Decibel Converter
dB to amplitude and power ratios, dBu/dBV/volts, bit-depth dynamic range and SPL over distance
How it works
Amplitude (voltage) ratios use 20 log10, power ratios use 10 log10: −6 dB halves the amplitude and quarters the power. dBu is referenced to 0.7746 V RMS and dBV to 1 V, so +4 dBu (pro line level) is 1.228 V and −10 dBV (consumer) is 0.316 V. Linear PCM has a theoretical dynamic range of 6.02 × bits + 1.76 dB, and a point source loses 6 dB of SPL each time the distance doubles.
Questions
Is −6 dB half as loud?
It's half the amplitude and a quarter of the power, but perceived loudness only drops by about a third — roughly 10 dB is needed to sound twice as loud or quiet.
What's the difference between dBu and dBV?
Different reference voltages: dBu uses 0.7746 V, dBV uses 1 V, so dBu = dBV + 2.22.
How much dynamic range does 24-bit audio have?
About 146 dB theoretical (6.02 × 24 + 1.76); 16-bit gives 98 dB. Real converters reach less.