Upward Compression: The Overlooked Mix Hack You’ve Been Missing
Understand the advanced sides of dynamics processing, how these upward and downward processes work, and how they can help your music.
You’ve heard of “compression”, it’s how we reduce the dynamic range of a signal when certain peaks get too loud. You may also know about expansion or gating, which reduces the volume when signal gets too quiet.
But what if we started calling these processes downward compression and downward expansion? This simple shift in terminology hints at the idea that there are opposite processes, ones that can also change a signal’s dynamic range but in a different way.
In this article, we’ll explain what might be new concepts to you – upward compression and upward expansion. In addition, we’ll suggest some cool areas it can be applied in music production. This may be a slightly different way to think about dynamics, but wrapping your head around these concepts is well worth the effort.
Want to bring out the softer details of your drums or a subtle, easy-to-miss part of a vocal take? You may very well benefit from upwards compression. Maybe you want to dabble with some upwards expansion to get a slight transient boost to restore much needed dynamic range in a recording? Read on to learn how.
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Downward Compression – Needs Very Little Explaining
You know all about traditional compression. Just incase you need to be brought up to speed on what a compressor does to sound, watch the video below.
In this article, we’ll refer to this type of compressor as “Downward Compression” because it reduces the volume of a signal’s peak after exceeding a set threshold.
Let’s turn the concept on its head now…
Upward Compression – The Same But Different
Flipped upside down, upwards compression is still compression – that is, it still results in the dynamic range of the signal being reduced, but this squeeze happens from the other side: it turns up lower-level signals, closing the gap between the noise floor and the signal’s average level.
Existing owners and Waves Ultimate subscribers can get upward compression from our very popular plugin MV2. When using it on a track, you set two points of gain compression: High Level sets the amount of downward compression (classical compression) bringing loud sounds down, whereas Low Level sets the amount of upward compression pushing quiet sounds up. If both dials are set, the signal is squeezed in both directions!
What is Upward Compression Used For?
Upward compression is great for bringing out details in a sound such as room sound or reverb effects heard in gaps of a recording. These softer moments can be boosted by increasing gain as the lower level signals falls below a threshold. This technique can help you to bring out nuanced details such as gentle ghost notes in drum performances, subtle breath-like qualities in vocal recordings or finger articulations in guitar takes.
One advantage of upward compression is that it reduces dynamic range without processing transients. Standard ‘downward’ compression is able to increase your average level in the same way, but when squashing from high to low, you have to be careful about ruining those very early parts of a peak - being the transient information.
Can Upwards Compression Go Too Far?
Yes, it can. Since upward compression works by increasing the gain of quieter signals, there must be limits in place to prevent it from being over-baked. For example, a signal at -68dB doesn’t typically need to be boosted all the way to 0dB. To avoid this, most tools offering upward compression include a ceiling or range setting, or have such limits built into their design.
Is Upward Compression Like Downward Compression with Makeup Gain?
Put simply, yes. Upward compression techniques will often have equivalent effects to downward compression with makeup gain added. However, it’s the edge cases where the effects will be different, and it’s for these edge cases that you should know exactly how each works and how to use them.
How to Set Up Upward Compression in Waves F6
F6’s dynamic bands are activated by dialling in Threshold and Range parameters, so with the right combination of these and a band’s gain control, it can perform downward or upward compression or expansion.
To activate a band in F6 as an upward compressor, reduce the Threshold control and increase the Range above zero. The band should start increasing when its signal crosses this low Threshold. You can define the band’s width using its Q, and don’t forget to time its Attack and Release controls.
Downward Expansion and Gating
If we have multiple types of dynamics, then we’ll need to talk about expansion as well as compression. Traditional expansion works in the opposite way to compression: if a signal’s level falls below the threshold, it’s turned down even lower, causing a bigger rift between the highest and lowest average levels in a track.
The most common use of this type of expansion is in gating. Gating is often applied to eliminate low-level drum spill picked up by microphones when the main drum shell isn’t playing, or to remove background buzz noise from a guitar amp when the guitar isn’t being played. That’s the essence of gating.
You’ll also find downward expansion used in applications like trance gating, which can have its edge taken off by applying less reduction, so the signal reduces in level rhythmically rather than cutting out rhythmically. But “Trance Expansion” doesn’t have as nice a ring to it.
In mixing, expansion is useful not only for cleaning up spill on drum recordings but also for shaping the impact of transients in room mics or reverb effects. With carefully chosen timing, expansion can subtly soften the feel of certain tracks without abruptly cutting off the signal.
What About Upward Expansion?
The fourth type of dynamics processing in our quartet is upward expansion. In theory, this involves amplifying parts of an audio signal that exceed a set threshold—for instance, boosting only the transient peaks. Achieving a similar effect with traditional downward compression would require using slow attack and release times to compress the signal after the transient, followed by applying makeup gain. However, there's another, more conventional way to achieve upward expansion that you might not have considered.
Transient Shaping Can be Upward Expansion
By using a plugin like Smack Attack to increase transients while our signal’s Sustain level remains unchanged, we’ve applied a sort of upward expansion process.
Upward Expansion for Restoration
One other use of upward expansion is in restoring audio that’s either been corrupted, recorded at low quality, or perhaps has been mastered too heavily. A process of increasing peaks requires care, but as long as the signal hasn’t been strictly clipped or limited so that information is lost, this is one potential application of upward expansion.
Try These For Yourself
Reading about how compression and dynamics processors work in audio can only take you so far. Now that you have a basic understanding of upward compression, it’s time to try it out. Download a trial of MV2 and apply it to a track with subtle details you’d like to enhance. Raise the Low-Level fader and notice how it brings those details forward, giving your track a fuller, more rounded feel.
Next, try using a dynamic EQ plugin on a track with lots of detail, like a beat. Instead of standard EQ adjustments, create an upward dynamic band around the kick range. Listen to how it strengthens the groove without overpowering the other elements of the drum kit.
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