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VU Meters

November 10th Fact-of-the-Day

VU Meters were developed at Bell Laboratories to provide a standard way to measure voice-frequency signal levels. They were first publicly described by Chinn, Gannett, and Morris in a classic paper titled 'A new Standard Volume Indicator and Reference Level' that was published both in Bell Systems Technical Journal and in Proceedings of the IRE in 1940. It was originally envisioned that VU Meters always would be connected across a 600-Ohm source connected to a 600-Ohm load. However, in 1953 the IRE broadened its VU Meter specification to include use with other impedances, especially the 150-Ohm audio circuits that were becoming popular in the television broadcast industry at that time. ©2004 Martek International All rights reserved.

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