Multiband compression and dynamic EQ are both effect plug-ins that are used to control and shape the dynamics of audio signals, but they differ significantly in their functionality and application.

Multiband compression:

• Frequency subdivisions: With multiband compression, the audio spectrum is divided into several frequency bands, usually three or more. Each band can be processed separately.
• Dynamic control: It applies compression independently to each frequency band. This means that you can control the dynamic range (the difference between the quietest and loudest parts) of different frequency ranges separately. For example, you can compress the bass frequencies without affecting the mid or high frequencies.
• Thresholds and ratios: With multiband compressors, you can set individual thresholds and compression ratios for each frequency band. This allows you to control exactly how much compression is applied to each part of the spectrum.
• Crossover filter: In multiband compression, crossover filters are often used to divide the signal into frequency bands. These filters determine the boundaries between the bands and can be linear-phase or minimum-phase, which affects the phase response of the audio signal.

Dynamic EQ:

• Frequency-specific dynamic control: The dynamic EQ also works with the audio spectrum, but functions differently to multiband compression. It makes it possible to apply a boost or cut to certain frequency ranges based on their amplitude. As these are only limited to one EQ point, you can compress and expand at the same time.
• Threshold values and Q factors: The dynamic EQ uses a threshold value to determine when EQ adjustments should be made. If the input signal in a certain frequency band exceeds the threshold, EQ adjustments are made with a certain Q factor (bandwidth).
• Wide range of applications: Dynamic EQs are often used for tasks such as taming resonances, de-essing and fine-tuning tonal balance. It can be used to correct specific problems in audio material without affecting the overall dynamic range.

Key differences:

• Processing method: Multiband compression is primarily about controlling the dynamic range in different frequency bands through compression, while dynamic EQ is about making frequency-specific EQ adjustments based on the dynamic content.
• Frequency bandwidth: With multiband compression, the spectrum is divided into discrete bands, while dynamic EQ can be applied continuously to the entire spectrum.
• Applications: Multiband compression is usually used to influence the overall dynamics, while dynamic EQ is more versatile and is often used for precise sound shaping or to fix specific problems in the audio material.

To summarize, both multiband compression and dynamic EQ are valuable tools for audio processing, but they serve different purposes. Multiband compression is about controlling dynamics in specific frequency ranges, while dynamic EQ is about making frequency-specific adjustments based on dynamic content. The choice between the two depends on the specific audio processing requirements and the desired result.