If you produce music, learning how to use compression isn’t optional. This is not a tool to embellish your tracks – it’s an effect that can drastically shape the vibe of a composition and bring to life a cohesive and professional mix.
I’ve been producing music, recording albums, and writing about music production for over 15 years, and during that time, I’ve seen compression used in countless ways – at different stages of production and across genres. Regardless of your skill level or budget, there are certain guidelines you can follow to get compression right and enhance the beauty of your mix.
In this article, I’ll break down what compression is, how it works, and when to use it to make your mixes sound professional.
What is compression in music?
Compression (also known as dynamic range compression or DRC) is a process that reduces the dynamic range of an audio signal. This means that when you apply it to a track, the difference between the loudest and softest parts becomes smaller, making quiet sounds louder and loud sounds quieter.
Here’s how the waveform of an uncompressed file looks like:
And here’s how the same file looks like when compressed:
As you can see, there are no more spikes on the waveform and it looks more cohesive. This means that the volume stays more or less the same throughout the song. So, how do you apply compression?
How compression works
First of all, any compressor, be it digital or analog, analyzes the input signal and applies gain reduction based on a set of parameters, which we’ll look into in a moment.
These parameters control when and how the compression kicks in; adjusting them so that every element of your mix is clearly audible is critical. These parameters are:
- Threshold: The level above which compression begins. In other words, compression will affect only the audio above this level.
- Ratio: It’s how you choose how much compression to apply. For instance, a 4:1 ratio means that for every 4 dB above the threshold, only 1 dB is output.
- Attack: How quickly the compressor responds once the signal exceeds the threshold. A slower attack leaves more transients passing through, whereas a faster attack will prevent clipping.
- Release: How long it takes for the compressor to stop compressing after the signal drops below the threshold.
- Knee: This controls how gradually or abruptly the compression is applied: a soft knee is gentle, while a hard knee is more abrupt.
- Makeup gain: We use this to boost the output after compression, because the signal is often reduced in volume.
Types of compressors
Every type of compressor features the same parameters we mentioned above. So, how are there differences between different compressors? The big difference lies in how they apply compression and the technology behind them.
Each type of compressor has its own character, or “soul,” which is why some are better for certain instruments or tasks than others.
Let’s take a look at the main types of compressors and what makes each one unique:
VCA compressors
VCA (voltage-controlled amplifier) compressors are standard because they offer clean, accurate, and versatile performance. They use electronic circuits to compress the signal, which makes them fast and reliable in any situation. Because of this, you’ll find them in most professional mixing consoles, and they’re great when you want tight control without adding much color to the sound.
Optical compressors
Optical compressors control the signal with sensors and lights. When the input gets louder, the light gets brighter and the sensor tells the compressor to reduce the volume. They offer a smooth and natural compression that works well with any acoustic instrument, from drums to acoustic guitars and beyond.
FET compressors
FET (field-effect transistor) compressors recreate the sound of tubes or valves using transistor circuits. They’re bright and fast, which is why they’re the standard in rock music. FET compressors can add both punch and color to a sound, which works magnificently with percussive sounds, guitars, or anything that needs to sound more aggressive and upfront.
Tube (or vari-mu) compressors
Unlike the other compressors that use vacuum tubes for amplification, variable mu compressors use these tubes as attenuators. As the amplitude of the input signal rises, the current directed to the vacuum tube’s grid decreases, and so does the compressor’s output level.
As the input signal grows, the compressor adapts its operation dynamically, which is the feature that makes variable mu compressors stand out. They add cohesiveness and richness to a track, and are ideal for drums but also for bus compression.
When and how to use compression
Compression can be used with any instrument or vocal track, but requires a different approach depending on the instruments’ characteristics and the result you aim for.
Below are a few recommended settings if you’re just getting started:
Drums
For kick and snare, you should try to preserve the punchy hits that push the rhythm forward. To do so, use a fast attack between 1-10 ms to let the first hit come through clearly, and a quick release to keep the energy flowing.
If you’re compressing the whole drum kit through the drum bus, try a slower attack (10-30 ms). A subtle ratio like 2:1 or 4:1 usually works well in this case.
Bass
Bass needs to be tight and steady in the mix, and keeping it under control throughout the song is one of those things most beginners get wrong.
A 4:1 to 6:1 ratio is a good starting point to control peaks without sacrificing the groove. Use a medium attack (10-20 ms) to keep the punch and a fast release (30-60 ms) so the notes don’t get choked. In my experience this keeps the bass strong and smooth, while leaving plenty of room for the other low frequencies in the mix.
Guitars, synths, and pads
These instruments usually don’t need heavy compression, so I’d suggest you use a subtle ratio like 2:1 or 3:1 to tame any sudden peaks and make it sit better with the mix, and then take it from there. When it comes to pads, a slow attack and release can create a pleasant effect that makes them feel immersive and warm.
Vocals
With vocals, a medium attack and release time with a ratio of roughly 3:1 – 4:1 is a good starting point. Make adjustments to your attack and release times until the vocals blend seamlessly with the other instruments, and use makeup gain consciously.
Compression techniques
Now that you know how compression works, it’s time to try three techniques that can take your mixing to the next level.
Parallel compression
With parallel compression, instead of compressing the sound directly, you make a copy of it, compress that copy heavily, and then mix it back in with the original.
This brings out more details and intensity in the sound while preserving the natural feel of audio. It’s often used for drums and vocals, but even in full mixes you can apply it to tighten things up.
Sidechain compression
Sidechain compression is common in electronic and dance music, but can be used in any genre.
This compression allows one sound to trigger the compressor on another, like making the bassline lower in volume every time the kick drum hits in EDM. This creates space in the low frequencies and gives the mix a rhythmic vibe.
You can also use it to make vocals stand out in a busy mix, as it can lower the volume of guitars or synths when the singer comes in.
Multiband compression
Multiband compression is slightly more complex, but offers a higher level of customization. Instead of compressing the entire sound the same way, you split it into different frequency ranges (lows, mids, and highs) and then compress each one separately.
It’s great if you need to sort out specific frequency clashes without drastically changing the nature of a mix or instrument.
Compression in mixing vs mastering
Compression is used in both mixing and mastering, but the way you apply it differs greatly depending on the stage of your production.
During mixing, you apply compression to individual tracks or instruments like vocals, drums, bass, and guitars, to make sure each one fits well in the mix. At this stage, compression acts as a tone-shaping and dynamic tool you use to make a vocal track more consistent, pump up the drums, tighten the bassline, or anything else.
The goal at this point is to give a sense of clarity and control, which means that this kind of compression is more “surgical” – you adjust the dynamics for each track, using different compressors and settings tailored to your needs.
Mastering, on the other hand, is all about the bigger picture. You’re dealing with the final stereo mix rather than individual instruments, so compression is applied more subtly.
Instead of fixing problems, here you use compression to enhance the overall feel of the track. A mastering compressor usually has a slower attack and gentler ratio, just enough to smooth out small peaks and help everything blend together. When done right, using compression when mastering will add a polished finish and a sense of cohesiveness to your piece.
Frequently asked questions
How does compression affect loudness?
Compression helps raise the overall level of a track by smoothing out the peaks, which in turn makes it sound louder even though the actual peak levels don’t change.
Can compression ruin my mix?
It very much will, unless you use it correctly! Over-compressing can make your mix sound flat, and under-compressing will make your song sound unprofessional. Finding the perfect balance to make your music shine is a critical step in the career of a music producer.
Is it better to compress before or after EQ?
There’s no right or wrong here. If you compress before EQ, the compressor responds to the raw signal. Compressing after EQ lets it react to a more polished sound. Try out both approaches and see which one works best for you.
What are the best DRC settings?
There aren’t one-size-fits-all solutions. Personally, I usually start with a standard 4:1 ratio and a -20 dB threshold, and then adjust based on what you’re working with and the effect you want to achieve.
How much compression is too much?
If you start hearing pumping or distortion, or if your track loses its punch, you probably overdid it.
Is a narrower dynamic range better?
A narrower dynamic range can help make a mix sound more consistent, but too much compression can strip away emotions. The secret is to find the right balance for the track you’re working on.
Is compression the same as limiting?
Limiting is a type of extreme compression that uses very high ratios, like 10:1 or higher. You use it to prevent clippings or to maximize loudness.
Should I compress every track in my mix?
Not necessarily. Only compress the tracks that you think need it. Some instruments or samples might already be well-balanced.
Do I need to compress during both mixing and mastering?
You might not need compression during mastering if your mix is already balanced, but a touch of mastering compression can help glue everything together even more.
Final thoughts
I hope this guide will help you use this powerful tool in the best way when working on your tracks. Remember that subtleness is always ideal, especially when you’re just getting started, so make sure you apply gentle compression first and see how that changes the sound signature of your instrument.
There’ll be a lot of trial and error, and there are countless compressors available these days, which makes it hard to pick one and master it. However, the good thing is that you can start with any compressor: even the one that came with your DAW is good enough to get started and make good music.
So, learn everything you can about the compression tools you have, and use them to take your tracks to the next level!
