EQ and compression are two processors that go hand in hand.

They’re like peanut butter and jelly, pizza and beer, burgers and fries....a bender and a hangover. 

However, because they treat the audio in such a different way, your sound may be different depending on whether you start by EQ’ing a signal, or add a compressor to it first.

This relationship has been around forever and ever since the start the industry has been asking itself the same question:

“EQ before compression or compression before EQ?“

It’s a never-ending debate of preference that doesn’t have a right answer, but there are some general guidelines you can take into consideration.

Two Simple Tips to Guide you Through

• EQ before compression if you need to compress drastically – If you don’t need to EQ that much, but you need to compress a lot, then insert your EQ before the compressor. However, it’s usually a good idea to do any filtering you need to do before you add compression.
• Compression before EQ if you need to EQ heavily – This is the opposite. If you really need to EQ your instrument to make it sound better, then insert the compressor before the EQ.

Why?

If you insert the EQ before the compressor the compressor will compress your EQ fixes more than the rest of the signal.

Think about it. You’re boosting certain frequencies to make them louder, and then you go ahead and compress them down again. Seems redundant, doesn’t it?

Therefore, if you want your EQs to make a bigger impact, inserting them after the compressor makes more sense. At that point, you’ve already compressed the signal so the EQ isn’t affected.

Double-Whammy Processing

Another trick you could try is to chain two EQs and two compressors together.

Repair First With the First EQ

If there are obvious frequency problems in your signal that you want to get rid of then put an EQ before the compressor. Use the first EQ only for cuts and repairs. Use your filters to take out any unnecessary low or high-end and cut out any annoying frequencies.

If there’s low rumble you filter it out.

If there’s obvious muddiness then you cut that in the 200ish Hz area. If you’re mixing a kick drum and it sounds like it’s inside a cardboard box then set your attenuators to stun around 300 - 600 Hz.

In that case, the reason you don’t want to put a compressor before is that you don’t want the compressor to accent those annoying frequencies you’re going to EQ out anyway. It’s unnecessary work on the compressor’s part.

Tame the Peaks With the First Compressor

Insert this compressor after the EQ and only use it to tame the peaks. Just have it compress lightly, with a dB or two of gain reduction.

Flatter Your Frequencies With the Second EQ

Adding a second EQ after your compressor allows you to add boosts to the frequencies that you want to bring out in the mix without the compressor fighting those boosts. Think of this EQ as makeup. Whereas your first EQ was reconstructive surgery, this one really makes your signal shine. Do all of your boosts here to make your signal really stand out.

If you had also boosted during the “repair” phase then the compressor would have pushed down those frequencies even harder because an EQ boost is essentially just a frequency-specific volume boost.

With a louder volume in those frequencies and the compression threshold staying the same, the compressor would react even harder to compress those boosts.

Add Character With the Second Compressor

If you need to compress heavily to bring out all the little intricacies and nuances of your signal do it here. If you want to add punch to your drums, or need an extra in-your-face sound to your vocals, use some heavy-handed compression here.

Adapt as Needed

If you feel like the second compressor is clamping down on the frequency boosts you did in the second step you can do one of these things:

• Add a third EQ to bring those frequencies back again. You can use the opportunity to use a different style of EQ, like a Neve or Pultec emulation to give character, similar to how you use the second compressor.
• Move the character compressor before the previous EQ so the compressor that’s taming the peaks and the character compressor are working in series.
• Use parallel compression instead to add character and skip the second compressor after the first EQ altogether.
• Use a multi-band compressor to avoid compressing the frequencies you are accenting with the second EQ.

If you have plug-ins that eat up a lot of your CPU power, you can use the native EQ and compressor for the first round. After that, you can switch to better sounding plug-ins for the make-up.

EQ and Compression at Different Stages of the Production Process

Depending on whether you’re recording, mixing, or mastering, this argument has a few different sides.

During Recording

When you’re tracking instruments, use your microphone as the EQ. The frequency response changes as you move the mic.

It’s like tweaking knobs without the knobs. And if you have access to an outboard, on-the-way-in compressor, by all means, use it if you want.

During Mixing

This is going to be the big “it depends” answer. If you don’t need to EQ that much, but you need to compress a lot, then insert your EQ before the compressor.

Or, if you really need to EQ your instrument to make it sound better, then insert the compressor before the EQ.

But you will see all kinds. Compression before and after, as well as in parallel.

During Mastering

In mastering, I recommend that you EQ and filter first. I compressed first for a long time, but I was shown the error of my ways. However, I would add that when I mix I tend to add mix bus processing so there’s always some compression - although subtle - going on before the mix gets mastered.

The thing is, when you’re mastering, EQ is THE MOST IMPORTANT processor. You want the song to sound great frequency-wise before you start compressing it.

A compressor before might skew your perception, making you EQ differently than you should.

So depending on which part of the audio production process you’re on, the approach to EQ and compression becomes different.

There's No Right Answer - But Now You Have a Plan

As you can see, there's no real answer that's correct. Mixing is an art and it's subjective to how you want things to sound. Hopefully, you'll still feel a little more comfortable knowing how they interact with each other after reading this post.

We've been talking about EQ a lot already this week and there's more to come tomorrow as I'm making a Wacky Wednesday announcement that you're gonna love if you want to start making cleaner mixes that don't sound muddy in the low-end.

If you want to improve your EQ skills, make sure to keep an eye on your inbox tomorrow.

Talk soon!

Björgvin