#5
Compression
An extremely important aspect of audio, it's critical you do this correctly! So many times in my own music I setup compression, but never took the time adjusting them properly out of eagerness to finish the track. I'm not the only one to do this!
Rushing makes mistakes, patience makes perfection. You're better off working slowly and correctly.
I won't bother explaining gain ratio, threshold, compression ratio, or signal envelope. Who cares about technicalities? All you need to know about a compressor's attack and release, is how fast or slow it reacts to the signal. You want its attack to go through and the release to prolong the sound. That's it.
Vocals usually sound better with slower compression but adjust the setting until you find the balance; too slow can distort the signal.
Compression beyond 6dB is good for controlling dynamics rather than the soundfield.
Compression 1 to 2 dB is useful for adjusting sonic blends.
Compression 3 to 5 dB is useful for woodwinds, depending on which ones you're using.
Electric guitars, vocals, microphones and drums can be given up to 20dB, based on taste and genre.
Compressors with Numbers
Type————Ratio————Attack———Release
Kick————2:1—————1/64th————1/16th
Snare————2:1————1/64th————1/16th
Subgroup——2:1—————1/64th———1/16th
Guitar———varies—————varies———varies
Bass————12:1————1/32nd———1/16th
Mix bus———2:1————1/16th————1/16th
Vocals———4:1—————1/6th————1/4th
Woodwinds——4:1————varies————varies
Brass———6:1 to 15:1———varies————varies
Strings———1.1:1 to 2:1——varies————varies
Tom Toms——5:1—————varies————varies
Choir————4:1—————varies————varies
Epic Choir——8:1—————varies————varies
Keyboard——varies————varies————varies
Others———varies————varies————varies
Higher ratio + shorter attack + longer release = more aggression.
If you still don't get the sound you like, adjust ratios until suited to your tastes.
Types of Compressors
Dynamic Range Compressor
Reduces audio source signals to prevent their loudest parts going too high. As with all plugins, you set it to each instrument. They often are set to a ratio of 4:1 to 8:1 but you are free to adjust anywhere you wish. If set 1:1, nothing happens.
Digital Compressor
Most compressors nowadays are digital. Even the free ones are vastly more powerful than their analog forefathers, which were often limited in function. This is why it's best to have a couple compressor plugins just in case one doesn't work well for whatever instrument or song you're working on.
One advantage analog compressors have is they do not increase latency in PCs, though modern PCs usually won't have latency issues anyways. They also look cool to have lying around your bedroom! Realistically, analog compressors are a thing of the past, but if you ever find one that's cheap or free, may as well keep it for rule of cool.
Optical
A tiny lightbulb and photocell in the compression circuit that slows attack and release; useful for soft, warm, atmospheric, or emotional music and LoFi.
Useful for key moments in a song where warmth is needed; usually not good for kicks or snares.
Available in digital plugins, too.
FET (Field Effect Transistor)
Fast, aggressive compression useful for music that is dramatic, dynamic or adventurous.
VCA (Voltage Controlled Amplifier)
Fast, aggressive compression useful for drums, percussion and bassy sounds; can lack weight so often requires additional heaviness elsewhere (e.g. more reverb or left side of EQ raised).
Vari-Gain
A compression that reacts slowly and heavily, but lacks dynamics; good for bass and bassy instruments.
Multiband Compression
Splits signal into two to six frequencies, each with a different compression, allowing easy balancing and clarity, but becoming obsolete from dynamic EQs.
An alternate to multiband compression is a dynamic EQ plugin, such as the free ZL EQ or TDR Nova.
Examples of free multiband compressors are Uraleq by Flandersh Tech, HY-MBMFX2 Free, or ReaXComp by KVR Audio.
Whether you stick with the easier Multiband Compression, or the more complex dynamic EQ for greater possibilities, is up to you!
Parallel Compression
Contrary to its name, this isn't complicated. A parallel compressor sends its signal to another channel via auxiliary, bus or mult, or some other patchpoint, then adds compression only to the second channel. This uses both the natural sound and the compression, offering a balance of punch and control.
Useful for kicks and snares.
Useful for any instrument where the mixer feels a balance of punch and control is needed, or is their preference.
OTT by Xfer Records is a good free parallel compressor.
Hypercompression
When too much compression or limiting is used, the audio becomes flatlined, soulless and boring; since this can't be undone later, use compression sparingly!
Sometimes used for horror or cinematic moments.
Bus Compressor
A stereo compressor across the bus mix, to address complaints of why songs sounded different after the studio back in the day. Only use after you finish all other audio issues. Easy to overdo so be sure to use sparingly; often you won't need with any more than one or two dB.
Bus compression is unique in that you can add it after finishing the mix to reduce its impact.
Ratios
If you want more punch and aggression, set ratio low.
If you want control and emotions, set ratio high.
Drum Ratios
Drum kick & snare: ~1.5:1 to ~2:1
Other drum parts: ~4:1 to ~8:1
Low ratio for punch (rock music, heavy metal, action), high ratio for control (jazz, orchestral drums, emotions).
Like everything, tastes and preferences are unique per person; you are free to experiment with different ratios and combos at will.
Note: Digitally produced drumwork is much easier to mix than real drums, but lacks the true depth and power of real acoustics.
Manually Get Attack & Release
Set attack slow, set release fast, until high frequencies go dull then go back until balanced to your tastes.
Then increase release time until its sound diminishes, then increase so it flows smoothly with drumbeat.
Adjust gain until same as bypassed signal; readjust gain until smooth with the song's pulse or rhythm or on desired outcome.
Sidechain (aka Key Input)
A separate input that connects other plugins into the compressor; e.g. an EQ set into the compressor's sidechain becomes a de-esser, allowing you to clear up vocals and increase rhythmic elements if you so wish.
You can also 'duck a track' in this manner. Airport speakers duck musical tracks during announcements. This is also done during radio advertisements. Since you probably aren't doing any of that, we won't worry about ducking tracks, but still worth mentioning.
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Beginner's Mixing & Mastering
Non-FictionA simplified yet thorough guide across mastering audio, mostly geared for musicmaking but also useful for audio books, voice acting, SFX, and improving sonic qualities for videos.
