Alan Blumlein (29 June 1903–7 June 1942) was an English electronics engineer, noted for his numerous inventions in the fields of telecommunications, sound recording, stereophonic sound, television, and radar. He earned 128 patents and was one of the most influential engineers and inventors of his generation.

Early life

Alan Dower Blumlein was born on 29 June 1903 in Hampstead, London. His father, Semmy Blumlein, was a German-born naturalized British subject. Semmy was the son of Joseph Blumlein, a German of Jewish descent, and Philippine Hellmann, a French woman of German descent. Alan’s mother, Jessie Dower, was Scottish, daughter of William Dower (born 1837), who went to South Africa for the London Missionary Society. Alan was christened as a Presbyterian; he later married in a Church of England parish church

What did Alan Blumlein invent?

In December of 1931, Blumlein patented an amazing new method of recording, which he termed “binaural sound.” The binaural sound was almost what we’d call “stereo” today. It used two microphones, recorded two separate recordings, and played back from two separate loudspeakers. Here are his achievements:

1. Telecommunications

In 1924, he started work in his first appointment at International Western Electric, a subsidiary of Western Electric Company, then International Standard Electric Corporation, and ultimately Standard Telephones and Cables (STC). It is there he made the measurement amplitude/frequency response of the human ears; then, he, based on this measurement, designed the first weighting networks.

In 1924 he published (with Professor Edward Mallett) the first of his only two IEE papers, on high-frequency resistance measurement. This won him the IEE’s Premium award for innovation. The following year he wrote (with Norman Kipping) a series of seven articles for Wireless World.

2. Sound recording

In 1929 Blumlein resigned from STC and joined the Columbia Graphophone Company, where he reported directly to general manager Isaac Shoenberg. His first project was to find a method of disc cutting that circumvented a Bell patent in the Western Electric moving-iron cutting head then used, and on which substantial royalties had to be paid. He invented the moving-coil disc-cutting head, which not only got around the patent but offered greatly improved sound quality. He led a small team that developed the concept into a practical cutter. Two other important team members were Herbert Holman and Henry “Ham” Clark. Their work resulted in patents.

3. Ultra-linear amplifier

In June 1937, Blumlein patented what has become known as the Ultra-Linear amplifier, US Patent 2,218,902, June 5th, 1937. What could have been quite a simple circuit was a breakthrough in design since it provided for a tap of the primary output transformer feeding the second grid; this improved linearity in an amplifier. Just like the tap set at the anode end of the primary winding, it was connected to the circuit as if it were just a triode; otherwise, it was located at the supply end, more or less as a pentode. Blumlein discovered that if the tap was placed at a distance of 15–20% from the supply end of the output transformer, the tube or valve would assemble the best desirable properties of the two designs, that is, a triode and a pentode.

4. Long-tailed pair

Blumlein may or may not have invented the long-tailed pair, but his name is on the first patent (1936). The long-tailed pair is a form of differential amplifier that has been popular since the days of the vacuum tube (valve). It is now more pervasive than ever, as it is particularly suitable for implementation in integrated circuit form, and almost every operational amplifier integrated circuit contains at least one.

5. Stereophonic sound

In 1931, Blumlein invented what he termed “binaural sound,” which is now more commonly known as stereophonic sound. In early 1931, he and his wife were at the cinema. The sound reproduction systems of the early talkies only had a single set of speakers—the actor might be on one side of the screen, but the voice could come from the other. Blumlein declared to his wife that he had discovered a means whereby the sound could follow the actor.

Contributions as an EMI Team Member

Television was developed by many individuals and companies throughout the 1920s and 1930s. Blumlein’s work, as a member of the EMI team, began in earnest in 1933 when his boss, Isaac Shoenberg, assigned him full-time to TV research. His concepts included:

• • Resonant flyback scanning (the use of a tuned circuit in the creation of a sawtooth deflection waveform). (British Patent No. 400976, an application filed April 1932.)

• • Application of constant-impedance network to power supplies to make the voltage regulation immune to changes in load frequency down to DC (421546, 16 June 1933).

• • Black-level clamping (422914, 11 July 1933 by Blumlein, Browne and Hardwick). This is an advanced version of the DC restoration device

• • The slot antenna. (515684, applied for 7 March 1939.)

Private life

Alan Blumlein was married and had two sons, Simon Blumlein and David Blumlein. Apart from his professional career, he was very fond of music. He tried playing the piano, but not for long. He enjoyed horse riding and at times accompanied his father-in-law on cub hunting.

What is the Blumlein stereo microphone technique?

The Blumlein Pair method uses two microphones with a bidirectional figure-of-eight pickup pattern, and they position them on top of each other—90 degrees off-axis from each other. Bringing microphone elements as close together as possible will help with phase coherence.

How Did Alan Blumlein Die?

Blumlein was killed in the crash of an H2S-equipped Handley Page Halifax test aircraft while making a test flight for the Telecommunications Research Establishment (TRE) on 7 June 1942. During the flight from RAF Defford, whilst at an altitude of 500 ft (150 meters) the Halifax developed an engine fire which rapidly grew out of control. The aircraft was seen to lose altitude, then rolled inverted and struck the ground. The crash occurred near the village of Welsh Bicknor in Herefordshire. Two of Blumlein’s colleagues, Cecil Oswald Browne and Frank Blythen, also died in the crash.