In this blog post, we’re going to discuss how an audio compressor works. An audio compressor is an essential tool for anyone looking to get a professional sound out of their recordings. We will also explore popular types of audio compression, common mistakes that are made as well as some of the best audio compressors you can use for your recordings.
I. Introduction
1. Definition of audio compression
Audio compression is the process of reducing the dynamic range of an audio signal, which refers to the difference between the loudest and quietest parts of a sound.
It helps to prevent audio signals from becoming too loud and distorting, while also bringing up the quiet parts to make the sound more consistent and balanced. It is achieved by using a compressor to automatically reduce the gain of the audio signal when it exceeds a certain threshold level.
In other words, audio compression helps keep the volume of an audio track (vocals, song, etc.) more consistent, without any big spikes or drops. This makes the sound smoother and more enjoyable to listen to.
2. Brief history of audio compression
In the early days of radio broadcasting, audio compression was used to control the dynamic range of live performances and ensure that the audio was consistent and didn’t exceed the technical limitations of the broadcasting equipment.
In the 1950s and 1960s, analog tape recording became popular and audio compression was used to control the dynamic range of recordings and prevent distortion. The advent of digital audio in the 1980s and 1990s brought new opportunities for audio compression, as digital processing allowed for much more precise and effective compression algorithms.
With the widespread use of MP3s and other digital music formats in the 1990s and early 2000s, audio compression became a critical component of digital music, as it allowed for efficient storage and transmission of audio files. New developments in audio compression technology, such as lossless compression and high-resolution audio, are helping to push the boundaries of sound quality and make audio compression an even more important tool for shaping and controlling the sound.
II. What is an audio compressor & how does it work?
An audio compressor is a device used to reduce the dynamic range of a sound signal by compressing the signal and reducing the volume of the loudest parts while increasing the volume of the quietest parts.
This allows for a more even overall sound and helps to avoid distortion. Compressors can be used to shape the sound of a track, adding presence and clarity to the overall mix.
Nowadays, there are software versions called VST Plugins which are affordable and convenient compared to the hardware. They can be installed in your computer if you’re using a DAW (Digital Audio Workstation).
The sound of a compressed audio signal is then shaped by the parameters of the compressor, such as the threshold, ratio, attack, release, and make-up gain. Let’s take a look at some of these parameters in detail.
- Dynamic Range: Dynamic range refers to the difference between the quietest and the loudest parts of an audio signal. In audio compression.
- Threshold: Determines when the audio compressor starts to reduce the gain of the audio signal.
- Ratio: Determines how much gain reduction is applied to the audio signal when it exceeds the threshold.
- Attack and Release: Controls how quickly the compressor reacts to and releases from the audio signal that exceeds the threshold.
- Make-up Gain: Compensates for the reduction in overall level caused by the compression and restores the audio signal to its original level or even boosts it.
Once you’re familiar with the parameters, compressors can then be used in an audio setup by setting the threshold, ratio, attack, release, and makeup gain, and then adjusting the parameters as needed to get the desired sound.
III. Benefits of using an audio compressor
An audio compressor offers a number of benefits to the sound engineer, providing greater control over the dynamic range and overall volume levels of an audio signal. Used judiciously and in moderation, an audio compressor can greatly enhance the sound and bring out the best in a recording. The benefits of an audio compressor are as follows:
- Improved Consistency: Compression helps to reduce the dynamic range of an audio signal, making the loud and soft parts of the audio more consistent. This can result in a cleaner, more balanced sound.
- Increased Volume: By reducing the dynamic range of the audio signal, compression allows the overall volume to be increased without causing clipping or distortion. This can result in a more powerful and impactful sound.
- Enhanced Clarity: By controlling the levels of different elements in a mix, compression can help to bring out the important details in a recording and make it easier to hear all of the individual parts.
- Increased Sustain: Compression can be used to add sustain to instruments such as guitar, making solos and other performances sound more expressive and powerful.
- Improved Vocal Presence: Compression can be used to make vocal performances sound more present and up-front in the mix, allowing the vocals to cut through the other elements and be more easily understood.
- Better Control: By shaping the dynamic range of an audio signal, compression provides the engineer with more control over the final sound of a recording. This can result in a more polished, professional-sounding production.
- Improved Loudness: Compression can be used to increase the loudness of an audio signal, making it more impactful and attention-grabbing. This can be particularly useful in genres such as electronic dance music, where a loud and powerful sound is often desired.
IV. Popular Audio Compression techniques
Each type of compression below has its own unique advantages and applications, and different types of compression are used in different stages of the audio production process, from live sound reinforcement to mixing and mastering. Understanding the different types of compression and their benefits is an important aspect of audio production and sound engineering.
1. Peak Compression
Peak compression reduces the volume of the loudest peaks in an audio signal to prevent distortion and clipping. This type of compression is often used in live sound reinforcement to control the dynamic range of the performance.
2. RMS Compression
RMS compression reduces the overall volume levels of an audio signal by controlling the root mean square (RMS) level of the signal. This type of compression is often used in mixing and mastering to control the overall loudness of the audio.
3. Sidechain Compression
Sidechain compression uses a separate audio signal to control the compression of another audio signal. This allows for creative effects such as ducking, where the volume of one track is reduced in response to the volume of another track. This is often used in EDM or Electronic music.
4. Parallel Compression
Parallel compression, also known as “New York Compression,” is a mixing technique that involves blending the original, uncompressed audio with a compressed version of the same audio. This creates a sound that has the punch and clarity of the uncompressed audio combined with the consistency and volume of the compressed audio. Parallel compression is often used in music production to add impact and power to drum tracks, bass lines, and other elements of the mix that need to be more prominent and in-your-face.
5. Multi-Band Compression
Multi-band compression splits the audio signal into multiple frequency bands and applies separate compression to each band. This allows for more precise control over the dynamic range of different frequencies in the audio signal. Unlike traditional single-band compression, which processes the entire audio signal as a whole, multiband compression allows for more precise control over the dynamic range of the audio. This results in more accurate and natural-sounding compression, as only the specific frequency ranges that need to be compressed are affected, leaving the rest of the audio signal intact.
6. Transient Shaping
Transient shaping is a form of compression that specifically targets the transient parts of an audio signal, allowing for greater control over the attack and sustain of individual sounds. This can be used to make the sound appear more punchy, crisp, or lively, or to reduce the impact and sharpness of the sound if it is too aggressive or overpowering.
7. Bus Compression
Bus compression is used to control the volume of multiple audio tracks at once, reducing the dynamic range and making the mix more consistent in volume. A “bus” in audio terms refers to a group of tracks that are combined into a single, unified signal. The compressor acts on the combined signal, effectively controlling its dynamic range and ensuring that the levels of the individual tracks remain consistent and balanced.
8. Limiting
Limiting is a type of audio processing that involves the use of a limiter, a type of compressor with a high ratio and a fixed threshold. The purpose of limiting is to prevent audio levels from exceeding a certain level, or threshold, by reducing the amplitude of the audio signal whenever it exceeds that level.
V. Best Audio Compressor Plugins
1. Cyclone
The SoundSpot team wanted to create a truly diverse product that could be used across the board from mixing through to mastering, whilst also adding a distinct character to the sound if required.
With this in mind, the Cyclone was born. A compressor diverse enough to glue sub groups, add groove to vocals, percussion, warm up synths and guitars, and add the final touch of magic at the mastering stage. Also our algorithm and code are so precise and specific to the task at hand, that the Cyclone is super light on your CPU, meaning you can run multiple instances with ease.
2. smart:comp
smart:comp 2 automatically delivers transparent, precise results; providing you with the creative tools that will transform your sound from nice to extraordinary. This exceptionally versatile compressor is also packed with features that enable you to give any track a unique vibe including your vocals. Gradually shape the character of the compressor with the style dial and give your results a darker or brighter vibe using the color dial. The free-form transfer function with its templates allows you to achieve sophisticated level mapping. You can also fine-tune the temporal attack and release behavior without restrictions and apply a different compression to the ambience and center by using mid/side processing.
3. Mu
Pulsar Mu is a stereo compressor operating in either Left/Right or Mid/Side modes, designed with mixing and mastering applications in mind, but also flexible enough for tracking. It can be used for levelling, limiting, or just to add a bit of analog warmth with its emulated tube signal path. Another addition is the possibility of advancing (look-ahead) or delaying (look-behind) the sidechain signal. This enables you to take ultimate control over transients, letting the compressor start to react before they happen, over even after they happen, opening up all kinds of creative uses.
4. Fabfilter Pro-C
FabFilter Pro-C 2 is a high-quality compressor plug-in for the most demanding engineers. Whether you need subtle mastering compression, an upfront lead vocal, that magic drum glue or deep EDM pumping: Pro-C 2 gets the job done with style. Apart from the classic compressor controls, you also get smooth lookahead, up to 4x oversampling, intelligent auto-gain and auto-release, a variable knee, hold, range, external side-chain triggering, variable stereo linking and mid/side processing, all packed in a beautiful Retina user interface.
5. ShapeShifter
Inspired by SketchCassette’s NR Comp algorithm, ShapeShifter is a one-of-a-kind dynamics remodeler and character compressor that will completely transform the shape of your sounds. ShapeShifter moulds a blend of multi-band upward and downward compression into a toolbox for adding colour, body, and grit to your sounds. This can take the form of anything from a subtle vibe boost to blown-open, raucous carnage.
14 Best Compressor Plugins for Mixing & Mastering
VI. Common mistakes made using an audio compressor
An audio compressor is a powerful tool, but it is important to use it wisely and to avoid common mistakes Some common mistakes made using an audio compressor include:
- Over-compression: Over-compression can result in a “squashed” or “pumping” sound, with limited dynamic range and reduced impact.
- Not adjusting attack and release times: If the attack and release times are not adjusted appropriately, the compressor may be too aggressive or too slow in responding to changes in audio levels.
- Not considering the source material: Different types of audio sources, such as vocals, drums, or bass, may require different compression settings. It is important to consider the source material and adjust the compressor accordingly.
- Using too much compression: Excessive compression can lead to a lack of dynamic range and can make audio sound “flat” and uninteresting.
- Not using enough compression: On the other hand, not using enough compression can result in inconsistent audio levels, making it difficult to balance the mix.
- Using the same compression settings for all tracks: Different tracks may require different compression settings. Using the same settings for all tracks can lead to an inconsistent and unbalanced mix.
- Ignoring the stereo field: When compressing stereo signals, it is important to consider the stereo field and avoid affecting the balance between left and right channels.
- Not using compression in conjunction with other processing: Compression should not be used in isolation, but should be used in conjunction with other processing, such as equalization, to achieve the desired sound.
VII. Should I hire a mixing and mastering professional?
Hiring a mixing and mastering professional may be beneficial if you are inexperienced, working on a professional project, need specialized knowledge, or have limited time. An experienced audio engineer can help you achieve the desired sound and avoid common mistakes.
One of the best platforms online to find mixing and mastering professionals is Fiverr.
It’s a freelance platform that offers a wide range of services including mixing and mastering services. The main benefit is the cost savings. Additionally, Fiverr also offers a customer satisfaction guarantee so you can be sure you’ll get a good result. This means nobody gets paid until you’re happy with the results.
You can get started by visiting the link below to choose from a list of experienced mixing and mastering professionals, and see which one fits your needs.
VIII. Conclusion
An audio compressor is a crucial tool for shaping sound in digital audio production. By removing unwanted frequencies and reducing dynamic range, it can make a mix sound more polished, clean and professional. It can also be used to emphasize certain elements in a mix, such as vocals or drums, by boosting their levels. An audio compressor can also be used to make a mix sound louder, by increasing the overall gain of the audio signal. As a result, it is a key tool for achieving a desired sound in music production.
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