29 mai 2014 ~ 0 Commentaires

Coursera – Music Production Week4 – Demonstrate how to use a specific compression plugin

Hello ! This week i’ll demonstrate how to use a specific compression plugin: Ableton Live’s built in compressor and his parameters including threshold, ratio, attack, and release.

We will look also at what visuals the device has.

Ableton live’s 9 built in compressor:

What’s the purpose of a compressor ?

A compressor is used to reduce the dynamic range of an audio signal. It will decrease loud sounds and increase quiet sounds.

In order to do that the compressor need to listen the incoming signal and be configured to reduce the dynamic in the way we want.


Threshold:



The Threshold is the level at which the compressor will start to be active.


When the input sound (in green) is above the threshold (-10dBFS here) it can be compressed (based on other parameters that we will see after)





Ratio

The ratio is the compression level. Values are displayed INPUT:OUTPUT.

In this case we have 4:1, which means that when the audio signal is above the threshold, for 4 DBFS input we will have a 1 DBFS output.



Attack:

The attack is the amount of time, when the input sound goes above the threshold, before the compressor effect will be fully effective.

In this case the attack is configured to 2ms, so when the input sound goes above the threshold, from 0ms to 2ms the compressing effect is rising progressively.



Release:

The release is the amount of time, when the input sound goes under the threshold, before the compressor effect will be fully inactive.

In this case the attack is configured to 50ms, so when the input sound goes under the threshold, from 0ms to 50ms the compressing effect is diminishing progressively.



Others parameters:



Knee level:

The Knee level is a way to soften the compression ration at the threshold point.
When we are configuring the compressor to have a compression ratio of 4:1, just before the treshold the compression ratio is 1:1 (no compression) and just after the treshold, without a knee, it’s 4:1.

With a knee we can have at the treshold point a smooth curve from 1:1 to 4:1 compression ratio. The lenght of the curve is determined by the knee level.



Lookahead:
The lookahead is a value in ms, which can be used to allow the compressor to look at the input sound envelope in advance.

A higher value makes the compressor sound more natural but it induce latency.

Visualization:

This compressor has 3 visualisations configuration:





1. On this visualization we can see the threshold, gain reduction and the output level.

This is the minimalist view available.






2. On this visualization we can see the threshold, gain reduction, the output level and the compression curve.

The empty circle is the treshold level and the plain circle is the input level.

This is a great view to understand how the compressor is configured and how he reacts at a given moment.



3. This visualization represent the input sound and the compression effect over time.

The greyed sound wave is the input sound.

The orange line is the treshold

The yellow line is the compression effect applied on the sound.

This is great to look at how the threshold is configured in comparison to the input signal over time.

This is also great to look at the compression effect over time.

This is in my opignon the most useful view.



Well I think you know now how to use in detail this compressor !
Thanks for reading !