Regarding the decibel terminology, I have to nitpick on one point: a dB is not the same as a dBu/dBv. A straight "dB" is always a relative scale unit, and can only be used to compare things together. A dBu (or dBv) is an actual, absolute unit, that happens to use the decibel scale. So "0 dBu" is equal to the power of 1 mW going through a 600 ohm resistance.
That is why gain in an amplifier (whether a speaker power amplifier or a tiny transistor) is counted in simple decibels (dB) since they compare the input to the output in the logarithmic scale (decibel scale). However, when you measure the output of a sound mixer, you may use the dBu unit as it refers to actual, physical quantities. On 17 August 2013 07:00, Cowboy <[email protected]> wrote: > On Friday 16 August 2013 09:15:13 pm al davis wrote: >> That is misleading. > > And that is precisely the point, and the reason this question > comes up so often ! > > To shorten the story greatly, db is ALWAYS a power ratio reference > by definition. Hence, zero was defined ( correctly so ) by Ma Bell > many many years ago, when I was just a little lad, as 1 mw in > 600 ohms, *THE* reference for all things bel. > > ( side note. Ma Bell deliberately defined the range to track the response > of the human ear ( or human eye ) so as to relate directly to human > perception of sound ( or light ) ratios ) > > Some years later, somewhere across the pond, 0 was incorrectly > defined as 1 volt. Since voltage is not power, this is and was > incorrect, and so has caused much confusion ever since. > > It *is* misleading. > > As long as anyone attempts to define voltage in terms that mean power, > it will always be misleading. ( and it's now so entrenched, we can expect > this will continue in perpetuity ) > > -- > Cowboy > > http://cowboy.cwf1.com > > Clothes make the man. Naked people have little or no influence on > society. > -- Mark Twain > > _______________________________________________ > Rivendell-dev mailing list > [email protected] > http://caspian.paravelsystems.com/mailman/listinfo/rivendell-dev -- Sébastien Leblanc _______________________________________________ Rivendell-dev mailing list [email protected] http://caspian.paravelsystems.com/mailman/listinfo/rivendell-dev
