficient operator may have been able to swap tape cartridges over relatively quickly, to do this four time a minute was completely unrealistic.
By the Autumn of 1944 as the Allies finally began to head towards Berlin, a few of the newer German magnetic tape recorders (branded Tonschreiber) were captured and passed over to military intelligence. Their capture, together with the inherent pitfalls of the Airborne Instrument Laboratory machine probably brought this Hi-Fi tape project to a close. It appears also to have been very quickly forgotten about even within AIL, as in 1946 the project was not even recorded in their summary of wartime activities which was written up by group.
Against such a background I very much doubt that this AIL prototype machine survives to this day and as I can find nothing at all relevant on the internet, one must presume that my instruction manual is probably the last remaining evidence for the project’s existence. It is in that respect a unique document and a fascinating window into another of our early attempts to create a really high-quality recording device.