Peter L. Jensen

He began employment as an apprentice in the laboratory of Valdemar Poulsen, the inventor of magnetic recording[1] and the Poulsen System of Radio in 1903. Became assistant to Poulsen in 1905 and was sent to the United States to assist in introducing the Poulsen Radio Arc System in 1909. He was employed as engineer by the Federal Telegraph Company in California, which purchased the Poulsen patent, until November 1910.[2]

In 1911, he co-founded with Edwin S. Pridham (1881–1963) the Commercial Wireless and Development Co. in Napa, California, utilizing the financial backing of Richard O'Conner and the engineering assistance of master mechanic Carl Albertus.[3] Jensen and Pridham moved from Napa in 1916, and changed the company name in 1917 to the Magnavox Company. Jensen was employed as chief engineer until 1925.[4]

He built with Edwin S. Pridham the first moving coil loudspeaker in 1915.[5] Called the moving coil principle, the electro-dynamic principle from which the term dynamic speaker later evolved. In 1916 he built and patented the first contained and complete electric reproducing phonograph. Made the first public address system and used on Christmas Eve in 1915 in San Francisco at a gathering where 75,000 people were present and who heard distinctly all the speeches and announcements. The public address systems under the name of Magnavox were used all over the United States. It was used by U.S. President Woodrow Wilson in 1919. World-wide there were no other companies manufacturing public address systems until 1920. He designed the Magnavox dynamic loudspeaker for reception of radio broadcasting in 1919.

He also invented and patented, with Edwin S. Pridham, the first anti-noise self-neutralizing microphone in 1917 which allowed wireless communication between aircraft and the ground. This type later became known as the lip microphone, widely used in the First and Second World Wars.

Jensen resigned from Magnavox in 1925, and founded the Jensen Radio Manufacturing Company in 1927. He marketed speakers under the trade name "Jensen". He remained president of firm until 1940. He was a consultant to the Radio and Radar Division of the U.S. War Production Board in Washington, D.C., from 1942 to 1946. In 1945, he founded Jensen Industries Inc. for the manufacturing of phonograph needles—and, later in the manufacturing of the stainless steel sink.

Jensen was made an honorary Member of the Audio Engineering Society in 1955. he was honoured by the American Institute of Radio Engineers. He was elected an Extraordinary Member of the Danish Engineering Society, and knighted by the King of Denmark in the Order of the Dannebrog. [6]

• Magnavox Company

• History of Jensen Loudspeakers

• Peter L. Jensen and the Magnavox Loudspeaker
• In Memoriam

• Mette Stougård: Denmark's Forgotten Inventor. March 23, 2001

• Historical Monument in Napa, Ca.

• Jensen History