How Condenser Microphones Work: The Definitive Guide
The microphone is one of the most important tools for any audio engineer. The type of microphone you use will determine the sound of the final product. There are three main types of microphones: dynamic, ribbon, and condenser. In this article, we will focus on condenser microphone and how condenser microphones work.
Quick Answer:
Condenser microphones work by using two metal plates to create a capacitor. When sound waves hit the capacitor, the movement of the air causes the plates to move closer together or further apart. This change in distance creates an electrical current, which is then amplified and converted into sound.
There are many different types of condenser microphones, each with its own unique design and features.
If you want to delve more deeply in knowing condenser mic, we have a guide to differences between condenser And ribbon microphone.
A condenser microphone is a microphone that is sensitive to the sound pressure waves that are introduced into the microphone. The sound waves are absorbed by the diaphragm, which converts them to mechanical vibrations. The vibrations are transferred through the frame and into the electrical circuit of the microphone. The electrical signal is then amplified and converted into an audio signal.
The two most common types of condenser microphones are electret and dynamic.
- Electret microphones use a permanent magnet to collect the electrical charge. This charge is not dissipated when the mic is turned off, allowing the electrical charge to last indefinitely.
- Dynamic microphones use an electromagnet to move an electrical charge that is collected on a coil. As the coil is moved by the sound, the charge is dissipated. The bigger the coil, the better the microphone is at picking up high-frequency sounds.
The condenser microphone provides a more accurate reproduction of the sound than a dynamic microphone.
How Does A Condenser Microphone Work?
A condenser microphone is an electronic microphone that works by creating a separation between the sound source and the microphone. And this separation is created by using a rubber diaphragm that moves in and out in front of the microphone’s sensitive element, creating a pressure differential between the front and back of the diaphragm. This pressure differential causes the diaphragm to move, which makes sound waves travel through the diaphragm and be picked up by the microphone’s sensitive element.
The diaphragm of a condenser microphone is typically made of flexible material (such as silicon) that will expand and contract when sound waves strike it. This is what causes the diaphragm to move. The diaphragm is set in front of the microphone’s sensitive element (often called a “diaphragm capsule”).
Diaphragms of Condenser Microphones
The diaphragm is the top part of the capsule. It’s usually made of a thin sheet of dielectric material, like plastic, though some condenser mics use a metal diaphragm. The diaphragm moves up and down with the sound waves, changing the distance between the two diaphragms, which changes the capacitance between them, which changes the voltage level. And this produces an electrical output.
This electrical output produced by the microphone is weak, so it needs to be boosted by a microphone preamp. The signal is then powerful enough to be processed by other devices in the studio – things like a mixing desk or an effects unit.
Large-diaphragm Condenser Microphone
The most common type of diaphragm found in condenser mics is the large-diaphragm mic. This has a dome-shaped diaphragm that is typically around one-and-a-half inches across.
A large-diaphragm condenser microphone is great for capturing the full spectrum of a guitar or a piano, because the large diaphragm allows the entire instrument to be heard. It doesn’t have the resolution of a small-diaphragm mic, but it has a greater sensitivity. In other words, the large-diaphragm condenser mic can pick up more sound.
Small Diaphragm Condenser Microphone
The microphone’s diaphragm may be as small as one-tenth of an inch.
Small-diaphragm condenser mics are used for capturing details and the highest frequencies and good for acoustic instruments like pianos and drums, but can be harder to use for vocals.
Phantom Power
Phantom power is a voltage bias that powers the microphone’s preamp. It’s usually around a couple of volts, which is enough to send a weak signal to the preamp.
Capacitor
A condenser microphone also has a variable capacitor in the microphone circuit. This capacitor creates some negative feedback which helps control how the diaphragm moves. The capacitor is not fixed in size, but instead has a small amount of resistance in it. The resistance of the capacitor is called the ‘Q’ factor. More ‘Q’ means a better capacitor.
The microphone circuit has a gain stage which adds some additional gain to the microphone signal as it gets sent to the pre-amp. The output of the pre-amp then goes to the recording device. The more gain is added to the signal, the easier it is to overdrive the recording device and it will be able to respond to a louder signal. The gain stage is controlled by a gain control knob.
Frequency Response
Transient Response
Transient response is the ability of a mic to capture the beginning and end of a sound. It’s important because it gives you good control over the transient-heavy sounds on your recording.
Transient response is measured in milliseconds and is often measured at around 40 to 120 ms. This is the time it takes for the audio to settle from its maximum volume to a quieter volume, and it’s important for vocals to have a good transient response.
Proximity Effect
Polar Patterns
A condenser mic’s polar pattern is the shape of the frequency response of the mic. This polar pattern can affect how the microphone is best used in a recording. An omnidirectional mic is a microphone that records sound from all directions equally. The omnidirectional polar pattern is a flat or narrow pattern, which is great for general recording. But if you want to get a bit more specific and focus on the sound of a specific instrument or voice, an omnidirectional mic may not be ideal. You’ll need to find a directional mic, which will give you a more directional response. A cardioid polar pattern is the best fit for vocals, electric guitars, and bass guitars. An isolating polar pattern is ideal for vocals and electric bass. Cardioid and isolating polar patterns can be used for recording acoustic guitars and other wind instruments.
Sensitivity / SPL / Noise
If a microphone is too sensitive, it will reject quiet sounds and the recording can become very quiet. A microphone that is too insensitive will not record fast transients and low-level sounds. If you have a sensitive mic that is too quiet, the sound will become distorted. If you have a microphone that is too loud, the sound will become distorted.
A microphone can’t record everything you make, because there are limits to the dynamic range of the recording device. You don’t want a mic that is too quiet, that will quickly clip into the recording. You don’t want a mic that is too loud, that will distort the recording of the quiet sounds. You want a microphone that is just right.
So the sensitivity of a microphone refers to how loud it can record. Most condensers will record from about 80dB SPL to 105dB.
The SPL of a microphone is measured in decibels. A mic with a higher SPL will pick up a wider range of frequencies in the recording, which leads to a more accurate recording. But this means that a higher SPL can also be very loud. The SPL of a mic can be measured using the SPL meter on the back of the mic. You can read more about SPL on our SPL meter page.
Noise is a buzz you hear in audio recordings. It can be the sound of the room, the wind, and electrical noise from the mics themselves, and can be a problem when recording vocals and acoustic instruments. A good condenser microphone will reduce the amount of noise in the recording, making it more pleasing to listen to.
A higher SPL value is good if you’re recording a live band or a loud PA system. The lower the SPL value, the less sensitive the mic will be to loud sounds. Generally, when you’re recording a vocal, you want to aim for a low SPL, so you don’t end up with a lot of distortion or clipping.
This is a measure of how ‘noisy’ the mic will be when recording a quiet environment. The lower the value, the more sensitive the mic is to noise. In general, the better the noise rejection, the higher the value.
Noise is usually most noticeable when you’re recording a quiet instrument or environment. In general, the lower the noise, the better. That’s because quiet environments or instruments are less likely to generate noise from the sounds themselves.
However, some instruments and environments do generate a lot of unwanted noise. For example, you might be recording a quiet acoustic guitar, but it’s sitting near a noisy hi-fi system. If you’re in that situation, you need to be picky about your mic and pick one that’s quieter.
That way, you can record the instruments without any unwanted noise from the surroundings.
The Components of Condenser Microphones
Condenser microphones are one of the most popular types of microphone used today. They are well known for their excellent sound quality and versatility.
Condenser microphones typically consist of three main components:
- A diaphragm
- A backplate
- An electronics capsule
The diaphragm is the part of the microphone that vibrates in response to sound waves. The backplate is the part of the microphone that helps support the diaphragm and also provides a place for the electronics capsule to be mounted.
The electronics capsule contains the circuitry that converts the vibrations of the diaphragm into an electrical signal.
Pros
- Very sensitive- able to pick up faint sounds
- Good at picking up high frequency sounds
- Can be used in a wide range of settings
Cons
- Sensitive to background noise and sound reflections
- Prone to distortion at high volumes
- Require phantom power
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