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Mixing with Multi-Band

Compression & Expansion


Spl Hawkeye Multi Meter Plugin Screenshot

Control over dynamics is essential when mixing. Two precision tools in the arsenal are multi-band compression and expansion. But what exactly are these processes and how can they revolutionize your mixes? In this article, we'll take a journey through the realms of multiband processing and its unique strengths and practical applications in various mixing scenarios.


Understanding multiband dynamics processing


Multiband compression and expansion are sophisticated siblings of their single-band counterparts. Rather than applying uniform compression or expansion to the entire audio spectrum, these tools divide the signal into distinct frequency bands, allowing precise control over each band. This precise control is multiband dynamics processing, allowing you to maintain the integrity of each frequency band.

Multiband Compression


fabfilter pro mb screenshot, 4 bands compression

Multiband compression, like its single-band counterpart, is designed to reduce the dynamic range of an audio signal. However, it does so selectively across different frequency bands. This is particularly useful when you want to address specific problems in your mix without affecting other elements. By taming peaks and enhancing sustain or body, multiband compression gives you the right tools to sculpt your mix.


Multiband Expansion


fabfilter pro mb screenshot, 3 bands expansion

Multiband expansion, on the other hand, expands the dynamic range, making quiet parts quieter and loud parts louder within individual frequency bands. This can help clarify and enhance the nuances of your mix, especially if certain elements are lost or need to stand out.


Benefits of multiband compression and expansion


Both multiband compression and expansion offer a number of advantages in mixing:


- Precise control: unlike single-band processing, multi-band tools allow you to focus on specific frequency ranges where problems exist or improvements are needed.

- Frequency-specific treatment: each frequency band can be individually compressed or expanded, ensuring that one band doesn’t affect the dynamics of another.

- Clarity and balance: by addressing problems on a per-band basis, you can achieve greater clarity and balance in your mixes without compromising overall sonic integrity.


Solving common mixing scenarios with multiband processing


Let's look at five common mixing scenarios and how multiband compression and expansion can help you solve them:


1. Taming harsh vocals


Harsh vocals can sometimes cut through a mix and cause listener fatigue.


fabfilter pro mb, single band compression

Solution: Apply multiband compression targeting the upper midrange. Set a moderate threshold to gently reduce harsh frequencies while preserving the overall vocal character. Try a 2:1 ratio with a medium attack (15ms) and release (100ms) for a smoother performance.


2. Balancing the low end


The low end lacks definition, making your mix feel muddy.


fabfilter pro mb multiband plugin screenshot

Solution: Use multiband expansion to clarify the bass and kick. Focus on the sub-bass frequencies and set a threshold to bring out the quieter nuances. Use a 3:1 ratio and a fast attack (5ms) and release (100ms) to add punch without sacrificing warmth.


3. Controlling cymbal overload


Cymbals are often too present, overshadowing other elements.


fabfilter pro mb plugin screenshot, single band compression for cymbals

Solution: Use multiband compression in the high frequency range. Adjust the threshold to gently control cymbal peaks. A 2:1 ratio and a fast attack (3ms) coupled with a medium release (50ms) will give a balanced, transparent result.


4. Clarify electric guitar chords


Complex guitar chords get lost in the mix, affecting clarity.


fabfilter pro mb plugin screenshot, single band expansion

Solution: Apply multiband expansion to the upper midrange. Set a threshold to emphasise the subtleties of guitar chords. Choose a 4:1 ratio and a fast attack (10ms) and release (75ms) for definition without harshness.


5. Enhance piano dynamics


The piano in your mix lacks dynamics and sounds flat.


fabfilter pro mb plugin screenshot, single mid range band compression

Solution: Use multiband compression, targeting the mid-range. Adjust the threshold to gently increase the dynamic range of the piano. A 3:1 ratio, medium attack (15ms) and release (150ms) will breathe life into your piano performance.


Multi-band processing downsides and how to avoid them


While multiband processing is a powerful tool in the hands of a skilled mixer, it comes with its own set of challenges. Understanding these downsides is crucial for maintaining the integrity of your mix.


  • Phase Shifting Woes

Challenge: Processing different frequency bands separately can introduce phase shifts, leading to alignment issues.

Avoidance: Carefully choose multiband tools that minimize phase shifts. Also, consider using linear-phase processing if maintaining phase coherence is paramount.


  • Artifacts Between Bands

Challenge: Dividing your signal into bands might create artifacts at the crossover points.

Avoidance: Select multiband processors with advanced algorithms that minimize artifacts. Additionally, pay attention to crossover frequencies to mitigate any noticeable transitions.


  • Increased Complexity

Challenge: Managing multiple bands adds complexity to your mixing process.

Avoidance: Keep it simple. If multiband processing isn't essential for a particular element, consider using single-band techniques. Also, take advantage of presets to streamline your workflow.


Understanding these downsides empowers you to wield multiband processing effectively, overcoming challenges to achieve a polished and balanced mix.


Engineer’s tip: Masterful midrange control


As a bonus tip, remember that midrange control is often the key to a great mix. Whether taming harsh vocals or adding definition to electric guitars, multi-band compression or expansion applied to the midrange can significantly improve the clarity and balance of your audio. Experiment with different settings to find the sweet spot that brings your mids to life. Always use the multi-band processing in a sensible and tasteful way, do not overdo it and let the transients shine through.


Multiband compression and expansion are essential tools for audio engineers, offering pinpoint control over the dynamics of your mix. It takes time to master these techniques, but the results are well worth the effort. So enter the world of multi-band dynamics processing and unleash the full potential of your audio creations.

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