File:Vocarola loudspeaker.png
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editDescriptionVocarola loudspeaker.png |
English: Westinghouse Vocarola loudspeaker, an early radio loudspeaker sold between January 1922 and September 1923. Like most early speakers it was a horn loudspeaker, which used a coiled brass horn to amplify the sound produced by a small metal diaphragm vibrated by an electromagnet in the small cylindrical box (right, near bottom). It could either stand on a table or be attached to a wall. The cord plugged into the earphone jack of a radio. Two models were made: the Type I shown here, and the Type LV. It initially sold for $30, reduced to $18 the next year. The speaker was designed by Frank Conrad from an automobile horn. When radio broadcasting suddenly began in 1920, creating a demand for family listening, there were not many speakers on the market; most radios used earphones. Conrad tried attaching a reproducer from a Baldwin telephone earpiece to the coiled brass sound duct from an automobile horn. It worked well enough that he kept this design. The original mica diaphragm of the earpiece was replaced with a metal diaphragm to handle the higher power. (Information from Eric Wenaas (2007) Radiola: The Golden Age of RCA 1919-1929, Sonoran Publishing, p.142-143 ) |
Date | Prior to June 1922 |
Source | Downloaded March 14, 2013 from Radio Broadcast magazine, Doubleday, Page and Co., Vol. 1, No. 2, June 1922, p. 184 on Google Books |
Author | Unknown authorUnknown author |
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editPublic domainPublic domainfalsefalse |
This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.
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This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.
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current | 16:21, 18 April 2013 | 1,050 × 1,758 (342 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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Horizontal resolution | 28.35 dpc |
Vertical resolution | 28.35 dpc |
File change date and time | 06:50, 15 March 2013 |