How Does A Condenser Microphone Work? ๐ŸŽ™๏ธ

If you’ve looked into making music, podcasting, or any other recording form, chances are you’ve heard of or seen a condenser microphone. This microphone is an excellent option for recording both instruments and vocals, but you might need clarification on exactly how they work.

A condenser microphone works by converting audio signals to electrical energy. It uses two charged metal plates to make a capacitor. As sound waves connect with the metal plate, they begin to vibrate within it. This movement produces an electrical signal that matches the sound source.

The rest of this article will detail a few topics related to this question, including what makes a conder microphone work, what they are used for, and some pros and cons of this microphone type. 

How Does A Condenser Microphone Work

How Condenser Microphones Work

Condenser microphones use vibrations produced by incoming sound waves to fluctuate the voltage of their internal parts. This fluctuation copies the pattern of the incoming acoustic energy to produce an electrical signal. 

To fully understand this mechanism, you must understand the function of the parts that make up a condenser microphone.

Its Capacitor System Converts Audio Signals Into Electrical Energy

Condenser or capacitor microphones get their name from the “capacitor” inside, which handles audio conversion into electrical energy.

The capacitor in a condenser is made of two parallel metal-surfaced plates placed close together, which allows voltage to be stored and run across them. This process is called capacitance.

CapacitanceOpens in a new tab. describes the ability of a component or circuit to collect and store energy in the form of an electrical charge. If the electrical charge moves between two uncharged conductors, both become equally charged (one positive and one negative), producing a potential difference between them or a voltage.

You measure the capacitance value of a capacitor in farads (named after physicist Michael Faraday). A farad is the largest quantity of capacitance. However, most common electrical devices use capacitors that only produce a fraction of a farad, called a microfarad (thousandth of a farad ) or picofarad (a trillionth of a farad).

Key Components of the Capacitor System

In a condenser microphone’s two-plate capacitor system, one is called a backplate, and the other is called a diaphragm. These two plates are housed inside a microphone capsule and are visible if you remove the microphone’s grille. The sound capture part of a condenser microphone is typically called a capsule.

  • Backplate. The back plate is immobile and usually constructed of solid brass. Although it is fixed in place, the backplateOpens in a new tab. is often perforated (pierced with one or more holes), which allows air to pass through it. These partially drilled holes alleviate the pressure produced by the natural resonance of the diaphragm.
  • Diaphragm. On the other hand, the diaphragm is a mobile piece and is typically made of more lightweight metals or from mylar, with a thin gold coating to allow electrically conductive. The diaphragm works like a drum skin,Opens in a new tab. resonating vibrations and sound waves. Its job is to identify subtle changes in air pressure made from the sound of vocals, instruments, or the room itself that is being recorded.

Condenser Mics Require an Outside Power Source

Other key parts include the impede converter and power supply. Condenser mics typically don’t generate enough voltage on their own and require help to raise their low currents. The impedance converter’s role is to boost the electrical signals generated by the capacitor.

Unlike dynamic microphones, condenser mics require an outside source to power. Depending on the microphone, this can come from an audio interface through the use of an XLR cable or from a separate device like a PC or laptop through a USB port. This process is typically called phantom powering or phantom power.

If you’re looking for a more detailed look at the inner workings of these microphones, this video does a great job of breaking it down.

Types of Condenser Microphones

Although it is a very distinct type of microphone, condenser mics come in a wide variety. Typical condenser microphones are split between diaphragm size and capsule polarization. 

Small-Diaphragm vs. Large-Diaphragm Condensers

The most common difference between condenser microphones is the sizeOpens in a new tab. of their diaphragms.

While the basic functionality will be similar, different size condensers typically have unique performances and specializations.

Size

A large diaphragm condenser typically has a diaphragm with a diameter equal to 1 inch (25.4 mm) or more. A small-diaphragm condenser has a diaphragm diameter of 1/2 inch (12.7 mm) or even less.

It’s important to note that even though these diaphragms have different sizes, they both use the same fundamental capacitor system, including a static backplate, mobile diaphragm, and need for an external power supply.

Although they have the same base functionality, their sizes give them unique differences, including transient response, frequency response, and polar patterns. 

Transient Response

Transient response determines how accurately a microphone reacts to transient audio present in its diaphragm. TransientsOpens in a new tab. are small high-energy sound bursts typically found at an audio source’s beginning. The loudest and most apparent transients come from percussion-based instruments but can be found in string instruments and horns.

Large-diaphragm condenser microphones typically have slow but very accurate transient responses. Their bigger size hinders these microphones’ ability to react to transients quickly. However, they still do a great job of creating proper audio reproduction. 

Small-diaphragm condenser microphones are designed to have fast transient responses meaning they can react to transients exceptionally quickly. Their transient response level makes them one of the most precise microphones available. Although uncommon, some smaller ones are too fast and will overreact to transients causing an inaccurate capture. 

Frequency Response

Frequency response refers to the total range of frequencies and tones a microphone can recreate. Better frequency response means the audio components are better at recreating sound waves with minimal to no changes.

Both large-diaphragm condenser and small-diaphragm condenser microphones have flat frequency responses making for accurate reproduction. Large condensers generally have a fall-off at higher rangers creating a bright or even harsher sound. 

Small condensers don’t experience these resonant cancellations and, as a result, have a cleaner sound even above human hearing ranges.

Pattern Style

Polar patterns refer to the direction of the microphone from which it records sound best. The most common directional polar patternsOpens in a new tab. include cardioid, hyper/super cardioid, bidirectional, and omnidirectional.

  • The cardioid pattern is the most common and typically used when you only want to record one source at a time. They are named after their heart-shaped pattern and focus on sound from the front of the mic, reducing noise generated from the side and rear of the device. 
  • Hyper-cardioid and supercardioid polar patterns are cardioid shapes with an even stricter focus on recording from the front, picking up even less sound from the sides and rear. A shotgun microphone is another directional device with an even shorter range. They are commonly used in film and TV sets that don’t require long-distance audio capture. 
  • Bidirectional or figure-of-eight polar pattern refers to microphones that pick up sound from the front and rear equally but block capture from the sides (making an โ€œ8โ€ shape). They produce a more natural sound as they capture both the source and ambiance from the room itself. 
  • Omnidirectional microphones are designed to pick up sound from all directions of the microphone making a circle shape. These microphones are best at capturing the most natural and realistic audio possible. These mics are great for recording multiple people at once or when you want to incorporate the area’s sound into the recording. 

Large-diaphragm condensers typically have a multi-pattern style that allows them to match multiple polar patterns by mixing different polarities and amplitudes. Their polar pattern can change at different frequencies, becoming more omnidirectional at lower levels while becoming more narrow at higher frequencies. 

Small-diaphragm condenser microphones’ polar patterns tend to be more consistent, maintaining their patterns across various frequency levels. Their size is consistent and lightweight, making them ideal for shotgun microphones.

Self-Noise

Self-noise refers to how much noise or feedback is produced while it is in use. Due to their active components, all types of microphones have some level of self-noise, just at varying degrees. Limiting outside noise as much as possible is crucial when recording the desired audio, and as such, mics with lower self-noise are often preferred.

On average, large-diaphragm condensers have lower self-noise levels than small ones. Large condensers can house much stronger audio signals giving them a more excellent signal-to-noise ratio compared to small condensers with the same quality of components. 

However, small diaphragm condensers typically beat large ones in all other major categories. 

Price and Use

In terms of price, large-diaphragm condensers also tend to be much more expensive than small 

ones.

As far as uses go, large diaphragm condensers are typically used for recording voices, groups, acoustic guitars, and pianos. They are best for picking up the ambiance of the recording room. Small diaphragm condensers are better for recording instruments overall. 

Electret Condenser

Besides size, condenser mics are grouped by their polarization. While typically, condenser microphones require an outside source to establish a charge, Electret condensers 

have a permanent electrical charge by utilizing an electret film. 

Electret film is an electrostatic magnet that removes the need for a high-voltage power supply. Like other condenser mics with a polarized capsule, an electret condenser has small and large diaphragm sizes. 

Pros and Cons To Consider

Due to their unique design, condenser microphones come with very distinct strengths and weaknesses.Opens in a new tab.

Pros

Some of these advantages include the following:

  • A wide-frequency response. With a wide frequency, condenser mics can record a wide range of decibels. This sensitivity allows them to obtain subtle and more nuanced audio with better quality than other kinds of microphones.
  • High-quality sound. The capacitor inside a condenser mic has a high transient response allowing it to reproduce high-quality, clear sound free of distortion. 

Cons 

Although they have apparent strengths, condenser mics come with some significant issues.

  • They have delicate components. Although their sensitivity helps them pick up intricacies in sound, it always makes them adverse to loud noise. Loud audio can overwhelm and even damage these microphones leading to audio disruption. This makes them a poor choice for live recordings.
  • A reliance on phantom power. As mentioned previously, unlike dynamic mics, condenser microphones lack an internal energy source and must get power externally. Meaning you will need to purchase another device to begin recording. 
  • Typically more expensive. Although condenser mics are famous for their superior sound quality, they come at a higher price than other microphones. Their price and need for a separate power supply can make purchasing one a significant investment. However, there are more affordable versions available.

When To Use a Condenser Microphone

With such high sensitivity and audio quality, conders microphones work in various tasks, including vocal and instrumental recording.

Typically a condenser microphone is the best used for recording human voices. Since these mics can pick up more details and nuance in human speech, they are perfect for conveying and enhancing vocal performances. Their sensitivity makes a world of difference where the subtleties matter more, like voice acting, podcasts, music vocals, and audiobooks. 

Although live performances like concerts aren’t ideal for condenser microphones, more conversational work like recording audio for television and film is perfect. They are fantastic for capturing the performance but typically won’t produce enough sound waves to harm the microphone.  

Even though these mics aren’t built for loud instruments like drums, horns, and amps, they work well to capture more ambient sounds from acoustic instruments. Just like with vocals, a condenser mic is unmatched at capturing the nuisances in the sound of instruments like autistic guitars, shakers, and tambourines. 

Conclusion

Like all microphones, condenser mics take sound waves and vibrations and convert them to electrical signals. Condenser microphones use a sensitive two-plate capacitor system, allowing them to produce higher-quality audio from a wide range of frequencies. 

Although great for finding the nuance in audio, the delicate nature of these devices makes them unequip for recording live, noisy instruments. They also rely on phantom power, meaning they do not produce their own energy and require an external power supply. 

Sources 

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Vinnie

I'm Vinnie, and I'm here to support you to create your own studio at home, whether itโ€™s for photography, recording audio, podcasts, or videos!

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