Microphone Sensitivity Calculator
Convert between microphone sensitivity specs in dBV, mV/Pa, and dBu. Enter values for instant results with step-by-step formulas.
Formula
dBV = 20 x log10(mV/1000) | dBu = dBV + 2.21
dBV is decibels referenced to 1 volt. mV/Pa is millivolts per pascal of sound pressure. dBu is decibels referenced to 0.775 volts. The 2.21 dB offset between dBV and dBu comes from 20 x log10(1/0.775).
Worked Examples
Example 1: Converting Condenser Mic Specs
Problem: A condenser microphone is rated at -34 dBV sensitivity. Convert to mV/Pa and dBu, and determine how much preamp gain is needed for line level.
Solution: dBV to mV/Pa: mV/Pa = 10^(-34/20) x 1000 = 19.95 mV/Pa\ndBV to dBu: -34 + 2.21 = -31.79 dBu\nLine level target = -12 dBV\nGain needed = -12 - (-34) = 22 dB of preamp gain\nOutput at 94 dB SPL = 19.95 mV\nOutput with 22 dB gain = 19.95 x 10^(22/20) = 251 mV
Result: 19.95 mV/Pa | -31.79 dBu | 22 dB preamp gain needed for line level
Example 2: Dynamic Mic Preamp Requirements
Problem: An SM57-type dynamic microphone has 1.6 mV/Pa sensitivity. What are the dBV and dBu values, and how much gain is needed?
Solution: mV/Pa to dBV: 20 x log10(1.6/1000) = -55.92 dBV\ndBV to dBu: -55.92 + 2.21 = -53.71 dBu\nLine level target = -12 dBV\nGain needed = -12 - (-55.92) = 43.92 dB\nOutput at 94 dB SPL = 1.6 mV\nOutput with 44 dB gain = 1.6 x 10^(44/20) = 253 mV
Result: -55.92 dBV | -53.71 dBu | 44 dB preamp gain needed for line level
Frequently Asked Questions
What is microphone sensitivity and why does it matter?
Microphone sensitivity is a specification that indicates how much electrical output voltage a microphone produces for a given sound pressure level input, typically measured at 1 Pascal of pressure which corresponds to 94 dB SPL. Higher sensitivity means the microphone produces a stronger signal, requiring less amplification from a preamp. This matters because every stage of amplification adds noise to the signal chain. A more sensitive microphone paired with moderate preamp gain will typically produce a cleaner recording than a less sensitive microphone requiring high gain. Sensitivity is expressed in different units depending on the manufacturer and standard: dBV (decibels relative to 1 volt), mV/Pa (millivolts per pascal), and dBu (decibels relative to 0.775 volts).
What is the difference between dBV, mV/Pa, and dBu sensitivity ratings?
These three units all express the same physical property but use different reference standards. dBV references 1 volt, so a sensitivity of -40 dBV means the output is 40 dB below 1 volt at 1 Pa input. mV/Pa directly states the millivolt output for 1 Pascal of sound pressure, making it the most intuitive unit. dBu references 0.775 volts, which is the voltage that produces 1 milliwatt across a 600-ohm load, a legacy from telephone engineering. The conversion between dBV and dBu is straightforward: dBu equals dBV plus 2.21 dB. To convert from mV/Pa to dBV, use the formula dBV equals 20 times log10 of the millivolt value divided by 1000. Understanding these conversions is essential when comparing microphones from different manufacturers who may use different specification standards.
What is a typical sensitivity range for different microphone types?
Condenser microphones are generally the most sensitive, typically ranging from -25 to -35 dBV (56 to 18 mV/Pa). Their active electronics and lighter diaphragms allow them to produce higher output levels. Large-diaphragm condensers tend to be more sensitive than small-diaphragm models. Dynamic microphones, which use a moving coil and magnet, typically range from -50 to -60 dBV (3.2 to 1 mV/Pa). The Shure SM57 and SM58, for example, have sensitivities around -56 dBV (1.6 mV/Pa). Ribbon microphones are the least sensitive, often measuring -55 to -65 dBV (1.8 to 0.56 mV/Pa), which is why they require high-quality preamps with substantial clean gain. Active ribbon microphones with built-in amplifiers can achieve sensitivities comparable to condensers.
How does microphone sensitivity affect preamp gain requirements?
The relationship between microphone sensitivity and preamp gain is inversely proportional. A microphone with low sensitivity requires more preamp gain to reach a usable recording level, while a highly sensitive microphone needs less gain. The target is typically to reach line level, approximately -12 to -20 dBV, at your recording interface input. For a condenser microphone at -30 dBV, you might need 15 to 20 dB of preamp gain. For a dynamic microphone at -55 dBV, you would need 35 to 45 dB of gain. The critical consideration is that preamp noise increases with gain. Budget preamps with a noise floor of -125 dBV can introduce audible hiss when operated at 50 dB or more of gain, which is why pairing low-sensitivity microphones with high-quality, low-noise preamps is essential for professional results.
What is equivalent noise level and how does sensitivity affect it?
Equivalent noise level, also called self-noise or equivalent input noise, is the sound pressure level that would produce an output equal to the microphone inherent electrical noise. It is expressed in dB-A (A-weighted decibels SPL). Lower values indicate quieter microphones. A microphone with 14 dB-A self-noise is considered very quiet, suitable for recording ambient sounds and soft instruments. Self-noise of 20 dB-A is acceptable for most studio applications, while anything above 25 dB-A may be noticeable in quiet recording situations. Sensitivity affects this indirectly: a more sensitive microphone converts more acoustic energy to electrical signal, improving the signal-to-noise ratio before amplification. This is why condenser microphones, with their higher sensitivity, typically have better self-noise specifications than dynamic microphones.
How do I match microphone sensitivity to my audio interface?
Matching microphone sensitivity to your audio interface requires understanding the interface preamp specifications: maximum gain, noise floor, and input impedance. First, determine how much gain your preamp can provide, typically 40 to 65 dB for prosumer interfaces. Then check if that gain is sufficient to bring your microphone output to a healthy recording level. For a -55 dBV dynamic microphone recording a soft source at 60 dB SPL, the mic output would be approximately -89 dBV, requiring about 65 dB of gain to reach -24 dBV recording level. If your preamp maxes out at 55 dB, the signal will be too quiet. Solutions include using a cloudlifter or fethead inline preamp that adds 20 to 25 dB of clean gain before the interface, or choosing a more sensitive microphone for that application.