On Wed, 12 Dec 2012, Jay Ashworth wrote:
> Lots of "non-pro" gear interfaces with a 0 VU of, as you note, -10 dBV, which > is, as you imply, *not* 14 dB lower, because the baselines are different - > one is a power measurement which depends on the impedance; the other a > voiltage measurement which does not. My understanding is that dB is always a measure of power ratio. 10 dB down means 1/10 the power. I think what's confusing is the use of dB to measure differences in voltage level. It's not meaningful unless the impedance is the same. For example, 1 volt RMS across 100 ohms is the same level as 1 volt across 1,000 ohms, but the ratio between the two cases is 10 dB. But bridge a high-impedance mixer input across either, and the meters will read the same (or close to the same; the addition of the input impedance in parallel with each resistor will change the ratio slightly). Maybe it's time we actually start calling a volt a volt. Rob _______________________________________________ Rivendell-dev mailing list [email protected] http://lists.rivendellaudio.org/mailman/listinfo/rivendell-dev
