Learn How to Use Mix Bus Compression

Knowing how to use mix bus compression is essential for mixing audio. You can subtly enhance a track by controlling transients and dynamics, maximizing loudness, and gluing all of the individual elements together into a cohesive mix.

In this article, you'll learn proven techniques for mix bus compression that can be applied to any style or genre. For our examples we’ll be using one of our favorite mix bus compressors, the Manley Variable‑Mu, but you can achieve similar results with any compressor that features the same standard controls such as variable attack, release, threshold, sidechain filtering, dry/wet balance, and mid/side mode.

Let’s dive in and check out three different ways to harness the power of mix bus compression to take your tracks to the next level.

How to use Stereo Mix Bus Compression

Essential settings:

• Slow attack
• Fast release
• Sidechain filter enabled
• Moderate threshold
• 2-4 dB reduction

If you’re new to mix bus compression, this is the best place to start. These fool-proof settings will make almost any mix sound better by gluing things together while adding energy and increasing perceived loudness.

The slow attack allows transients to pass through, preserving dynamics and making the compression less obvious. Conversely, speeding up the attack lets you shape transients and grab on to the audio for more noticeable compression.

Many 2-bus compressors, such as the Manley Variable Mu, have a relatively slow attack speed. Even at the fastest setting, they’re typically still slower than compressors like the UA 1176.

A fast release setting lets the compressor recover quickly to maintain loudness and energy.

Reducing the release time will make the sound smoother and softer as more gain reduction is used. The signal will remain in a compressed state more consistently, without the compressor having a chance to recover between peaks.

Slower release times are often helpful on particularly dynamic mixes, when audible "pumping" can occur with faster settings.

The sidechain filter makes the compressor less reactive to low frequencies like kick drums and bass. This is important to maintain energy in the low end, and control the compression more precisely on other parts of your mix.

Tip:
If these settings are too subtle, try this variation:

• Lower the threshold for more gain reduction
• Speed up the attack for punchier transients
• Lower the mix knob to taste

How to Use Mid/Side Mix Bus Compression

Essential settings:

• Enable Mid/Side mode
• Unlink controls+sidechain
• Faster attack
• Slower release
• Lower threshold
• Increased output on side channel

Mid/side compression is used to control the dynamics of the mono “mid” elements of the mix separately from the stereo “side” elements, giving you precise control over your stereo image.

These settings let you keep the mono "mid" elements of the mix — kick, snare, lead vocals, etc — punchy and energetic, while keeping the "side" elements — stereo guitars, synths, overheads, reverb, etc — at a more consistent level to avoid pumping and other compression artifacts.

Boosting the output gain on the side channel makes up for the additional gain reduction and lets you increase the overall stereo width of the mix.

Stereo Mix Bus Limiting

Essential settings:

• Higher ratio
• Fast attack
• Fast release
• No sidechain filter
• High threshold

Limiting uses a higher ratio and a sharper knee so more reduction is applied to signals that cross the threshold. And the higher threshold setting ensures only the loudest parts of the signal are affected.

In modern terms, true “limiting” generally refers to any type of compression that uses a 10:1 or higher ratio, but this technique can be used with lower ratios as well — like the Manley Variable Mu’s “limit” mode, which ranges from 4:1 to 20:1 depending on how far the signal crosses over the threshold.

Hopefully these settings inspire you to try mix bus compression on your tracks, whether you’re looking to glue things together, fine tune your stereo image, or maximize loudness.

To learn more about compression, check out our Audio Compression Basics article.