Talk:VU meter

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[edit] What is 0 VU really?

• The original definition of 1 milliwatt into 600 ohms agrees with 0 VU = 0 dBm.
• Federal Standard 1037C says that 0 VU = 0 dBm...
• IEEE 152-1991 says that 0 VU is 1 mW into "a resistance equal to the magnitude of the circuit impedance", which agrees with 0 dBm.
• "0 VU is +4 dbm and represents a voltage level of 1.228 volts." [1]
• "For a pure sine wave, 0 VU = 1 dBm," [2]
  • hints that the discrepancy is due to an "isolating resistor".
• "0 VU is defined to be a level of +4 dBu for an applied sine wave" [3]
• "0 VU often refers to either a +4 dBu or a +8 dBu signal." [4]
• 0 VU corresponds to:
  • +8 dBm in older broadcast and telephone equipment
  • +4 dBm in balanced recording equipment
  • -10 dBV in unbalanced recording equipment [5]
• "The VU (or Volume Unit) system is a hangover from early radio usage when 0 VU meant 100% of the legal modulation for the particular radio station." [6]
• "When the VU meter indicates "0" (typically a +4 dBm level), " [7] — Omegatron 01:13, 13 September 2006 (UTC)

0 VU = +4 dBm on sine wave. No doubt about it. That www.sizes.com article appears to misunderstand the source it cites. For a definitive answer, someone will need to go to the primary source for this: IEC 60268-17. Harumphy 09:37, 12 September 2006 (UTC)

No doubt for you, maybe... — Omegatron 21:53, 12 September 2006 (UTC)