Which employer did Alan Blumlein work for in Dec 1923?
Alan Blumlein Alan Dower Blumlein ( 29 June 1903 – 7 June 1942 ) was an English electronics engineer , notable for his many inventions in telecommunications , sound recording , stereophonic sound , television and radar . He received 128 patents and was considered as one of the most significant engineers and inventors of his time . He died during World War II on 7 June 1942 , aged 38 , during the secret trial of an H2S airborne radar system then under development , when all on board the Halifax bomber in which he was flying were killed when it crashed at Welsh Bicknor in Herefordshire . Early life . Alan Dower Blumlein was born on 29 June 1903 in Hampstead , London . His father , Semmy Blumlein , was a German-born naturalised British subject . Semmy was the son of Joseph Blumlein , a German of Jewish descent , and Philippine Hellmann , a French woman of German descent . Alans 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 . Alan Blumleins future career seemed to have been determined by the age of seven , when he presented his father with an invoice for repairing the doorbell , signed Alan Blumlein , Electrical Engineer ( with paid scrawled in pencil ) . His sister claimed that he could not read proficiently until he was 12 . He replied no , but I knew a lot of quadratic equations ! After leaving Highgate School in 1921 , he studied at City and Guilds College ( part of Imperial College ) . He won a Governors scholarship and joined the second year of the course . He graduated with a First-Class Honours BSc two years later . In mid-1930 , Blumlein met Doreen Lane , a preparatory school teacher five years his junior . After two-and-a-half years of courtship the two were married in 1933 . Lane was warned by acquaintances before the wedding that , There was a joke amongst some of his friends , they used to call it Blumlein-itis or First Class Mind . It seems that he didnt want to know anyone who didnt have a first class mind . Recording engineer Joseph B . Kaye , known as J . B . Kaye , who was Blumleins closest friend and best man at the wedding , thought the couple were well matched . Career and inventions . Telecommunications . In 1924 Blumlein started his first job at International Western Electric , a division of the Western Electric Company . The company subsequently became International Standard Electric Corporation and then , later on , Standard Telephones and Cables ( STC ) . During his time there , he measured the amplitude/frequency response of human ears , and used the results to design 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 IEEs Premium award for innovation . The following year he wrote ( with Norman Kipping ) a series of seven articles for Wireless World . In 1925 and 1926 , Blumlein and John Percy Johns designed an improved form of loading coil which reduced loss and crosstalk in long-distance telephone lines . These were used until the end of the analogue telephony era . The same duo also invented an improved form of AC measurement bridge which became known as the Blumlein Bridge and subsequently the transformer ratio arm bridge . These two inventions were the basis for Blumleins first two patents . His inventions while working at STC resulted in another five patents , which were not awarded until after he left the company in 1929 . 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 which developed the concept into a practical cutter . The other principal team members were Herbert Holman and Henry Ham Clark . Their work resulted in several patents . Early in 1931 , the Columbia Graphophone Company and the Gramophone Company merged and became EMI . New joint research laboratories were set up at Hayes and Blumlein was officially transferred there on 1 November the same year . During the early 1930s Blumlein and Herbert Holman developed a series of moving-coil microphones , which were used in EMI recording studios and by the BBC at Alexandra Palace . Ultra-linear amplifier . In June 1937 , Blumlein patented what is now known as the Ultra-Linear amplifier ( US Patent 2,218,902 , dated 5 June 1937 ) . A deceptively simple design , the circuit provided a tap on the primary winding of the output transformer to provide feedback to the second grid , which improved the amplifiers linearity . With the tap placed at the anode end of the primary winding , the tube ( valve ) is effectively connected as a triode , and if the tap was at the supply end , as a pure pentode . Blumlein discovered that if the tap was placed at a distance 15–20% down from the supply end of the output transformer , the tube or valve would combine the positive features of both the triode and the pentode design . 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 . Stereophonic sound . In 1931 , Blumlein invented what he called binaural sound , now 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 found a way to make the sound follow the actor . Blumlein explained his ideas to Isaac Shoenberg in the late summer of 1931 . His earliest notes on the subject are dated 25 September 1931 , and his patent had the title Improvements in and relating to Sound-transmission , Sound-recording and Sound-reproducing Systems . The application was dated 14 December 1931 , and was accepted on 14 June 1933 as UK patent number 394,325 . The patent covered numerous ideas in stereo , some of which are used today . Some 70 claims include : - A shuffling circuit , which aimed to preserve the directional effect when sound from a spaced pair of microphones was reproduced via stereo loudspeakers instead of a pair of headphones - The use of a coincident pair of velocity microphones with their axes at right angles to each other , which is still known as a Blumlein Pair - Recording two channels in the single groove of a record using the two groove walls at right angles to each other and 45 degrees to the vertical - A stereo disc-cutting head - Using hybrid transformers to matrix between left and right signals and sum and difference signals Blumleins binaural experiments began in early 1933 , and the first stereo discs were cut later the same year . Much of the development work on this system for cinematic use was completed by 1935 . In Blumleins short test films ( most notably , Trains at Hayes Station , which lasts 5 minutes 11 seconds , and , The Walking & Talking Film ) , his original intent of having the sound follow the actor was fully realised . In 1934 , Blumlein recorded Mozarts Jupiter Symphony conducted by Sir Thomas Beecham at Abbey Road Studios in London using his vertical-lateral technique . Television . Television was developed by many individuals and companies throughout the 1920s and 1930s . Blumleins contributions , as a member of the EMI team , started in earnest in 1933 when his boss , Isaac Shoenberg , assigned him full-time to TV research . His ideas included : - Resonant flyback scanning ( the use of a tuned circuit in the creation of a sawtooth deflection waveform ) . ( British Patent No . 400976 , application filed April 1932. ) - Use of constant-impedance network in power supplies to obtain voltage regulation independent of load frequency , extending down to DC ( 421546 , filed 16 June 1933 ) . - Black-level clamping ( 422914 , filed 11 July 1933 by Blumlein , Browne and Hardwick ) . This is an improved form of DC restoration , compared to the simple DC restorer ( consisting of a capacitor , diode and resistor ) which had been patented by Peter Willans three months earlier . - The slot antenna . ( 515684 , filed 7 March 1939. ) Blumlein was also largely responsible for the development of the waveform structure used in the 405-line Marconi-EMI system – developed for the UKs BBC Television Service at Alexandra Palace , the worlds first scheduled high definition ( 240 lines or better ) television service – which was later adopted as the CCIR System A . H2S radar . Blumlein was so central to the development of the H2S airborne radar system ( to aid bomb targeting ) , that after his death in June 1942 , many believed that the project would fail . However it survived and was a factor in shortening the Second World War . Blumleins role in the project was a closely guarded secret at the time and consequently only a brief announcement of his death was made some two years later , to avoid providing solace to Hitler . His invention of the line type pulse modulator ( ref vol 5 of MIT Radiation Laboratory series ) was a major contribution to high-powered pulse radars , not just the H2Ss system , and continues to be used today . Death and investigation . 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 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 Blumleins colleagues , Cecil Oswald Browne and Frank Blythen , also died in the crash . The Halifax was carrying a highly-secret cavity magnetron as part of the H2S test system , and the immediate recovery of the device was essential . A team led by Bernard Lovell arrived at the crash scene the same night , and took the magnetron . Then reports of a crash in south Wales began to come in and the rest of that night was just a nightmare . I was driven by the C-in-C of the aerodrome [ Defford ] , a man called King , and winding through these lanes near Ross-on-Wye searching for this wreckage , and then the field with the burnt-out Halifax , and of course it was wartime , there was no time for emotions , our first duties were to search for the precious highly-secret equipment , and collect the bits-and-pieces of it . – Bernard Lovell . After the RAF investigative board completed its report on the Halifax crash on 1 July 1942 , it was distributed to a restricted list of approved recipients , but not publicly divulged . In the interests of wartime secrecy , the announcement of Blumleins death was not made for another three years . The investigative board , headed by AIB Chief Inspector Vernon Brown – who later also investigated the post-war Star Tiger and Star Ariel disappearances – and assisted by Rolls-Royce , who had made the Halifaxs Merlin engines , found that the crash was caused by engine fire , attributed to the unscrewing of a tappet nut on the starboard outer engine , which had been improperly tightened by an RAF engine fitter while inspecting the engine some three hours prior to the crash . During the flight the loosened nut caused increasingly excessive valve clearance eventually allowing collision of the valve head with the rising piston fracturing the valve stem , which then allowed the inlet valve to drop open , resulting in the ignition by the spark plug of the pressurised fuel/air mixture within the inlet manifold and , eventually , the pumping of the ignited fuel outboard of the rocker cover and along the outside of the engine , leading to an extensive fire in the engine nacelle . Due to the fire originating in the induction system , where the supercharged fuel/air mixture was at higher pressure than atmospheric , the heart of the fire was much hotter burning and intense than would be the case in a simple fuel fire . Constantly fuelled by the broken intake , the fire burned rapidly along the wing and fuselage , eventually causing the outboard section of the starboard wing to separate from the centre section at approximately 350 feet of altitude . With the loss of a substantial part of the starboard wing , all control over level flight was lost , and the plane rolled inverted and struck the ground at approximately 150 mph . The board found that the crew and passengers had not jumped immediately from the aircraft owing to several factors , including a loss of altitude while attempting to find an emergency field , the rapidly spreading fire , which blocked or impeded egress from the plane , and the fact that a sufficient number of parachutes were either not on board or were not being worn . Almost immediately following the crash , Prime Minister Churchill issued a directive requiring any test flights with civilians or scientific personnel to carry a sufficient number of parachutes for all individuals involved . After the RAF investigative board completed its report on the Halifax crash , it was ordered to be kept secret by Prime Minister Churchill , and the cause of the crash was not revealed publicly , even to the relatives of the deceased . As a result , numerous unfounded rumours of German sabotage as the cause of the crash would circulate for many years afterwards . Personal life . Alan Blumlein had two sons , Simon Blumlein and David Blumlein . Outside his work Blumlein was a lover of music and he attempted to learn to play the piano , but gave it up . He enjoyed horse riding and occasionally went cub hunting with his father-in-law . He was interested in many forms of engineering , including aviation , motor engineering and railway engineering . He obtained a pilots licence and flew Tiger Moth aircraft of the London Aerodrome Club at Stag Lane Aerodrome . On one occasion , he persuaded a bus driver to allow him to drive the vehicle from Penzance to Lands End . On another he spent several hours assisting the operator of a railway signal box in his duties at Paddington Station . Tributes . - Alan Blumlein Way is a road on the Tektronix campus in Beaverton , Oregon , in keeping with their policy of naming roads after those who made significant contributions to the knowledge and understanding in the field of electronics . - There continues to be a meeting room named the Blumlein Room in the Institution of Engineering and Technology ( IET ) headquarters at Savoy Place , following a major refurbishment in 2015 . - A Blue Plaque commemorating Blumlein was erected in 1977 by the Greater London Council at his former home in Ealing . - On 1 April 2015 an IEEE Milestone Plaque was posthumously presented for the Invention of Stereo to Alan Dower Blumlein . A ceremony was held at Abbey Road Sudios attended by many leading audio experts and recording engineers . The plaque is now located on the right hand side of the front door of Abbey Road Studios . - In 2017 , The Recording Academy posthumously awarded Alan Dower Blumlein with the 2017 Technical Grammy for the invention of Stereo and contributions of outstanding technical significance to the recording field .