The Science of Sound Recording

APPENDIX 1

Here are some examples of calculations involving decibels. Decibels are ratio measures that depend on standard reference values against which a variable amplitude is compared.

Example 1: We are connecting a device with a nominal output level of −10 dBV to a device with a specified input level of +4 dBu. When a signal is at the nominal amplitude, the device meter reads 0 VU. What will the input VU meter read when fed from the output?

Because the input expects an input of +4 dBu, the meter will read −7.8–4 dB, or −11.8 VU.

Example 2: How much peak-to-peak voltage is necessary to allow a +4 dBu RMS sinusoidal signal to pass through a circuit ...