Compression is the foundation to thicker, more controlled mixes.
But you can easily go overboard and make your instruments sound over-processed and flat.
Luckily, you have a fantastic solution: parallel compression.
In this complete guide, I’m going to teach you everything you need to know to use this powerful trick.
But first, make sure to download our FREE Parallel Compression Cheat Sheet.
It’s got all the best nuggets of wisdom from this article in one tight little package.
If you’re serious about using this technique in your mixes, you’ll want to keep this document saved on your desktop.
Grab it here:
- What is Parallel Compression?
- Parallel Compression Tips
- Trick #1: Keep the Vocals Up Front and Natural
- Trick #3: Add Some Life to Your Mix Buss
- Trick #4: The Secret of the “Rear Buss”
- Trick #5: Subtle Compression on Anything
- What Will You Try First?
What is Parallel Compression?
The key word here is ‘parallel’.
Rather than applying compression directly to an audio source, it’s the act of applying compression to a duplicate of that audio source.
Once the duplicate has been compressed, you mix it in with the original signal to the desired level.
This can create anything from more natural compression sounds to aggressive pumping – and everything in between. We’ll go over when to use this technique later in the article.
For now, let’s break this down into a step-by-step process, so you know how to set up parallel compression in any mix.
In most DAWs – including Ableton Live, Pro Tools, Logic Pro X, FL Studio 12, and Studio One – the easiest way is to first create a new aux/effect channel.
Then, send the audio from the channel that you want to compress with a post-fader send. This is the default send type for most DAWs. Set the send to 0dB.
Now you can add compression to the new aux/effect channel, and use the channel fader to blend it in. Simple as that.
Here are my recommended settings. You won’t stick to these exact settings, but they form a good starting point:
- Ratio: 3:1
- Threshold: As low as possible in most cases, with the compressor releasing towards the end of sustained notes. You’ll want 5-15dB’s of gain reduction, depending on how aggressive you want the sound to be.
- Attack Time: Fast for thickness (2ms or less), slow for punchiness (10ms or more)
- Release Time: Auto or slow (above 100ms) and timed to tempo of track
- Gain: Enough to bring the volume back up to roughly the same level
Parallel Compression Tips
Before you learn the best ways to apply this in a mix, there are a few important concepts to consider.
Tip 1 – Don’t Make the Compressed Version Louder.
If the new compressed channel is louder than the original source, it defeats the point.
You may as well just directly compress the original channel!
Tip 2 – Beware of Increased Volume.
Most of the time, blending in a duplicate channel will make the part seem louder – as you now have two channels for the same source.
As humans, we perceive an increase in volume as an increase in quality. Remember this at all times when mixing.
Now, because of this phenomenon, parallel processing isn’t easy to accurately evaluate. In most cases, you will also increase the volume of the source.
Just bear this in mind when you are deciding if you have actually made an improvement, or if you have just added volume.
Tip 3 – Be Conservative with Your Levels.
Considering the previous two tips, it’s best to be conservative with the level of the compressed duplicate channel.
Here’s how I recommend you set the level…
After creating the new aux/effect channel and applying compression, bring the channel fader all the way down.
Slowly bring the fader back up until you notice an increase in volume. When you do, stop and bring the volume back down a touch.
This should be the perfect level.
Now mute the new channel. Listen to how the sound changes.
Bring the new channel back in. Do this a few times and decide if you have made an improvement that is worth keeping.
Tip 4 – Turn On Plugin Delay Compensation.
This is an important tip for any mix where you start using sends.
Basically, it delays the playback of your entire session to compensate for the extra CPU usage.
In other words, it keeps your sends from sounding delayed from the original signal because of the software’s routing.
Many DAWs have this feature turned on by default. But sometimes you do have to go check the settings.
Google ‘[insert DAW here] plugin delay compensation’ and check.
Now let’s go over how to actually use parallel compression in your mixes.
Trick #1: Keep the Vocals Up Front and Natural
There are two ways to use this technique on vocals:
- Natural, subtle control to bring the vocals further forward
- Adding excitement and aggression
You can sit somewhere between the two, but these are the two approaches I find myself using the most.
To achieve subtle compression, start with the settings outlined above. Then bring up the level until it sits nicely under the vocal, just bringing it forward in the mix a touch.
For adding excitement and aggression, experiment with adding EQ or saturation to the parallel channel. Try boosting the top end with a high shelf, boosting the upper mids or adding heavy saturation (the Softube Saturation Knob is a great free saturation plugin).
When taking this second approach, it’s often better to make the new channel a bit louder to enhance the excitement. Of course, remember that this will also increase the overall volume of the vocal.
Trick #2: Give the Drums More Punch and Impact
Create a new stereo aux/effects channel and add a parallel compressor with the go-to settings.
Now use sends/busses to send each individual drum part to this new channel. This allows you to create a new drum mix for compression, rather than sending your entire kit there (for example, from the drum buss).
Generally, you want to send more of the kick, snare and toms than the overheads. Parallel kick compression can sound incredible.
Heavy parallel compression on the overheads can start to sound odd, and you will notice the compressor pumping as the cymbals ring out. Still, try sending a small amount of overhead.
Again, experiment with EQ on the parallel channel. Try adding heavy top end and low end boosts – or cuts to the mids. Just make sure you add a high-pass filter around 50Hz to stop the low end from getting out of control. Saturation also works well.
Trick #3: Add Some Life to Your Mix Buss
You can even use parallel compression on your entire mix.
When done well, this can add thickness and character to a mix. But it must be subtle.
Create a send from your mix buss to a new stereo aux. Start with the go-to settings outlined above, and use the same technique for setting the level.
Remember, you might just be making the track louder. So spend plenty of time muting and un-muting the parallel channel to check it’s making a genuine improvement.
For DAWs that don’t have the option to create sends from the mix buss, put a compressor with a “mix” knob at the end of the mix buss plugin chain. This knob changes the balance of the affected and unaffected signal. Just subtly increase the knob until it’s sounding the way you want.
If your compressor has the ability, try engaging the HPF so the lows are ignored (start around 100Hz).
Trick #4: The Secret of the “Rear Buss”
This is a slight variation of mix buss compression.
Instead of compressing the entire mix, create a new aux and send everything BUT the drum kit there.
Set all of the sends to 0dB, so you are getting an exact replica of your mix without the drum kit.
This time, a higher threshold might sound more musical. It’s up to you. You could also use a slower attack time.
As the drums are missing, the compressor will react more to the vocals, guitars and other melodic parts. This helps them to cut through at various points in the song (when they need it).
For example, when the vocals come in, everything (except the drums) will get compressed as the vocals trigger the compressor. But then when the vocal drops out, the compressor stops clamping down as much – because the vocal is generally the loudest part of a mix.
Trick #5: Subtle Compression on Anything
Subtle parallel compression doesn’t only work well on vocals or drums.
Sometimes, you might want to control the dynamics of a source without making it too obvious. It’s a great way to keep a sound natural while putting it “in the pocket.”
Plus, it just sounds different. Sometimes it works better than direct compression.
Just don’t forget to mix it in quietly. This technique works because it’s subtle, not because it’s in your face.
Get creative with it. Try it on guitars, backing vocals, voice overs, keys… anything!
What Will You Try First?
This is an incredibly versatile technique that many mix engineers heavily rely on. Some people perform the majority of their processing in parallel.
Apply what you have learned in this guide, but also don’t be afraid to try out new things. That’s how you develop your own style!
Just try to keep it subtle until you are confident in your decisions.
Before you go, make sure to grab our FREE Parallel Compression Cheat Sheet.
It’s got all of the best tidbits from this article tied up in one nice little package.
If you’re wanting to use the best parallel compression you can, this is a valuable tool.
Get it here:
Audio professional, musician and founder of Musician on a Mission.