Audio
Decibel (dB)
01 — Definition
A way of comparing two levels without dragging long strings of zeros around: the decibel expresses a ratio, never an absolute quantity. It is logarithmic — +6 dB doubles voltage, +20 dB multiplies it by ten, +3 dB doubles power. 0 dB does not mean silence, but no departure from the reference: dBu references 0.775 V, dBV references 1.0 V. Human hearing spans roughly 0 to 140 dB SPL.
02 — In the field
Pro line level lives at +4 dBu, consumer at −10 dBV. Mix the two without a DI and you get a level mismatch that sounds weak and thin.
04 — Sources
- Ballou, p. 54 — dBV référencé à 1 V, dBu à 0,775 V, dB SPL à 20 µPa ; +6 dB double la tension et quadruple la puissance