Types of Audio Compressors

If you are new to Sound engineering or Music Production, you need to understand the concept and types of audio compressors. Audio compression is a simple yet critical technique used commonly to control the dynamics of a track which different types of audio compressors can achieve. In today’s blog post, we will discuss audio compressors and the pros and cons of several types of audio compressors.

What Are Audio Compressors?

Audio Compressors help technicians like us control any audio signal's volume and overall balance. This technique reduces the dynamic range of an audio signal, which in simple words, is the difference between the loudest and softest parts of any track.

Audio Compressors allow music producers and sound engineers to make the quieter parts of the track more audible and the same time manage to keep the louder parts of the recorded track under control. With years of development in the music production industry, different compressors are available in the market. Today, we have mentioned five of the most important types of audio compressors.

VCA Compressors

Voltage Controlled Amplifier (VCA) compressors are one of the music industry's most commonly used audio compressors thanks to their fast response time and transparent sound.

As their name suggests, these types of audio compressors do their job by controlling the gain of an audio signal through a voltage-controlled amplifier (VCA). The incoming audio signal in a VCA compressor is analyzed by a voltage control signal generated by the compressor’s sidechain.

Pros

Fast Response Time

One of the most important reasons behind using VCA compressors is their fast response time and hence are most commonly used on instruments like drums, bass, and guitars or instruments with fast transients, allowing them to be used for live sound applications.

Transparent Sound

These compressors don't add much color or character to the original audio signal, which allows the music producer to use them on a wide range of audio sources.

Cons

Lack of Character

While being able to produce, transparent sound is considered a pro by many, not being able to add a certain amount of tone to the track can also be a bane as it can result in a lacking character.

Limited Control

VCA compressors are infamous for providing only a limited level of control to the sound technician, which can be an issue for those engineers who want to own a certain level of control while compression.

Optical Compressors

Optical compressors use a light source, most commonly an LED, along with a photoresistor to control the gain of an audio signal. The LED is activated as the audio signal exceeds a set level, reducing the light reaching the photoresistor. This process is what reduces the gain of the audio signal.

Pros

Vintage Sound Feel

Optical compressors are used by music producers who want to add a specific tonality of character to their music. This tone gives the track a feeling of a vintage vibe when used on vocals or acoustic guitars.

Slow Attack Time

Optical compressors are known to have a slow attack time, allowing users to smooth out the overall dynamic range of a recording.

Cons

Slow Release Time

While we consider Optical Compressors to be one of the best types of audio compressors, many might feel different as they are not the best to control the decay of a note. This is why Optical compressors might not work well with instruments with fast transients.

Field Effect Transistor (FET) Compressors

FET Compressors as their name suggests, use a transistor to control the gain of an audio signal. They are known for their fast attack times and aggressive sound hence are often used with instruments like drums, bass, and electric guitars.

Pros

Aggressive Sound

FET compressors are most commonly known for their aggressive sounds, allowing users to add a certain amount of warmth and depth to a recording. One of the coolest and most useable things is its ability to add a subtle distortion to the original audio signal.

Fast Attack Time and High Gain Handling.

Fast Attack time makes FET audio compressors perfect for handling tracks with a higher dynamic range, energy, and fast transients. Also, their ability to handle high levels of gain along with Fast Attack time allows them to be used in rock and metal music.

Cons

Limited Versatility

It is a well-known fact that FET compressors are mainly used on instruments like drums, bass, and electric guitars, but because of their inability to manage slow transients, these compressors are not great for other instruments, hence their limited versatility.

Inconsistent Performance

With a limited ability to control their performance, FET Compressors are slightly variable in producing the desired effects, which takes away their chances of being used in live sound applications, where consistency is an unavoidable element.

Tube Compressors

Tube compressors are one of the oldest types of audio compressors. These audio compressors, unlike other compressors, use vacuum tubes to control the gain of an audio signal.

Once you use these compressors, you will understand that because of their ability to add certain warmth and depth, tube compressors are ideal for use in mastering applications.

One of the unique features of tube compressors is their ability to add harmonic distortion to an audio signal. This can help to add color and character to a track and can also help to make it sound more lively and dynamic.

Pros

Harmonic Distortion

Because of their ability to add harmonic distortion to the audio signal, Tube Compressors can create a more musical, natural, and human sound.

Versatile

Unlike most types of audio compressors, Tube compressors are extremely versatile tools because of their capability of usage with a wide range of audio sources.

Cons

Expensive and High Maintenance

Tube compressors require frequent tube replacements and deep cleaning, which is time-consuming. Also, in most markets, tube compressors are often more expensive than most types of audio compressors, limiting the ability to use these compressors if you are a beginner or someone with a tight budget on a particular project.

Heavy Weight and Bulky

If you have ever seen a tube compressor, you will understand what we are discussing. These types of audio compressors are usually heavier and bulkier compared to other generally used compressors, making them a logistical nightmare.

Voltage-Controlled Amplifier Compressors

Voltage-Controlled Amplifiers, more commonly known as VCA compressors, are analogue compressors that utilize a VCA chip which includes solid-state components such as transistors and integrated circuits to reduce the gain of the track.

Through the VCA chip, each audio signal is stripped into two paths, the main signal path and the sidechain path, which is then used to detect the level of the audio signal. The sidechain path is connected to a threshold control, which will decide the threshold at which it starts compressing the incoming audio signal. When this level is exceeded, the compressors start reducing the gain of the main signal path, resulting in compression.

Pros

Level of Control

Because of the integrated VCA chip, these types of audio compressors allow the users to have greater control than most audio compressors in the market. The level of control they offer about the gain reduction makes them a great choice for EDM and hip-hop genres of music.

Fast Response

Again, because of the chip and high-quality transistors, these compressors respond quickly, making them a great choice for live sound or other broadcast applications when manual adjustments are next to impossible.

Low Noise

With lower noise levels than typical audio compressors, VCA compressors can be used to increase the overall volume of a mix without adding unwanted hiss or hum, which plays a critical role in producing tracks that sound professional and rich.

Cons

Lack of Warmth

Like other types of audio compressors in the list, VCA compressors are both a boon and a bane as some music producers might feel they lack warmth and character because of the in-built solid-state components, which might make the sound feel a little digitized.

Artifacts

From my experience, at times, I feel that VCA compressors might add some unwanted pumping or breathing to the track after the audio compression. While this pumping and breathing might not be audible in all cases, at the end of the day, it is an unwanted element in the track.

Cost

Because of the use of high-quality solid-state components like an integrated circuit and transistors, depending on where you live, professional VCA compressors can be quite expensive, even for the reliability and control they provide.

Conclusion

In conclusion, we can say that all these different types of audio compressors have unique pros and cons. While VCA compressors are great for most occasions because of their fast response time and transparent sound, they lack certain characteristics and control. Optical compressors offer a warm, vintage sound but may have limited control and slow release times with all audio compressors.

After our thorough research for this blog and our years of experience, we can conclude that the type of compressor you should choose depends on your needs and preferences. Remember your audio source, your environment, and most importantly, the effects you want to create because it will decide the sound you will achieve.

♥ - Joseph SARDIN - Fondateur et Sonothécaire de BigSoundBank.com et LaSonotheque.org - Contact