Fixing Problems Using Audio Compression: Tips and Settings

Audio compression serves as a powerful tool in music production and audio engineering. It transforms a mix from amateur to professional by addressing various issues and enhancing the overall sound. In this blog post, we'll explore how to use audio compressors to fix common problems, level performances, and bring out the best in your recordings. We'll also cover essential basics, compression settings, and common mistakes to avoid.

Understanding Compression Basics

Before diving into specific applications, you need to understand the basics of audio compression. An audio compressor reduces the dynamic range of a signal, making the quiet parts louder and the loud parts quieter. Several key parameters achieve this:

• Threshold: The level at which the compressor starts to act. Signals above this threshold get compressed.

• Ratio: Determines the amount of compression applied to signals above the threshold. For example, a ratio of 4:1 means that for every 4 dB above the threshold, the output only increases by 1 dB.

• Attack: How quickly the compressor responds to signals above the threshold.

• Release: How quickly the compressor stops acting after the signal falls below the threshold.

• Makeup Gain: Boosts the compressed signal to make up for the reduction in volume.

Leveling Performances

One of the primary uses of audio compression is to level performances. This ensures that all parts of a performance sound clear and consistent, whether it's vocals, drums, or other instruments.

Vocals

Vocal Example Settings

Vocals often serve as one of the most dynamic elements in a mix, with variations in volume and intensity. A well-applied compressor smooths out these dynamics, ensuring that every word remains audible without overpowering other elements.

Example Settings: Use a medium attack and release, a ratio around 3:1 to 4:1, and adjust the threshold until the vocal sits nicely in the mix.

Drums

Kick Example Settingsˆ

Drums benefit greatly from compression, which adds punch and consistency. For kick and snare drums, use a fast attack and release with a higher ratio to provide the desired punch. For overheads and room mics, use a slower attack to retain the natural transients and a lower ratio to maintain a more open sound.

Example Settings:

• Kick/Snare: Fast attack and release, ratio 4:1 to 6:1.

• Overheads/Room Mics: Slow attack, medium release, ratio 2:1 to 3:1.

Other Instruments

Bass Guitar Example Settings

Different instruments require different compression settings. For instance, bass guitars often need a slower attack and release to retain their natural sustain, while electric guitars might benefit from faster settings to enhance their rhythmic clarity.

Example Settings:

• Bass Guitar: Slow attack and release, ratio 3:1 to 4:1.

• Electric Guitar: Fast attack and release, ratio 4:1.

Using Compression to Enhance Low-Recorded Tracks

Enhancing Low Recorded Tracks

Sometimes, recordings might be too quiet or lack presence. Compression can help bring out these tracks by boosting their quieter parts. Set a low threshold to ensure the compressor acts on the entire signal, and use makeup gain to increase the overall volume. This technique adds warmth and presence to background vocals, acoustic guitars, or any track that needs a lift.

Example Settings: Low threshold, medium attack and release, ratio 2:1 to 3:1, use makeup gain to boost overall volume.

Additional Ways to Fix Issues in the Mix

Controlling Peaks

Uncontrolled peaks can cause distortion and make a mix sound unprofessional. By setting a fast attack time, a compressor catches and reduces these peaks, creating a more controlled and polished sound.

Example Settings: Fast attack, medium release, ratio 4:1 to 6:1, adjust threshold to catch peaks.

Enhancing Clarity

In a dense mix, some instruments or elements can get buried. Upward compression (parallel compression) enhances clarity by blending a heavily compressed version of a track with the uncompressed signal.

Example Settings: Duplicate track, apply heavy compression with fast attack and release, ratio 8:1 or higher, blend with uncompressed track.

Adding Sustain

For instruments like electric guitars, basses, or pianos, compressors can add sustain by keeping the signal level up for longer with a slower release time.

Example Settings: Medium attack, slow release, ratio 2:1 to 3:1.

Glueing the Mix

Mix bus compression applies gentle compression to the entire mix, helping all elements feel more cohesive.

Example Settings: Low ratio (2:1), medium attack, slow release, adjust threshold for subtle compression.

De-Essing

Harsh sibilance in vocal recordings can be tamed with a de-esser, which targets and compresses the specific frequency range where sibilance occurs.

Example Settings: Fast attack and release, ratio 4:1, frequency range 5-10 kHz, adjust threshold to reduce sibilance.

Pumping Effects

For creative purposes, compressors can create a "pumping" effect, often achieved with sidechain compression.

Example Settings: Fast attack and release, ratio 4:1, sidechain input from kick drum, adjust threshold for desired pumping effect.

Managing Dynamic Range in Live Recordings

Live recordings often have a wide dynamic range. Compressors help manage this by reducing the volume differences between the loudest and quietest parts.

Example Settings: Medium attack and release, ratio 3:1 to 4:1, adjust threshold to manage dynamic range.

Improving Vocal Intelligibility

Sometimes, vocals can be hard to understand. By using a compressor with a medium attack and release time, you can enhance the clarity and intelligibility of the vocals.

Example Settings: Medium attack and release, ratio 3:1, adjust threshold for clearer vocals.

Reducing Background Noise

In recordings with a lot of background noise, a compressor can reduce the prominence of this noise by setting a higher threshold so it only acts on the louder, desired parts of the signal.

Example Settings: High threshold, fast attack, medium release, ratio 3:1 to 4:1.

Conclusion

Compressors serve as versatile tools that address a wide range of issues in a mix, from controlling peaks and enhancing clarity to adding sustain and creating special effects. By understanding and experimenting with different compression techniques, you can solve many common mixing problems and elevate the quality of your productions. Remember, the key to effective compression is subtlety and precision—always listen critically and make adjustments as needed.