Compression Before or After EQ?

It’s a commonly asked question: should you equalize before or after the compressor? Much of the online advice is “it depends”. I think we can give a better answer to aspiring mix engineers. What does EQ before compression versus after compression do for us?

EQ before compression affects the frequencies that the compressor acts on. This is important to remember because single band compressors tend to act on some frequencies more than others, especially low frequencies. Attenuating the the frequencies that we don’t want the compressor to process helps the compressor affect the desired frequencies more. But remember, unless you use a multiband compressor or set the compressor’s threshold so low that you start to get static compression (which undoes much of a compressor’s role), the compressor tends to flatten, or undo, the EQ curves that you send through it. Consequently, think of pre-compression EQ as your chance to tailor the frequencies you want the compressor to affect the most, but use post-compression EQ to do your detailed parametric filtering.

There are two ways to EQ before the compressor: using an actual EQ in the signal chain and filtering the compressor’s sidechain. On one hand, using an EQ in the signal chain changes the timbre of the sound we want to compress, but we typically have more filtering options than we get in a compressor’s sidechain EQ filter. On the other hand, using the sidechain’s EQ filter doesn’t affect the timbre of the sound we’re compressing, but we typically only get one band of filtering on the sidechain. Use a signal chain EQ to change a sound before compressing it. Use a sidechain EQ to only affect the frequencies a compressor uses for its compression algorithm, not to change the sound’s frequencies.

EQ after compression is useful when we want to alter a sound once we’ve compressed it. This is where we can fine-tune the sound we want in the mix, but be careful about boosting or cutting aggressively after the compressor because you can undo any balancing compression with dramatic EQ curves. Once you’ve put the sound in the dynamic range that fits it into your mix, with a compressor, use EQ to fine-tune where the sound fits into the mix’s frequency range.

Hopefully, this post helps clarify when to insert that EQ in your signal chain. There is always an element of experimentation in EQ and compression, but this house should help you determine when one method might be more helpful than another. If you need additional help filtering and compressing your mix, contact me. I can help.

Published by Greg Douras

I produce audio books and other audio projects. Let's bring your message to life! Get in touch, gregdouras.com.

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