Compressors, Limiters, Gates and Expanders Basics

Compressors, Limiters, Gates and Expanders Basics

Today we are going to cover VGA’s such as compressors, limiters, gates and expanders.

When I first looked at plugins I was confused, and had no clue what they did, and how to use them. If this is you it is ok keep reading and applying and it will become easy.

In the next few posts we will be going over audio signal processing, and how they all work together.

Today’s post will be a little more like a lecture with some homework at the end to get you started.

It is important to understand the basics of VGAs as they can help your mix if used right and hurt if not destroy a mix if used wrong.

Before we get started it is important to know what dynamic range is along with timbre.

Dynamic range is: “the difference between the quietest and loudest volume of the given audio”

Timbre is “what makes a particular musical sound different from each other”

A bass guitar and guitar can be playing the same note in the same key and the same pitch but each have its own characteristic that makes it possible to identify which is a bass and another a guitar. The same scenario will apply with any two instruments.

So What are VGAs (Variable Gain Amplifiers) and Why You Must Care

VGA is used to automatically control the dynamic range of a sound source.

An example of this would be a compressor will decrease the overall dynamic range and a limiter will only allow the sound to play to a specific amplitude and then it will cut the sound source off limiting its dynamic range

They can tailor the envelope of a sound source and eliminated noise from a sound source. They can also prevent a circuit overload when recording

VGA Side Notes

• If you record with a VGA going on you are STUCK with it whatever it is”
• Any use of a VGA changes the Timbre and colorize the sound source.
• If you are not 100% committed do not record with the VGA on the source material. You can always go back and apply it with the original while mixing.

4 Types of VGA’s

Audio Compressor – Reduces the dynamic range of the source material

Audio Limiter – A dramatic form of compression

Audio Expander – Increase the dynamic range of a source material

Noise Gate – A dramatic form of expansion

VGAs are almost always inserted into the signal path, they are seldom used as a global effect applied to auxiliary sends, and proper application of VGAs during mix down is critical in creating a professional mix!

VGA Parameter Controls

Threshold – Determines AT WHAT LEVEL the VGA starts processing. (When do you go to work)

On an expander/gate, it determines how loud a signal must be before it can be heard (passes through the gate)

On a compressor/limiter, it determines at what level you start reducing the dynamic range

Ratio - Determines THE DEGREE to which the VGA does its job ( How hard does it work?)

On an expander/gate, it determines how much it will turn down the signal once it falls BELOW the threshold.

Attack - How quickly to start working

On a compressor / limiter once sound reaches threshold the attack will determine how fast the compressor starts to reduce the dynamic range.

On a Noise gate/expander once the signal reaches threshold it will determine how fast sound will be allowed to pass through the noise gate.

Release - how fast after dropping below the threshold the VGA stops working

On a compressor it will determine how fast the compressor stops working once the signal drops below threshold

On a noise gate it will determine how fast the gate closes and no longer allows signal through once it falls below threshold.

VGA Parameter simplified

Threshold: When do you go to work?

Ratio: Once at work how hard do you work?

Attack: How quickly do you start working once work has started

Release: How quickly do you stop working once work has stopped.

To get an idea of what I am talking about I would highly suggest checking out this page which has a TON of sessions you can use to experiment with.

Download one of the free multi tracks and instantiate a plug in your signal chain and start using some of the VGA’s that your music production software comes with.

Adjust the parameters that were talked about here so you can get a better feel for what each one does.

Look for a video from our YouTube channel showing the parameters very soon!