Dynamic Range Compression: What Is The Makeup Gain Control?

Dynamic range compression is one of the most widely used and important effects/processes in audio production. The makeup gain controls within compressors help us to A/B the compression with great accuracy to make better mixing decisions.

In this article, we'll discuss the makeup gain control common to compressors to improve our knowledge of compression and how to use it appropriately in our audio projects.

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A Brief Discussion On Audio Dynamic Range Compression

Before we get into the makeup gain of a compressor, let's discuss dynamic range in a general context to understand why a compressor would benefit from makeup gain in the first place.

What is dynamic range compression? Dynamic range compression is the process of reducing the dynamic range of an audio signal (the difference in amplitude between the highest and lowest points). Compression does so by attenuating the signal amplitude above a set threshold point.

By reducing the level of the loudest parts of an audio signal, a compressor will effectively compress/reduce the signal's dynamic range. The dynamic range, of course, is the total difference between the loudest and quietest parts of an audio signal/track.

To easily visualize the operation of a compressor, we can imagine an automated level fader. As the input signal surpasses a certain threshold amplitude, the fader will automatically duck the output level by a set amount/ratio. As the input signal drops back down below the threshold, the fader will automatically return to its original position at unity gain.

So then, a compressor reduces the dynamic range by making the loud parts quieter and leaving the quiet parts alone.

As was mentioned at the beginning of this article, compression is one of the most commonly used processes in audio. Its uses include, but are not limited to, the following:

• Maintaining a more consistent level across the entirety of the audio signal/track
• Preventing overloading/clipping
• Sidechaining elements together
• Enhancing sustain
• Enhancing transients
• Adding “movement” to a signal
• Adding depth to a mix
• Uncovering nuanced information in an audio signal
• De-essing
• “Gluing” a mix together (making it more cohesive)

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What Is The Makeup Gain Of A Compressor?

The makeup gain of a compressor is a gain stage that happens after the main compression circuit. In other words, it's a gain control that makes up for the gain lost during the compression process.

Typically, the makeup gain is set to bring the peak signal level of the output back up to what it was at the input. With the makeup gain set to equal out the peaks, we can hear the full effect of compression on the signal. Without makeup gain, the signal can often sound overly quiet, which tends to make it sound worse from a psychoacoustic perspective.

Makeup gain can be visualized with the following illustration. In this image, the threshold is represented by the red dotted line and the peak amplitude of the original signal is traced with a black dotted in each of the three versions of the signal.

So with makeup gain set properly, we can A/B the compressor (turn it on and off) and have a good idea of how it's affecting the audio signal.

If we wanted, we could even drive the makeup gain higher than “unity” to add character to the signal if the gain stage is particularly colourful.

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How To Set The Makeup Gain Of A Compressor

Allow me to state, right off the bat, that there is no one-setting-fits-all situation when it comes to compression.

For example, a master bus compressor will be much more transparent and “light” than a parallel “New York” style compression that completely crushes the dynamic range.

Similarly, there's no “right” way to apply makeup gain.

That being said, the typical rule of thumb when setting makeup gain is to level out the amount gain reduction in the compressor circuit.

If the compressor averages 3 dB of gain reduction, apply 3 dB of makeup gain. If there's 6 dB of gain reduction, set the makeup gain to 6 dB.

Matching the gain this way will allow for more accurate A/Bing, which, in turn, helps us hear the compressor's effect more precisely. Without makeup gain, the wet signal would sound quieter, which tends to trick our brains into thinking it sounds worse (especially in the context of a mix in which the compressed signal could get drowned out).

In most situations, I recommend starting with a ratio between 2:1 and 6:1, along with medium attack and release times. I also recommend setting the threshold to achieve 3 to 6 decibels of gain reduction and bringing the output up by 3 to 6 dB with makeup gain.

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Related Questions

What are the main controls of a compressor? The main controls/parameters of a dynamic range compressor are as follows (with links to in-depth articles):

• Threshold
• Ratio
• Attack Time
• Release Time
• Knee
• Makeup Gain

What is audio data compression? Audio data compression is the process of encoding digital audio information into fewer bits than the original signal/file, thereby compressing/reducing the file size. Data compression can be either lossless (eliminating redundant info) or lossy (eliminating unnecessary or “less-important” info).

Popular lossless audio compression formats include:

• FLAC (Free Lossless Audio Codec)
• ALAC (Apple Lossless Audio Codec)
• APE (Monkey’s Audio)
• OFR (OptimFROG)
• WV (WavPak)
• TTA (True Audio)
• WMAL (Windows Media Audio Lossless)
• Dolby TrueHD
• MLP (Meridian Lossless Packing)
• MPEG-4 ALS (Audio Lossless Coding)
• MPEG-4 SLS (Scalable Lossless Coding)
• RealAudio Lossless

Popular lossy audio compression formats include:

• Dolby Digital
• Dolby Digital Plus
• DTS Coherent
• MPEG-1
• MPEG-2
• MPEG-4
• MPEG-H
• Vorbis
• WMA (Windows Media Audio)