What Is A Condenser Microphone And When Should You Use One?

Martin Kristiansen

My name is Martin Kristiansen and I’m the founder and chief editor of HomeStudioIdeas.com. I’ve been playing, recording and producing music for the last 10 years.

Condenser mics stand out as the top choice for voice-over artists, producers, podcasters, singers, and other industry professionals – but why? Read on to learn what condenser microphones are, when you should use them, and situations where other microphone options might be better.

Pros & Cons of Condenser Mics

How Does a Condenser Microphone Work?

At its core, all condenser microphones use the same principle to create an audio signal. They convert an alternating capacitance to an alternating electrical signal, which is sent to the microphone’s output.

A condenser microphone is a type of capacitor microphone. It uses two metal plates (condensers) with an electric field between them to capture sound vibrations and convert them into electrical signals.

Several components play a vital role in converting the capacitance to an audio signal. I will explain each component in detail below.

The Components of A Condenser Mic

A condenser microphone is built with several parts and each component plays a vital role in the produced sound. The diaphragm is one of the most important pieces, as it picks up sound, vibrates, and converts it into an electrical signal.

The backplate and plates behind the diaphragm also play an important role in this process, as well as in how the microphone handles sound pressure levels. In addition, the body of the microphone houses various electronic circuitry that helps to amplify and modify the signal before it’s sent to your recording device or amplifier.

Capsule

The capsule is actually a group of components and should be considered the heart of a condenser microphone. It is a small piece of equipment that creates the electrical signals sent to the microphone’s output.

The capsule consists of two main parts that define the mic as a “condenser”:

The diaphragm is the most sensitive component of a condenser mic. It’s attached to a metal coil, and when sound waves hit the coil, it starts to vibrate. These vibrations create an electrical current, which is sent to the microphone’s output.

The backplate helps to protect the diaphragm from damage, and also helps to shape the sound that is produced by the microphone. Read more about the backplate below!

Also, there are many different types of capsules, each with its unique qualities.

Backplate

The backplate on a condenser microphone is a static metal plate that is located at the back of the microphone diaphragm. It remains still when the diaphragm vibrates.

The backplate helps to transfer electric signals from the diaphragm to the output. When the diaphragm vibrates, it creates air pressure differences between the backplate and the capsule. These variations in air pressure move the membrane closer or farther from the backplate, resulting in capacitance that is translated into an audio signal.

The backplate is also responsible for providing a ground connection for the capacitor. The design is important to maintain consistency in the sound quality of the microphone.

The plate also helps to improve the sound quality of the microphone by providing a flat surface against which to reflect sound waves. Additionally, it serves as a mounting point for various electronic components in the microphone.

Diaphragm

The diaphragm is located in the capsule, and functions as the membrane of the capsule.

The diaphragm is a thin metal or plastic sheet, positioned between two poles of a capacitor. It’s usually coated with gold to conduct electricity more efficiently.

When sound waves hit the diaphragm, it vibrates and causes the capacitor to change capacitance. As mentioned above, this change in capacitance is what creates the electrical signal that is sent to the microphone’s output.

Since the diaphragm has very little weight, it can generate some desirable performance characteristics over other types of microphones. It responds extremely fast to rapidly changing sounds (transients), which gives condenser mics a strong high-frequency response.

Impedance Converter

A condenser microphone also utilizes an impedance converter. Why? To increase the voltage of the electrical signal, generated by the vibrations from the diaphragm.

By default, the impedance is low at the microphone capsule and needs to be converted to the high impedance of the output connector. 

The impedance converter is a small electronic circuit board that is located in the body of the microphone. It is generally not visible, but it can be seen on some models.

Condenser vs. Dynamic Microphones

The most common types of microphones in home studio setups are condenser and dynamic. Each has its strengths and weaknesses, which is why they are used for different purposes.

A condenser microphone is typically better for capturing higher frequencies and detail. They also tend to be more sensitive than dynamic microphones, meaning they can pick up more ambient sounds.

On the other hand, dynamic microphones are better for live performances as they are less likely to pick up background noise. They can also handle higher sound pressure levels without distorting the sound or breaking the capsule.

Condenser microphones are also typically more expensive than dynamic mics, but they’re worth the extra expense. Due to increased sensitivity and better frequency response, condenser microphones are best for recording vocals, ambient sounds, and acoustic instruments.

Types of Condenser Microphones

Small diaphragm microphones and large diaphragm microphones are different types of condensers. They each have their unique characteristics that make them better suited for certain applications.

There are no hard-set rules and both condenser types can be used interchangeably. Still, there are some situations where you might want to choose a large diaphragm mic over a small diaphragm and vice versa.

As an example, small diaphragm microphones are typically more accurate and better at capturing transients. This makes them ideal for both drums and orchestral instruments such as strings and horns. 

When to Use a Large Diaphragm Condenser Microphone?

Large-diaphragm microphones usually color the sound by applying harmonic distortions to it. This colorization makes the sound richer and fuller. Also, the larger diaphragm captures low frequencies more effectively, making them ideal for vocals, piano, and bass.

Compared to small diaphragm mics, they offer a wider frequency response. This makes them ideal for sound sources with a lot of low-end frequencies.

Large-diaphragm condenser microphones are typically more expensive than their small diaphragm counterparts, but they often provide a higher quality of sound. They can also be more sensitive to noise, so care must be taken when using them in environments with high ambient noise or loud instruments.

For Vocals

Experienced sound engineers utilize a range of different microphones when recording vocals. Sure, you can use a dynamic microphone or a ribbon mic, but large diaphragm condenser microphones are by far the most used type for vocal recordings.

Why? As previously mentioned, large diaphragm condenser mics are superior when it comes to capturing low-end frequencies, and a small diaphragm condenser could produce a thin recording.

But that’s not the only reason. Large-diaphragm mics also offer a better noise performance, meaning that you’ll end up with a cleaner recording. It’s a challenge to remove noise in the post-production process without accidentally cutting high frequencies from the vocal performance.

Solo Acoustic Guitar

Apart from vocals, large-diaphragm microphones are also preferred when recording solo instruments. The vibrations from the larger diaphragm make the sound vibrant, full, and alive. If you record an acoustic guitar on its own with a small diaphragm mic, you could end up with a dull and thin guitar recording.

Additionally, large-diaphragm microphones are also known for adding a bit of color to the sound which makes it richer. Although some recording engineers prefer a more natural sound, the coloring makes it bigger which I prefer for solo instruments.

Acoustic Bass, Bass Guitar, Saxophones, Trumpet, Piano

Acoustic bass guitars, bass guitars, saxophones, trumpets, and pianos all have one thing in common – they all contain low-end frequencies. That’s why large-diaphragm microphones are preferred. A larger diaphragm can create heavier vibrations from low-end frequencies compared to small diaphragm microphones.

When to Use a Small Diaphragm Condenser Microphone?

Acoustic Guitars

Small diaphragm microphones are ideal when recording acoustic guitars that are part of a bigger composition, and not solo.

Since small-diaphragm mics have superior transient responses and are more capable of picking up transient sounds, the guitar strumming will be more prominent.

Actually, in modern pop music, it’s not uncommon for mixing engineers to mix acoustic guitars so that the pick attack is louder than the actual notes. This is preferred when guitars are part of the performance, rather than the whole performance.

Furthermore, the small diaphragm is more accurate in its sound reproduction which sometimes can be preferred for acoustic guitars. As mentioned above, large diaphragm mics alter the sound.

Piano

A full-sized piano contains seven octaves, ranging from the lowest of lows to the highest of highs. It’s a large and varied instrument that requires a microphone that can capture all frequencies evenly.

Small diaphragm microphones are much more accurate and can capture nuances better than large diaphragms.

Another core benefit is the much smaller pen-shaped size. Recording an acoustic piano often requires more than one single microphone. This makes small diaphragm mics a lot easier to place around the piano. They also capture the sound from the top rather than the side, making them easier to point directly over the piano’s strings.

Orchestral Instruments (Strings, Brass, Ensemble, Choirs, Bass) 

Orchestral instruments such as strings, brass, choirs, and upright basses are commonly used in classical music where authenticity is valued high. Listeners of classical pieces want to hear the sound in its natural state, without any colorization. That’s why small-diaphragm microphones are preferred.

Drums

Because of their superior transient response, small-diaphragm condensers are your best option when recording drums. Whether it’s a kick, snare, hi-hat, or tom – the sound is very explosive with strong transients. 

Just make sure that the microphone you plan on using can handle the high sound pressure levels of a drum set. There are specific condenser microphones for drums that can handle these loud hits without damaging the capsule, and still produce clear recordings.

Essential Things to Consider About Condenser Microphones

Sensitivity

When using a condenser microphone, keep in mind that they are very sensitive to movement and sound. They should always be used on a stable surface or mounted on a mic stand or boom arm. In addition, it is important to use a pop filter when recording vocals to prevent plosives from the singer’s mouth from entering the microphone.

They Require Phantom Power

Unlike dynamic microphones, condensers require phantom power to function. This is an additional piece of gear that needs to be considered when purchasing a condenser microphone. 

Phantom power is usually labeled as 48-volt on an audio mixer, audio interface, or preamplifier. The phantom power supplies voltage to the condenser microphone’s circuitry, which powers the microphone’s transducer.

The phantom power also supplies current to the microphone’s circuitry, which is necessary to bias the capacitors in the microphone.

They’re Fragile

Because of the thin metal plate and the more complex electronics in condenser microphones, they’re delicate and easy to break if not handled with care. While it’s not ideal to drop any type of microphone on stage or in the studio, dynamic microphones are more durable and are more likely to survive a drop than a condenser microphone.

Limit To The Maximum Signal Level

Condenser microphones can also be damaged beyond repair if the signal level is too strong (sound being too loud). If you’re recording a kick drum or a snare, make sure that you use a specific mic built to handle that kind of sound level and sound pressure.

Air bursts from plosive sounds can also degrade a condenser mic over time. Remember to use a pop filter to protect your microphone against the long-term degradation caused by exposure to plosive sounds.

Condenser Microphones Have Self-Noise

If you compare recordings from a dynamic microphone with a condenser mic there is a good chance that there is a lot more noise in the condenser. That’s because a condenser microphone has an internal noise floor, often called “self-noise.” The source of this inherent noise, or “hiss,” is the electronic circuitry within a condenser microphone.

It’s expensive to develop, design, and manufacture a condenser microphone with a very low noise floor. Therefore, cheaper models usually have a higher noise floor, sometimes measuring up to 30 dB SPL-Al. Check the noise floor specifications on inexpensive condenser microphones, and try to find one that is under 10 dB SPL-A. 

Conclusion

Condenser microphones are a must-have in every producer’s toolbox. This is especially true if you’re recording vocals, acoustic instruments, drums, or other sounds that need to be captured with clarity.

Generally, they’re more expensive than dynamic mics, but they provide recordings with much higher frequency response and detail. Also, cheaper condensers have a higher internal noise floor, generated by the electronic circuitry within.

However, there are some disadvantages you should consider before purchasing a condenser mic. They are extremely sensitive to noise so if you’re planning to record instruments, make sure that you have access to a silent recording environment.

They also require phantom power to boost the low output signal, meaning it’s not enough to only purchase a condenser mic. Phantom power can be activated on devices such as audio interfaces, preamplifiers, or mixers.

I hope you now have a good understanding of what a condenser microphone is. If you have any specific questions that I didn’t answer – let me know in the comments below!