How does a condenser microphone work?
Long used in recording studios, condenser microphones have seen a boost in popularity recently, with the advent of vlogs and podcasts. This trend looks set to continue with so many people working and recording from home.
Condenser microphones are particularly suited to precision recording in studios, whereas other types of microphone are better at capturing a range of sounds (think recording a soloist vs. a church choir) or ambient sound. The way a microphone is built, from its general size to its diaphragm size and diaphragm type to its polar patterns (how it picks up sound), will affect the final result. The condenser microphone is specifically designed to produce a top-quality, nuanced recording in a controlled environment.
What is a condenser microphone?
The condenser microphone, also known as a capacitor or electrostatic microphone, was invented in 1916 by E.C. Wente, a Western Electric/Bell Labs physicist. What distinguishes a condenser microphone from other microphones is that it uses capacitance instead of moving coils to translate sound. Condenser microphones are built with a thin conductive diaphragm next to a metal backplate, which together form a capacitor. As sound waves vibrate the diaphragm, the vibrations produce changes in the distance between the plates, which alters the capacitance and produces an electric signal. This signal is recorded on a computer in real time using an XLR or USB cable.
By capturing sound this way, a condenser microphone is more sensitive, picking up every subtle sound in the environment and producing a rich, clear recording. This sensitivity makes it ideal for a controlled setting like a recording studio but ill-suited to a louder, real-world environment where capturing all sound would be overwhelming. In this case you would use a cheaper dynamic microphone which captures lower quality audio but can pick up a specific noise among many in a louder setting.
Condenser microphone features
Condenser microphones have a range of different features which are specific to certain applications. Some are essential and others are useful, but optional.
Diaphragm size
Like all microphones, condenser microphones contain a diaphragm that enables sonic energy to be converted into electrical energy. Since the vibration of the diaphragm is what determines sound quality, the size of the diaphragm will greatly affect the microphone’s sensitivity, range and ability to handle sound pressure levels. Condenser microphones with large diaphragms (diameter of 1 inch or more) produce a higher signal voltage and generate significantly less internal noise, resulting in a rich, rounded sound. Small diaphragm microphones (1/2 inch or less in diameter) are more responsive and precise, capturing a clear, neutral sound.
Audio output
Condenser microphones emit internal noise that can be detected by the microphone. Sometimes called “self-noise,” it is the sound of the electrical current that powers the device and can be measured in A-weighted decibels (dB-A). Most microphones measure in the 9-19 dB-A range, with those in the low range costing more.
Professional sound recorders tend to use XLR cables for audio output as they emit less internal noise and produce a cleaner sound. The less expensive USB microphones are becoming more popular, however, because the USB connection doubles as a power source and you can record directly onto your computer with them. Mini microphones (3.5 millimeter) also exist but are less prevalent due to poorer sound quality and the need for an additional power source.
Sound pressure level
Sound pressure level measures the decibels that a microphone can record. Maximum SPL is the highest level the device can tolerate before sound quality is compromised. Although not as durable as dynamic microphones, condenser microphones can record most sounds as long as the SPL isn’t higher than about 120 dB. For some applications, you may need a microphone that can tolerate higher-decibel sound.
Frequency response range
Condenser microphones are also available with different frequency response ranges. A microphone with a flat frequency range will pick up both high- and low-frequency sounds, which is ideal for recording several voices or instruments simultaneously. If you are looking to record one instrument or one voice, a microphone that’s more sensitive to specific frequencies would be better.
Cardioid or omnidirectional
Condenser microphones can be cardioid (directional) and capture sound coming into the front of the microphone exclusively, so you can point it towards the source of the desired sound and block out all other ambient noise. These types of microphone work well for live performance recordings. They can also be omnidirectional and take in sound from all directions, recording several instruments or voices at once. Some condenser microphones can switch between the two modes.
Accessories
Pop filter
Cardioid microphones can be vulnerable to “pop” noises, resulting from hard consonants like “P” and “B” hitting the diaphragm too forcefully. Some microphones feature a built-in filter to counter this phenomenon but you can also buy a pop filter or a windscreen relatively cheaply. It’s a worthwhile investment because it protects the microphone from loud noises and saliva.
Stand
You may need to purchase a microphone stand separately if your device doesn’t come with one. Stands can help mitigate unwanted noise and there are several different types, depending on your needs. A shock mount stand reduces vibrations, which is especially useful for recording vocals. A tripod stand is ideal for general usage. Desktop stands work well for recording podcasts or vlogs and overhead stands, a favorite of recording studios, offer a wide range of positions.
How much do condenser microphones cost?
All these variables mean that condenser microphones range greatly in price from $9-$1,200. You can find a decent microphone for general use in the under $50 category. Above that, in the mid-price range, are some high-quality microphones with lots of additional features. Professional-quality microphones, like those used in recording studios, will run to $250-$1,200 or more.
Bryony Gilbey is a writer for BestReviews. BestReviews is a product review company with a singular mission: to help simplify your purchasing decisions and save you time and money.
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