Nope, there are many cases were the relationships between voltages are expressed in dB (the consumer line level -10 dBV being just one) dB ratios for voltages are Log20 though.
Bill On Dec 12, 2012, at 12:19, Rob Landry <41001...@interpring.com> wrote: > > > 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 > Rivendell-dev@lists.rivendellaudio.org > http://lists.rivendellaudio.org/mailman/listinfo/rivendell-dev _______________________________________________ Rivendell-dev mailing list Rivendell-dev@lists.rivendellaudio.org http://lists.rivendellaudio.org/mailman/listinfo/rivendell-dev
