Microphones convert sound waves into electrical audio signals so we can record the sound or broadcast it through different mediums. However, converting acoustic energy into electrical energy isn’t sufficient since the signal has to be strong enough to be audible. The gain on a preamplifier boosts the strength of a microphone’s output signal, but will some mics require more gain than others?
Microphone sensitivity greatly affects the gain needed for a mic’s output signal to become audible. The gain on a preamp must be set so the sound is loud enough without distortion. Unlike condenser mics with higher sensitivity, dynamic mics typically have lower sensitivity and require more gain.
Keep reading to get the best sound possible from your mic. This article will explore the characteristics of dynamic mics while explaining the relationship between microphone sensitivity and gain.
Table of Contents
- Why Dynamic Mics Need More Gain Than Condensers
- The Difference Between Dynamic and Condenser Mics
- Microphone Sensitivity and Gain
- How To Set Microphone Gain on a Preamp
- Final Thoughts
Why Dynamic Mics Need More Gain Than Condensers
Generally speaking, dynamic microphones have lower output levels than condenser mics. The output level determines the audio signal’s strength before it’s passed on to a preamp. A microphone preamp controls gain, which boosts the audio signal’s amplitude.
Dynamic mics require more gain since their output signal is weaker than condensers. The disparity in the strength of the output signal between dynamic and condenser mics exists because each mic works differently despite having the same essential function.
Knowing how each mic works will help you better understand why they perform differently.
The Difference Between Dynamic and Condenser Mics
Dynamic and condenser mics share the same task of converting sound waves into electrical signals, but each mic accomplishes this task differently. The difference between the two mics lies in their transducer properties; one uses electromagnetism, while the other works with variable capacitance.
Dynamic Mics
Dynamic mics have a diaphragm that vibrates when it encounters sound waves. The vibrations cause a conductive coil to move, and since a magnetic field surrounds the diaphragm and coil, the sound wave is converted into an electrical audio signal.
Dynamic mics are passive since they do not need an external power source. The conductive coil amplifies the electrical signal inside a dynamic mic, which gives it a lower output signal.
Below are more characteristics of dynamic mics:
- Dynamic mics are less sensitive, so they can absorb higher sound pressure levels before distortion occurs.
- Due to their low sensitivity, dynamic mics are less prone to picking up the background noise.
- Despite the lower noise levels, dynamic mics generally do not sound as good as condensers due to their limited frequency response.
- Most dynamic mics have a cardioid polar pattern, where sound is absorbed from the front of the mic.
- Generally speaking, dynamic mics are more affordable than condenser mics.
Condenser Mics
Condenser mics contain two conductive plates that form a capacitor. Like the dynamic mic’s diaphragm, sound waves cause the thin and flexible front metal plate to vibrate. In turn, the front plate moves a magnetic plate to create a duplicate of the sound waves in the form of an electrical audio signal.
Unlike dynamic microphones, condenser mics need an energy source to boost the voltage to produce a signal. The energy source usually comes from a phantom power supply, but some condenser mics also have internal batteries or get power from a USB connection.
A condenser mic’s reliance on a power source gives it a higher signal output than a dynamic mic.
Below are more characteristics of dynamic mics:
- Since condenser mics are more sensitive, they can pick up more sound but are also more prone to noise and distortion.
- Condenser mics have a broader frequency response giving them more accurate and clearer sound quality.
- Condenser mics can pick up sound from almost any angle, and some even allow you to customize their polar pattern.
- Condenser mics are relatively more expensive than dynamic mics.
If you’re a streamer, you’re probably stuck between choosing dynamic and condenser mics for streaming work. The choice depends on your specific environment. Find out how in my complete guide. Do Streamers Usually Use Dynamic or Condenser Mics?
Microphone Sensitivity and Gain
Microphone sensitivity indicates how strong a microphone’s output signal is per sound unit. So, a microphone with higher sensitivity will have a stronger output signal than one with low sensitivity, but that doesn’t necessarily make it a better mic.
Microphones with low sensitivity work better in specific scenarios.
A microphone’s sensitivity greatly determines the output signal strength, but it’s not the only factor.
Other factors that affect the strength of a microphone’s output signal include:
- The loudness of the sound source.
- The placement of the microphone.
- The amount of gain applied to the signal from the preamp.
There may be a variance in the output signal strength across different microphones, but the typical power output of mics is called mic level. Line level refers to the standard signal strength used in professional audio gear.
The gain on a preamp boosts the output signal from microphones from the mic level to the line level. You have to apply more gain to reach line level with dynamic mics that have low sensitivity. Another option to increase output is by placing the mic closer to the sound source or making the sound source louder.
How To Set Microphone Gain on a Preamp
Just because we’ve established that dynamic microphones typically need more gain than condensers, it doesn’t mean that you should crank that gain knob up. Applying too much gain can cause some nasty distortion.
You must check your preamp’s VU meter or the level meter on your DAW to set the right amount of gain for your mic. To prevent distortion, the VU meter should remain below 0, no matter how loud the sound source gets.
Microphones have a vast dynamic range, so there is usually a significant difference between the faintest and loudest sounds they pick up. When doing a sound check, try to replicate the loudest possible sound your mic will pick up to prevent going beyond 0.
Setting the gain low is always better than setting it too high.
Final Thoughts
Dynamic mics generally require more gain than condensers since they typically have lower sensitivity and outputs. However, other factors like placement and the loudness of the sound source also determine a microphone’s output level, so the amount of gain needed can vary.
Regardless of what type of mic you use, you should always do a sound check to ensure you apply the right amount of gain.
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