tereo, the almost magical method of creating a wide spread of sound from just a pair of living room loudspeakers, was invented by a Brit – Alan Blumlein (pronounced Bloomline), who worked for UK company EMI. He was also a key figure in the invention of television and radar and movie stereo.
Blumlein’s life story is the stuff that Hollywood movies are made of. An absent-minded genius who died young doing secret war work, he was an electronics wizard who couldn’t read properly until he was 12 years old and would not read complete books until after his marriage. But for many years only a few engineers knew about him – largely from the 128 patents he filed for, one for every six weeks of his short working life.
Why has Blumlein not been a household name like Edison or Bell? Partly because he was way ahead of his time – developing stereo music discs and movie films when the public had no interest in – or cash for – anything more than one loudspeaker.
His work in the 1930s on television was shelved at the outbreak of war; and he died in a plane crash in 1942 while testing top secret World War II radar, which had spun off from his work on television. There is good reason to believe that the British government had encouraged the TV research because it tacitly stimulated development of a key component for radar – the cathode ray tube screen.
Much as happened at Bletchley Park, where the code-breakers worked in such secrecy that no outsider knew who lived or died there, the UK government postponed even a brief announcement of Blumlein’s death for three years. Churchill feared that the news would give solace to Hitler, who was ranting that British radar was the ruin of his U-boat campaign.
The lack of wider awareness of Blumlein’s achievements persisted long after the war, for a completely different reason. The first man to try and write a Blumlein biography, fell sick and died. His successor (who we will not dignify here with a name) collected all the available historical and family papers and talked a lot about being Blumlein’s official biographer, but never wrote anything.
Even the fiftieth anniversary of Blumlein’s death in June 1992 passed without a biography. It was only after the phoney biographer had been professionally discredited and died, that other researchers were able to finish the job. There are now two books on Blumlein. The first, by Robert Alexander, was published in late 1999 by Focal Press; then came another from Russell Burns, in January 2000.
Alan Blumlein joined the record company known as Columbia Graphophone in 1929. His boss, Sir Isaac Shoenberg, asked him to find a way round a string of patents owned by Bell and Western Electric on their method of recording sound electrically (rather than acoustically with a vibrating diaphragm that moved a stylus to cut a groove). Blumlein built a moving coil cutter which worked far better.
In 1931 Columbia Graphophone merged with the Gramophone Company, which owned the His Master’s Voice record label and the famous Nipper dog trademark. The result was a new company, Electrical and Musical Industries, later known just as EMI. Scientists working at EMI’s Lab in Hayes were given a very free hand to do Blue Sky research.
Blumlein was intrigued by the way our two ears hear a natural spread of sound from a limitless number of sources all round us arriving at different times or ‘phasing’. He wanted to mimic this spread effect with just two loudspeakers – not do as the engineers at Bell Labs in America were doing and use many loudspeakers.
Instead of trying to recreate the original sound field, Blumlein fooled the ear and brain. He built a simple circuit, called a shuffler, which converted subtle phase changes in sound to quite crude variations in volume level. Later he achieved the same effect with figure-of-eight (usually ribbon) microphones, which pick up sound only from the front and back; now known to recording engineers as a ‘Blumlein crossed pair’.
Each of our ears inevitably hears a mix of sound from each loudspeaker. When both loudspeakers are reproducing the same sound at the same volume level, our brain is fooled into thinking the sound is coming from halfway between the two loudspeakers; when the sound from one loudspeaker is slightly louder than the other, the apparent source shifts sideways.
By far the most important of Blumlein’s 128 patents was the one describing this stereo technique (number 394 325). The same patent tells how to record two channels of sound in the single groove of a gramophone record – or a single optical soundtrack down the side of a reel of cinema film. That patent has become a Bible for audio engineers. (See Blumlein’s Walking & Talking lab test film here).
By July 1933 Blumlein had started making test stereo recordings. In December he made a record which is now famous amongst sound engineers as the “walking and talking” stereo experiment. Engineers walk backwards and forwards across a room, in front of a stereo microphone.
In January 1934 Blumlein took his equipment to EMI’s recording studios at Abbey Road and cut stereo test discs of Ray Noble’s dance band and Sir Thomas Beecham conducting Mozart. But they were heard only by lab engineers.
It wasn’t until March 1958 that the record industry set a standard for stereo recording – and then the press referred to it as an American system. In a thundering editorial, in the April 1958 issue of The Gramophone, the technical editor Percy Wilson reminded the world that it was Blumlein who had invented and patented the system.
Engineers at Decca – EMI’s main rival – spent five years working on stereo in the early ’50s. Chief engineer Arthur Haddy told how it was only when Decca filed for a patent of its own, that the company discovered that everything of significance had already been invented and claimed by Blumlein in the ’30s.
EMI was able to keep the master patent in force until December 1952, thanks to special provisions that compensated inventors for the lost war years. But that was not long enough and neither Blumlein’s family nor EMI ever benefited financially from this seminal stereo patent.
Blumlein’s optical stereo sound film system was also forgotten for half a century after it was invented. In the Seventies Dolby Laboratories, the US company that became a household word with circuits that reduced the hiss of an analogue tape recorder, convinced the Hollywood film studios that they should start taking stereo sound seriously. The optical system developed by Dolby was very similar to the Blumlein system of the Thirties. And by then the world was ready for movie stereo.
It took Blumlein and his team just 18 months to design, develop and install a working 405-line all-electronic TV system which the BBC installed at Alexandra Palace in November 1936. It was immediately obvious that this was far superior to John Logie Baird’s mechanical spinning wheel system.
By May 1937 the EMI team had produced outside broadcast equipment which was capable of transmitting King George VI’s coronation, the first ever TV broadcast from outside a studio. The pictures were clear, despite an overcast day and very poor light. Blumlein had designed cables and amplifiers to carry the signals eight miles across London. The BBC canned the Baird system in February 1937 but the Blumlein/EMI system had to be shut down in September 1939 because of fears that German bombers might home in on Alexandra Palace.
Blumlein concentrated on his radar work. Halifax bombers were chosen for tests of airborne equipment. On June 7th 1942 Halifax number V9977 took off from Defford, crammed with experimental radar gear, with Blumlein and some other RMI engineers on board. The bomber was flying at around 2,500 feet when an engine failed, and caught fire. The fire extinguishers did not work well enough to stop the fire. All on board were killed.
On July 3rd 1942, Winston Churchill ordered that two squadrons of aircraft be fitted with Blumlein’s radar by October. The first bombing raid which used the equipment was on Hamburg, on the night of January 30th 1943. The returning pilots had nothing but praise for the equipment. One estimate is that Blumlein’s radar reduced U-boat losses in the North Atlantic from 50,000 tonnes a month in March 1943 to less than 4,000 tonnes just three months later.
The once-secret crash report blamed a new service procedure which Rolls Royce had introduced, ironically to make the Merlin engines safer. The tappets which controlled the engine valves had slightly reduced clearance.
Each engine had 48 lock nuts and there were four engines. So the ground crew fitters had to loosen a total of 192 lock nuts, adjust all the tappets and then tighten all the nuts again. On the fateful day one tappet nut in the starboard outer engine had not been fully tightened and came loose. The valve fractured, leading to catastrophic fire.
The EMI scientists did not have parachutes, and the crew had not felt able to jump leaving their passengers on board.
When, I wonder, will we see a Netflix series on Alan Dower Blumlein?