Compression of music

What is compression?

Compression is an effect you can put on an instrument, a sample, a group, or even the master, depending on your DAW.

What does it do?

In simple it lowers the volume differences or jumps in the input signal. If you compress a piano the compressor will lower the volume of the loud notes and higher the volume of the faint notes.

Why should I compress?

That is an interesting question. Compression is a useful tool when it comes to mastering. If you want your song to sound well you will have to compress some instruments. Compression makes your mix clipping less often, so you will be able to raise the global gain higher. The instrument you compress will be heard better in the song. It will be more assertive. If you compress drums they will be less hard and accurate but more punchy. Additionally it makes your song sound more natural and professional if you know what I mean :-) 

Things you should compress:
- drums, especially kick and snare ( particularly in Dubstep and Hardstyle )
- Fx like noise ( but just a bit )
- Hardstyle kicks
- vocals ( just a bit )
- master ( just a litttttttttle littttttttle bit and very sensetive )

Obviously compression always decreases the dynamic of your mix, so please do not exaggerate. :-) 

Things you should not compress:
- Piano!!! :-) :-) :-)
- other Keys
- most Synths ( often the plugin has a build in compressor )
- violins and so
- guitar ( OK maybe a bit )
- everything other...

How to compress:

Most DAWs have a build in compressor, which absolutely reaches our needs.

Standard compressors have the following adjusting options:

- Threshold: The input signal level from which the compressor starts working (often from -30 to 0 dB, std: -10 )

- Amount: The amount :-) the input signal is lowered, if it exceeds the threshold. ( std: 75% or 1\2 )

- Knee: The linearity of compression. Prevents that the compressor hits directly with the full amount. Makes the compression smoother.

- Attack: The time between the transgression of the threshold and the start of compression. ( Big attack causes short impulses to "slip" through the compressor )

- Release: Time between the level falls under the threshold and the end of compression. ( Causes the compression to be more smooth )

For most purposes the standard settings are OK. However I recommend to play around with them. For example you will need a lower attack for short samples like drums and a lower amount and higher threshold for vocals and noise.