AUDIO ENGINEERING BASICS (I’ll update this as time permits)
At the lowest level is noise. (the noise floor)
At the highest level is distortion
The distance between these two points, The noise floor and where distortion occurs is called the dynamic range. That is the window you have to work within while setting how loud or quite a signal is anywhere in your system while you’re mixing. This also applies to the final output of your mix.
Modern digital systems have a very wide dynamic range meaning they are very quiet with little noise and clipping (one form of distortion) only occurs after you pass 0db at the top of your meters.
Simply put, gain staging is the process of setting audio levels throughout a mixing chain. Making sure that levels are set properly and within the dynamic range throughout your mixing environment be it analog or digital. Audio equipment and plugins need to be run at a nominal levels meaning hot enough for them to work properly, to be high enough above the noise floor to minimize your ability to hear the noise, while avoiding distortion by not running the signal too hot and hitting the top of the dynamic range. Managing the audio levels through every aspect of your mix is an important consideration for a good mix and care should be taken to get it right.
Headroom is the term used for the space between your loudest peak signal and where distortion occurs. In other words how much room there is between the loudest signal and the top of the dynamic range.
There is an anomaly called True Peak where there isn’t enough data to actually represent the peak in your file or on your standard meters. When there is not enough data, while passing through the Digital to Analog conversion your D/A processor will try to create the missing signal that is actually above what you see on your meter. If you are running close to the top of the dynamic range it is possible to cause clipping in the converter and also in the analog domain. Give yourself a couple of db extra headroom to try to avoid running into problems when your digital information moves into the analog realm or during file compression for broadcast streaming.
LUFS stands for Loudness Units Full Scale and is a standard for metering that shows how loud your signal is. Good metering is essential in determining what your levels are actually doing.
Compressors look at the signal and turn down the loudest parts. When they start to turn down the signal is determined by the Threshold setting. When the signal passes the threshold, the compressor turns down the volume. How much it turns it down is the Ratio setting. How fast it begins turning it down is the attack setting and how fast or slowly it turns it back up is the release setting. You can use a compressor to smooth out a bass guitar that is played unevenly with loud parts and quite parts. There are many techniques for using compression. Using too much compression will remove the dynamics of a track or a mix and render it lifeless. Using a lot of compression can be an effect that is desirable but for the most part a little goes a long way.