(The Relationship Between Microphone Sensitivity and Audio Interface Gain)
Introduction
The microphone preamp gain switch allows users to adjust amplification to match different microphone types.
Dynamic microphones usually offer multiple gain levels to accommodate varying sensitivities — lower-sensitivity microphones require higher interface gain.
Before making adjustments, confirm the microphone’s sensitivity rating.
In principle, the sum of the microphone sensitivity and interface gain should be close to 0 dB.
For example:
If the microphone sensitivity is –45 dB and the interface gain is +40 dB, the combined result is –5 dB, meaning the microphone will work properly.
If the total value is too far below 0, the output will be too quiet;
if it exceeds 0 dB, the signal will distort or clip.
Dynamic microphones generally have sensitivities between –55 dB and –65 dB.
High-end dynamic mics tend to have lower sensitivities, so it’s recommended to confirm the exact sensitivity with the manufacturer or seller.
1. Microphone Sensitivity
Definition:
Microphone sensitivity refers to the output voltage a microphone produces when exposed to a standard sound pressure (usually 94 dB SPL = 1 Pa).
Common units:
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mV/Pa (millivolts per pascal)
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dBV/Pa (decibels relative to 1V per pascal)
Characteristics:
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High sensitivity: Produces higher output voltage under the same sound pressure (e.g., –35 dBV/Pa).
-
Low sensitivity: Produces lower output voltage under the same conditions (e.g., –55 dBV/Pa).
Examples:
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Condenser microphones → high sensitivity (larger output signal)
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Dynamic microphones → low sensitivity (smaller output signal)
2. Audio Interface Gain
Definition:
Gain refers to the amplification level provided by the audio interface or preamp to boost the weak microphone signal.
Unit:
Measured in dB (decibels) — e.g., +40 dB, +60 dB.
Purpose:
Microphones output very weak electrical signals (in millivolts).
Gain amplifies these signals up to line level (in volts), suitable for computers or recording devices to process.
The gain knob controls how much amplification is applied.
3. Simple Analogy
🎤 Microphone Sensitivity
→ Think of it as how loud the microphone’s own voice is.
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A high-sensitivity mic has a loud voice — it can pick up sounds clearly even when you speak softly.
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A low-sensitivity mic has a quiet voice — you need to speak louder or get closer for it to capture sound properly.
🎚️ Audio Interface Gain
→ Think of it as the volume knob of a loudspeaker.
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Higher gain → amplifies the sound more.
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Lower gain → amplifies less.
🔗 Relationship Between the Two
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Low-sensitivity microphone (quiet voice) → needs higher gain to sound clear.
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High-sensitivity microphone (loud voice) → needs lower gain to avoid distortion or clipping
📌 Example
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PD300 / PD200X (Dynamic microphones, low sensitivity)
→ Like someone with a small voice who needs a powerful loudspeaker to be heard. -
PM320 (Condenser microphone, high sensitivity)
→ Like someone with a naturally loud voice who needs only a small speaker to fill the room.
👉 In One Sentence
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Microphone Sensitivity = The microphone’s natural loudness
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Audio Interface Gain = The amplifier strength matched to that loudness