Compression, EQ, and Gates are essential to creating an enjoyable, clear sound. These effects all work together and can help to add clarity and balance to your mix.
Compression can be a tough concept to wrap your head around but having a better understanding of the pieces that make up compression can help the effect make more sense. In an audio waveform, we have high and low points (loud and soft) and compression can help us to reduce the gap between those. I often hear that compression makes your loud parts quieter and quiet parts louder which isn’t entirely true. Compression works by just lowering, or compressing, the loud signals therefore allowing us to push our level as a whole which gives the illusion that we have increased the quiet parts. We do this by defining the loudest peak in the signal and placing our threshold just below that point. By doing this, any amount of audio that goes over that defined level will be adjusted by the compressor and will be reduced. We define the amount of reduction happening with our ratio. The ratio is represented as decibels of input to decibels of output. For example, in a 2:1 ratio, with our threshold set at -30 decibels (dB), if our signal goes to -20dB (or 10 dB over our threshold), the compressor will reduce it and output that as -25dB. We can control the speed at which compression kicks in by using our attack (how quickly the compression happens) and release (how long until the compression goes and the signal is unaffected). The last piece is our makeup gain. Since we have reduced the signal and lowered the volume, we use our makeup gain to bring that entire compressed signal back to its original volume, where it would have been if it had never been compressed.
We’re always trying to get a cleaner, more present mix each time we’re behind the console, and a lot of that clarity comes from how we EQ our instruments. When it comes to EQ, we’re manipulating the tone of the signal by boosting or cutting certain frequencies in the spectrum so that we can create space for all of our vocals and instruments to fit together and blend well. It is always better to cut first and boost later. The way I think about it, by cutting frequencies, I’m fixing problems. When I’m boosting frequencies, I’m trying to feature a tone that’s already good. It makes the most sense to highlight the tones that are good by removing the bad tones, consequently leaving us with the frequencies we desire.
The purpose of the gate is to only allow certain levels of audio to come through to help reduce unnecessary noise which bleeds through the different microphones. Gating works very much like the name implies. Imagine walking up to a gate; you stand there and rest your hand against the gate and nothing happens. Then you apply some force and the gate pushes open. That’s exactly how a gate works in audio. Once the audio levels move past a certain point (threshold), then the gate opens up and allows audio to pass through. If you set your threshold too high, nothing will come through. If you set it too low, then everything comes through unaffected. You then control how quickly the gate opens and closes by using your attack, hold, and release times. Attack is how quickly the gate opens, hold is how long the gate continues to stay open, and release is how long it takes the gate to close and cut out audio bleed from the microphone. Remember, these times are all in milliseconds (just like compression) and are happening relatively quickly.
In terms of signal flow, I like to set my order of action as Compression, EQ, then Gate. I find it more useful to place compression first and then EQ what frequencies you don’t want. Otherwise, in an EQ first signal flow, your compressor could bring back some of those trouble frequencies you just tried to remove.
Using EQ, compression, and gate is crucial to getting your different sources to sound their best and work together in the context of your mix.