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Filmmaking Dictionary: Number 0 / 0 dBV
Definition
0 dBV is an audio voltage level equal to 1 volt RMS. The dBV scale expresses other voltages relative to that one-volt reference. It appears in microphone-sensitivity figures, line-level specifications and audio measurement.
The capital V matters. dBV and dBu use different reference voltages, so the same number on both scales does not represent the same electrical signal level.
Useful Voltage Comparisons
| Level | RMS voltage |
|---|---|
| −40 dBV | 0.01 V, or 10 mV |
| −20 dBV | 0.1 V, or 100 mV |
| −10 dBV | About 0.316 V |
| 0 dBV | 1 V |
| +6 dBV | About 2 V |
The voltage relationship is dBV = 20 × log₁₀(V RMS ÷ 1 V). A 20 dB increase multiplies voltage by ten; an increase of about 6 dB doubles it. This electrical comparison should not be read as a direct rule for perceived loudness.
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dBV and Microphone Sensitivity
A microphone sensitivity specification may give an output in dBV for a stated sound pressure, often 1 pascal at 1 kHz. A sensitivity of −40 dBV/Pa corresponds to 10 mV/Pa. The sound-pressure reference is essential: the voltage tells you what the microphone produces under that test condition, not during every line of dialogue.
For a practical comparison, two microphones rated at −40 and −34 dBV/Pa differ by 6 dB in nominal output for the same stated acoustic input. The second produces roughly twice the voltage. That does not, by itself, tell you which microphone sounds better or has the lower self-noise.
Comparing dBV and dBu
0 dBV is approximately +2.2 dBu. To convert a dBV value to dBu, add approximately 2.2; to convert dBu to dBV, subtract approximately 2.2.
A common consumer nominal line level is −10 dBV, while a common professional nominal level is +4 dBu. Because those figures use different references, their difference is about 11.8 dB, not 14 dB. Actual devices may use other operating levels, so confirm their specifications.
Using the Numbers in a Production Setup
When connecting a receiver, playback device or mixer to a camera, compare the sending level with the input’s accepted range and selected mic/line mode. The use of dBV in a specification does not prove that a connector is balanced or unbalanced, and the connector shape does not establish its voltage limit.
There is also no universal conversion from dBV to dBFS. Digital level depends on the recorder or interface’s sensitivity, gain and alignment. A reference-tone check is more useful than assuming that the two devices’ zero marks match.
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Frequently Asked Questions
Does 0 dBV mean no audio?
No. It specifies a nonzero voltage: 1 V RMS.
Is a negative dBV specification a fault?
No. Many normal microphone and line signals are below the one-volt reference and therefore have negative dBV values.
Related Terms
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