File:Horn speaker with girl.jpg
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Summary[edit]
| Description |
English: Large antique horn loudspeaker from 1927 electrical engineering magazine, with girl sitting in mouth to show the scale. Before cone-type loudspeakers took over around 1930, radios and phonographs used horn loudspeakers, because they were more efficient; they could produce ~10 dB (10 times) more sound power from the low power vacuum tubes then in use. However to reproduce bass frequencies adequately the horn had to have a large mouth and long sound path, at least 6 feet long. The walls are made of a heavy composition material, often cloth impregnated with cement, so they do not vibrate and resonate when the sound passes through them. This was a high fidelity speaker probably used either in a theater or a large expensive cabinet type radio. The speaker tube is 10 feet long, wrapped around the horn body, and the unit weighed 185 lb. |
| Date | |
| Source | Retrieved March 6, 2014 from Paul G. Andres, "The Modern Exponential Horn Type Loud Speaker" in Radio Engineering magazine, Radio Engineering Magazine, Inc., New York, Vol. 7, No. 10, October 1927, p. 967, fig. 3 archived on American Radio History website |
| Author | Paul G. Andres |
| Permission (Reusing this file) |
This 1927 issue of Radio Engineering magazine would have the copyright renewed in 1955. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1954, 1955 and 1956 show no renewal entries for Radio Engineering. Therefore the copyright was not renewed and it is in the public domain. |
Licensing[edit]
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This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs. Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 11:34, 11 March 2023 | | 468 × 494 (37 KB) | Tucvbif (talk | contribs) | cleaned up |
| 05:16, 13 July 2014 |  | 467 × 493 (28 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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