Compression is one of the most important plugins to master. It helps you adjust the correct amount of depth in your tracks, soften peaks, and levels the dynamics of your audio.
First, there are a couple types of compression you should know about:
Basic Compression - General compression limits the dynamic range in a track. The dynamic range is the distance between the loudest (highest dynamic) peak in the track and the quietest (lowest dynamic) peak in the track.
Multiband - Same as basic compression, but the option to affect specific frequencies of the track similar to EQ.
Parallel - Keeps more of the original sound of the track by running the original audio alongside compressed audio. Most compressors have the option to run in to parallel by using the mix setting.
Serial - Multiple compressors in line on same track. Also helps keep the natural, original sound because you compress in stages as opposed to one single compressor doing all the work.
Next, here are most of the options or settings your compressor may have:
Ratio - The ratio at which the audio is compressed.
Attack - How quickly the compression is triggered when audio reaches threshold.
Release - How quickly the compression stops when audio drops below threshold.
Sensitivity/Threshold/Compress - Sets the level to engage compression.
Makeup - Adding compression naturally quiets the track. Makeup helps get back the lost loudness. A good starting point is to add as much makeup as gain reduction took away. Not always easy to see on all compressor plugins but having a general idea is still a good place to start.
Mix or Dry/Wet - Usually in %, let’s you know the percentage of dry (uncompressed audio) and wet (compressed audio) coming out of the plugin. This is where you can turn a standard compressor to a parallel compressor.
Knee - How gradual the ratio is applied to the compression. A higher dB knee makes a softer knee, lower dB gives harder knee. If you have this option a softer knee is typically best.
Difference between Peak and RMS:
Root Mean Square - average of the sound signal
Peak - loudest signal
In general, if you’re looking to get rid of harsh S’s or some extreme peaks obviously that’s where a peak based compression could suit best. If you don’t have sharp dynamic changes in the song, changing to RMS could be beneficial.
-If needed, heavier compression is typically best suited early on individual tracks.
-For a more natural sound, use parallel compressors with the serial method. But be cautious as multiple compressors can do far more harm than good if used too aggressively.
-Very mild compression on the master to glue it all together and make the entire track cohesive dynamically.
-Less is more!
What is a limiter?
One of the most commonly used tools in any audio production are limiters. These plugins help level audio and will catch any eardrum shattering peaks in the mix.
If you are not getting the desired result or you are using it for the first time, start with these 2 general rules when applying a limiter to your track:
-Only one is used on the master track.
-A high threshold that triggers the limiter only at the loudest peaks.
If you follow those 2 main rules, using a limiter should be simple and effective.
below is a guide of what each potential knob or setting
Gain: The input. 'Volume' controls the output after a device or plugin, and 'gain' controls the input.
Ceiling: The max output level. If you do not get the option to set the ceiling, most limiters are automatically set to -0.3 dB. This is because while the limiter is attempting to flatten the sound at exactly what you set your ceiling to, some sound still squeaks through and can become distorted. So if you do have the option to control your ceiling, make sure you are not pushing it all the way to 0 dB. Give it a little headroom.
Threshold: The level at which the limiter is triggered to engage. High is typically best.
ISP: Inter-Sample Peak detection detects peaks in the actual sample of that extra audio that sneaks through. Not necessary when editing podcasts as you typically do not need to cram as much loudness in a track as possible without it distorting. Although, having it on will certainly not hurt anything.
Release: How long the limiter is engaged. Usually you want a pretty quick release time, sometimes immediate. Improper use can lead to pumping, pulsating effect that is not pleasing to listen to. If you have the option for auto, it may be in your best interest to use it. Otherwise, opt for a short release time.
Lookahead: How far in advance your limiter is looking to catch peaks. Having too far lookahead time can muffle sound, but you definitely need some time to prevent clipping. 1-3 ms is usually plenty on this dial.
L/R: Each channel is limited independently as opposed to stereo that limiting applies to both when either hits the cut off. L/R makes a louder overall signal but can lead to more chances for clipping and changes the shape of the track and effects panning. As with other components to limiters, this is not something you are likely to need with podcast editing.