What is dBV?

dBV or decibel Volt is the decibel unit for measuring voltage; relative to 1 V. RMS (Root-Mean-Square) voltage is often used to represent the strength of a signal. 1 V(RMS) corresponds to 0 dBV. So any positive value of dBV represents a voltage greater than 1V, and any negative dBV value represents a voltage below 1 V. 

The following equation is used to convert Voltage (RMS) into equivalent dBV unit.

Here, the root-mean-square (RMS) value of voltage is used rather than peak-to-peak (p-p) because the RMS value tells us the “average” of a signal that has both negative and positive amplitudes along its waveform.

Example: If Voltage = 10 V(RMS). Voltage (in dBV) = 20 log10 (10V / 1V) = 20 dBV

 The following table shows the dBV equivalent for some common Voltage values. 

The dBV unit is generally used in the audio industry for specifications of input and output levels of consumer audio equipment and measuring the strength of the audio signals in the audio applications. The main benefit of using dBV representation in audio engineering is that this unit better correlates with human hearing, and we can express both very large and very small values in a short range of number.

The dBV unit can also be converted back to its voltage (RMS) using the following equation: