How To Use Parallel Compression Like A Pro (+ 5 Powerful Tips)

Wondering what parallel compression is, and how you can use it to make your home studio mixes sound more professional?

You’re in the right place.

In this article, you’ll learn everything you need to know about parallel compression.

We’ll start by talking about what it is. Then, we’ll talk about how you can use it. And finally, we’ll wrap up with 5 powerful tips that will help you make the most of parallel compression in your mixing process.

But before we dive in, make sure you grab my free compression cheatsheet below. It’s packed with additional tips and tricks that will help you approach compression with more clarity and confidence right away.

Download my FREE Compression Cheatsheet

What Is Parallel Compression?

Let’s say you want to compress a track in your DAW.

Normally, you’d scroll over to this track, click on an empty insert slot, and add a compressor plugin directly onto the track.

This is called “serial” compression, because the compressor is placed in series, or directly in line, with the track itself.

This is the normal way to apply compression, and it works pretty well most of the time.

Parallel compression is a bit different. Instead of applying a compressor directly onto a track, we make a copy of that track and apply the compressor to the copy instead. Then, we blend in this compressed copy underneath the original, uncompressed track.

Now we have two versions of the track playing together — one with compression and one without it. The track with compression is playing “in parallel” with the original, hence the name parallel compression.

When Should I Use Parallel Compression?

In most cases, serial compression works fine. But adding a compressor directly onto a track can often significantly change the way that track sounds. Sometimes this is what you want. But sometimes, the track already sounds great, and you just want to subtly enhance it.

In this case, I find parallel compression to be much more useful. Since it usually sounds more transparent and natural than serial compression, it can enhance a track without dramatically changing the way the track sounds.

In short, whenever I like the way a track sounds but I just want to enhance it a bit, parallel compression is often a great solution. Otherwise, serial compression is my go-to choice.

Now that you know when to use parallel compression, let’s talk about how to use it in some common mixing scenarios.

How To Use Parallel Compression On Vocals

Some vocal tracks are wildly dynamic. There’s a huge difference in level between the softest and loudest parts of the performance.

With tracks like these, it’s often impossible to find a static fader position that works throughout the song. If you set the track’s fader to the correct level in the verse, the vocal often gets way too loud in the chorus. If you set the right fader level in the chorus, the vocal sounds too quiet in the verses.

For vocal tracks like these, serial compression is usually the best solution.

But sometimes, the vocal is already sitting evenly in the mix. You can hear most of the words clearly, and there aren’t dramatic swings in level on the voice. All you’re missing is a bit of the low-level detail. When the vocalist trails off at the end of a phrase or dips into a lower register, the voice drops in volume and you lose these quieter parts in the mix.

Parallel compression can help bring up this low-level detail, so you can hear all the subtle nuances that bring the vocal to life. Here’s how to pull this off…

First, create a new aux track in your DAW and place it next to the vocal track.

Set the input of this aux track to an unused bus.

Add a send on the vocal track. Set the output of this send to the bus you used on the input of the aux track.

Turn the send’s volume up to zero and click the pre-fader button.

When the pre-fader button is engaged, the level of the send won’t be affected by the fader position of the track. This way, you can turn the vocal up or down in the mix, but the sound of the parallel compression will remain consistent.

Add a compressor plugin onto the aux track. Use the following settings as a starting point:

  • High ratio (anywhere from 4:1 to 10:1 usually works)
  • Medium attack time (~ 5 ms)
  • Fast release (I usually set this as fast as possible)

Turn down the threshold until the vocal sounds slightly overcompressed. When applying parallel compression, you usually want to overdo it, since this track will be blended in with the original.

Once things sound good, turn up the compressor’s makeup gain until there’s no change in level when you flip the compressor in and out of bypass.

Finally, with all the tracks in your mix playing, adjust the level of the aux track until the vocal sounds balanced and natural in the mix. You may have to turn down the original vocal track to compensate for the increased volume the parallel compression adds.

You can now think of this aux track as a low-level detail fader for the vocal. If you’re missing the quieter parts of the vocal, just turn the aux track up.

How To Use Parallel Compression On Drums

Parallel compression can add punch, energy, and density to drums. Used correctly, it can make your drum tracks sound larger than life.

When you’re applying parallel compression to drums, there are three different approaches you can use. The approach you’ll need depends on what you want to add to your drums.

First, listen to your dry drum tracks and ask yourself — what are these drums missing? Choose one of the three options below.

  1. The drums are missing punch. You want to hear more “thwack” on the front-end of the kick and snare.
  2. The drums are missing sustain. You want to hear more of the decay and ring of the drums.
  3. The drums are missing both punch and sustain.

Parallel compression can address each of the problems above. The settings you’ll need to use, however, vary widely depending on which problem you’re trying to address. That’s why it’s essential to figure out what you want to add to your drums first.

Once you’ve decided which of these three approaches you’re going for, you can apply parallel compression with clarity and confidence.

Your next step is to get started. I put together a simple video that shows you the three different ways to apply parallel compression to drums. You can watch it below:

5 Powerful Tips For Making The Most Of Parallel Compression

You should now be starting to wrap your head around parallel compression. But there are a few things worth keeping in mind if you want to avoid the major parallel compression pitfalls and approach the process like a pro. In this next section, we’ll be exploring five of these things. You can read about them below or watch a video that covers three of them here:

Tip #1: Beware Of Volume Changes

When you add parallel compression via a send (the process outlined above), there’s one major pitfall you need to watch out for.

As you’re blending in the parallel compression, the sound of the track will get louder.

Here’s the problem: louder ALWAYS sounds better to our ears. So when you’re applying parallel compression, you can often be fooled into thinking you’re making things sound better. In reality, you may just be turning them up. And sometimes, you might even be making things worse.

You have to be careful of this when applying parallel compression.

The best way to avoid this pitfall is to do an A/B comparison every time you apply parallel compression.

To do this, first duplicate the track you’re applying parallel compression to. Now you should have three tracks in your session — two without compression and an aux track with a compressor on it.

Mute one of the uncompressed tracks as well as the aux track. Listen to the original sound with no parallel compression.

Then mute this uncompressed track and unmute the other two tracks. Adjust the volume of these two tracks until there is no difference in level when you flip back and forth between this group and the original uncompressed track.

Now you can flip back and forth between these two versions of the sound and decide which you prefer. Do this, and you’ll be much more likely to make good parallel compression decisions.

Tip #2: Use Delay Compensation

It takes your computer a few milliseconds to process sound through a compressor plugin. Normally, this delay is negligible. But when you’re using parallel compression, you need to pay attention to it.

If you have two versions of a track playing in parallel — one without compression and one with it — the compressed version of the sound will play back a few milliseconds later. When the two versions of the sound combine, they will play at slightly different times. This can create something called comb filtering, which sounds terrible and is definitely not what you want.

The solution is to turn on delay compensation in your DAW. This feature will correct these timing differences, so all the tracks in your session play perfectly in sync.

You absolutely need to make sure this feature is turned on when you’re using parallel compression. In most DAWs, delay compensation is enabled by default, but it’s worth checking just to make sure.

Here are a few links that will show you where to find this setting in your DAW:

Tip #3: Avoid Holy Grail Thinking

Whenever we discover a new mixing technique, we tend to overvalue it. We think it’s the “holy grail” that will make our mixes sound incredible. We use it all the time and on everything. And usually, our mixes end up sounding worse, not better, because of it.

Parallel compression is certainly useful. But it has its place, just like everything else. It can make a positive difference when used appropriately. But it’s not going to turn a crappy mix into a great one.

I find parallel compression works well on acoustic drums. Beyond that, I only use it occasionally. Some mixers prefer to use parallel compression more often — that’s just me.

Tip #4: Add It On A Send

There are two ways to apply parallel compression.

Some compressor plugins have a “mix” knob. You can use this knob to blend the uncompressed sound with the compressed sound. Aka, instant parallel compression.

The other way to apply parallel compression is by adding it to an aux track, as described in this article.

I prefer the aux track approach for several reasons.

First, it gives me a greater degree of control over the volume of both the dry and compressed tracks. I have a separate fader to control each, which gives me more flexibility in the mixing process.

The other reason I prefer this approach is because it allows me to send a different balance into the compressor than I’m using in the main mix.

If I add a compressor across my drums and use the mix knob to apply parallel compression, I don’t have separate control over the level of the kick being sent into that compressor. But if I apply parallel compression using an aux track, I can set up sends to that compressor on each individual drum track. This way, I can turn down the level of the kick being sent into the compressor without affecting the level of the kick in my mix.

When I add lots of compression to drums, the kick often comes up in volume. This aux track approach helps me achieve a more balanced parallel compression sound by turning down the kick in the compressed track without turning it down in my mix.

Tip #5: Less Is More

Parallel compression is like salt. A little bit can add flavor, but too much can ruin a dish.

Less is more. Too much parallel compression can make a track sound flat, one-dimensional, and fatiguing.

When in doubt, step away from your mix for a few minutes. When you come back, play the track and ask yourself — does this sound too aggressive? Listen for negative artifacts like distortion and edginess. If you’re hearing these things, you’re probably using too much parallel compression.

Wrapping Things Up

You should now know how to approach parallel compression with clarity and confidence in your mixing process.

If you’re ready to dive deeper, don’t forget to download my free compression cheatsheet, which is packed with more tips and tricks that will help you approach compression like a pro. You can download this cheatsheet for free here:

Download my FREE Compression Cheatsheet

Before you go, leave a comment below and let me know…

What’s your go-to plugin for parallel compression?

Happy mixing!

About Jason Moss

Jason is an LA-based mixer and the founder of Behind The Speakers. He's a graduate of New York University's Clive Davis Institute of Recorded Music. His how-to articles have been featured in leading industry publications by Berklee, TuneCore, SonicScoop, The Pro Audio Files, and Disc Makers.