Making sounds bigger by using compression to manipulate micro-dynamics

Compression is (sometimes) a complex and subtle process. Compression can be used to control macro-dynamics and micro-dynamics. What does this mean?

Roughly speaking, macro-dynamics refers to the volume differences between notes (for example, some notes might be louder than others). Micro-dynamics refers to the volume envelope – the differences in volume between different parts of the same note.

The traditional use of compression is to control macro-dynamics – to keep the performance consistent and even, and to help keep a track in its place in the mix. Think of a vocal performance where some syllables are louder than others, some sustained notes drop off early. Compression can be used to bring a more consistent level to the syllables and words so that they sound more even. It also makes it easier for the vocal to maintain its relationships with the other instruments in the mix – especially a busy or dense mix.

Compression can also be used to control micro-dynamics – the envelope of each individual note. This is most commonly done when using “character” compression on drums – the shape of each drum hit is being deliberately altered. This type of control can be used to make sounds bigger – by flattening a sound’s volume envelope, it has more power. Consider the envelope of a drum hit or piano – where the sound starts loud but rapidly decays. Compare this to the envelope of a trumpet or distorted guitar – where the sound stays at the same level for the length of the note. Even though both sounds might start at the same level and have the same duration, the sustained sound is louder and more powerful. Compression can be used to make the drum hit or the piano sound more like that – by either reducing the level of the attack or by increasing the level of the decay.

Practically speaking, this is usually done by using relatively fast attack and release times, coupled with a medium to high ratio and relatively deep threshold.

Just be careful – modern digital compressors can be very powerful, and even free plugins can be capable of completely flattening the sound. This can make a sound very loud and exciting on its own, but cause it to disappear in the context of the mix. This is because the articulation of the sound is greatly reduced (or removed!), so it becomes closer to pure tone. Even though it has more power, its psychoacoustic properties are closer to those of background sounds! This is why busy mixes tend to work better with dynamic, “spiky” sounds, but sparse mixes can be made to sound very full by using heavy compression.


    • fab
    • August 25th, 2010

    kim, your blog is an excellent source of advice and knowledge! thanky you very much for writing this.

    here is a question i have:
    whenever i try to compress piano (or rhodes) the way you describe, i get a lot of nasty pumping from the compressor reacting to the sustain portion. as i make the attack time longer, i get a “twack” type of sound.

    i really would like to make the sustain a little longer and possibly bring out the bell and tine sound of the rhodes a little more (apart from EQ that is).


    • fab
    • August 25th, 2010

    sorry, i meant to write: “i get a lot of nasty pumping from the compressor reacting to the ATTACK portion”

  1. @fab
    If your compressor is doing nasty things to your piano/rhodes track, I suggest you increase the release time. It’s probably way too fast – a piano/rhodes doesn’t need a super-fast release because the decay is quite slow (unlike drums, which can have a very fast decay!).


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