Compression Flashcards
What is compression?
- a smart volume fader
- a tool to control the dynamic range of an instrument
- most commonly used to make loud sound quieter and quiet sounds louder to squid the overall dynamics and volume of a particular instrument
What are the 4 goals of compression?
- to balance
- to enhance
- to glue
- to fix
what is the balance goal of compression?
- in order to get a balanced mix, 30% of your job is going to be compressing your instruments well
- in the aspect of balancing compression you want to make the loud sounds quieter and the quiet sounds louder
- you’re trying to balance the dynamics of an instruments performance
- balancing your tracks is important because tracks with large dynamic ranges just pop in and out of your static mix at random
what is the enhance goal of compression?
- to enhance the tone of a particular instrument
- if the sound of your instruments are boring, the balance aspect of your mix may not matter than much
- tonal compression changes the sounds tone in some way such as making it punchier, thicker, flatter or change the groove of an instrument
- accomplishing enhancement is going to give you more exciting instruments and therefore a better mix along with it
what is the glue goal of compression?
- what takes a mix from sounding like a bunch of random tracks into sounding like a completed mix is glue compression
- glue compression brings out all of the instruments together to make them feel more cohesive
- a lot more vaguer than the other goals of compression alongside it being more of a feel thing than it is so much that is extremely tangible
- glue compression creates a sense of togetherness
- the way you carry out glue compression is by bussing several instruments together to a single track and then compressing that track making all of these instruments compressed at the same time creating a sense of unity
with is the fix goal of compression?
- a type of compression that can take away annoying sounds that focuses the listener on the song and not these problematic sounds
- some of these sounds fixed by compression cannot be fixed by automation / EQ
what is dynamic range?
- volume difference between the loudest part of the performance and the quietest part of the performance
what are the different dynamic ranges in mixing?
- musical dynamics
- macro dynamics
- micro dynamics
what are musical dynamics?
- the range of volume between the loudest part of the song and the quietest part of the song
what are macro dynamics?
- macro dynamics are the entire track of a performance to the quietest note to the loudest note
- macro dynamics is where you are going to start getting into compression as compression doesn’t really affect musical dynamics as that’s an artistic choice of whatever the song is
- but macro dynamics is where you begin to control stuff as you can bring down the loud notes and bring up the quiet notes
what are micro dynamics?
- the range of volume between the loudest moment and the quietest moment in every single note an instrument creates
how would you compress the micro dynamics of an instrument?
- we want to control its volume envelope
- the volume envelope is the unique pattern of loudness that’s made by each instrument
- every single instrument has a standard volume envelope
- all sounds in nature follow the same pattern of loudness though the shape of that pattern isn unique to every single instrument or sound source that produces these sound waves
- e.g. every single snowflake is a snowflake yet they are all unique
- this is the exact same with micro dynamics and the volume envelope
how is sound represented through peaks and valleys like a mountain?
- the peak of a sound (known as the transient) is the loudest moment of the sound which comes at the very beginning of a sound
- e.g. the initial pluck of a guitar string would be the peak as its the loudest part of the sound
- the peak is what gives a sound its punch/impact
- the valley (also known as the sustain), is the second half of the sound, it is the rest of the note
- there is an initial loud moment with the peak and then the rest of the note is the valley (the sustain)
- the valley continues until another transient occurs, or until the instrument runs out of energy
why can’t you hear compression?
- good compression comes in layers
- each of these layers are accomplishing a different goal and doing it subtly
- whilst a certain layer may not be that audible on its own, it does huge service to the mix as a whole
what is the threshold on a compressor?
- the volume level that turns on the compressor once the audio goes above it
- starts to reduce the gain once the volume has breached the threshold
- can be used to choose the part of the volume envelope / the part of the micro dynamics that you want to target
- you can use the threshold to target the peaks and then valleys of a note
- when you combine this with the different parameters of a compressor you’ll be able to achieve different styles of compression
- the threshold is fixed and does not move
- the ratio is fluid
what is the ratio on a compressor?
- how hard the compressor works after the threshold has been breached
- how aggressively the compressor turns down the volume
- as you turn the ratio up, the peaks and the valleys within the micro dynamics gets smushed closer to the threshold line
- the harder the ratio, the harder the compressor turns down the volume
- e.g. a ratio of 1:1 = for every 1dB that goes above the threshold, 1dB is outputted by the compressor (nothing happens)
- a ratio of 2:1 = for every 2dB that goes above the threshold 1dB is outputted
How would you turn your ration into a % for understanding of the gain reduction?
e.g. a ratio of 4:1
- create a fraction with the ratio making 1/4
- 1 - 1/4 = 75%
- so 75% of the gain that goes above the threshold is getting turned down by the compressor
what is the attack on a compressor?
- the amount of time it takes for the compressor to apply the full dose of compression, after a sound has gone above the threshold
what is the release on a compressor?
- the amount of time it takes the compressor to fully recover from the gain reduction
what does a fast attack do?
- grabs your peaks really hard
what does a slow attack do?
- lets you peaks pass through relatively uncompressed
what does a fast release do?
- makes your compressor alot more dramatic
what does a slow release do?
- makes the compressor more transparent
what is a fast attack time?
- 1-1000us
what is a medium attack time?
- 1-10 ms
what is a slow attack time?
- 10-100 ms
what is a fast release time?
- 0-100 ms
what is a medium release time?
- 100-500 ms
what is a slow release time?
- 500 ms- 20s
why are release times slower than attack times?
- because the valley of the audio lasts for a lot longer than the initial peak
what is makeup gain?
- simply turns up the volume of the output of a compressor
- a compressor has a function of making loud sounds quieter
- the make up gain is what makes the quiet sounds louder
- makeup gain is what is used for gain staging as without it, you’re going to lose volume from the initial track from the compression
- creates a thicker and dense sound with a loud and balanced break and valley
what is a side chain on a compressor?
- the side chain is the ears of a compressor
- the mechanism inside a compressor that actually listens to the sound going through it
- without the side chains there is no compression
- even though there is one side chain, there are actually two different sources for the side chain
what is the internal source of the side chain?
- the compressor listening to the channel that the plugin is on
- if the compressor is on a drum set, the internal source is the drum set
what is the external source of the side chain?
- when the compressor listens to a different instrument and acts as if it was compressing that instrument instead
- e.g. you may have a bass guitar and a kick drum, you may have a compressor on a bass guitar but you may tell your compressor to listen to the kick drum so that the bass turns down every single time the kick comes in
what is a side chain filter?
- tells the side chain (the ears of the compressor) to ignore a certain part of the frequency spectrum
- this doesn’t change the tone at all, it only changes how the compressor is working
- e.g. ignoring the low end on a kick drum
what are the lesser used parameters on a compressor?
- knee
- range
- hold
- threshold
what is the knee?
- turns the threshold from a single number into a range of numbers
- this of course makes the compressor generally less accurate but can also help your compressor to generally feel bit more natural
what is the range?
- affects the amount of compression that is being applied
- the range is just setting your maximum amount of gain reduction
- it basically sets the upper limit and keeps you from having insane amounts of compression
what is the hold?
- prolongs the peaks in gain reduction
- if a particularly loud spike goes through, it is going to compress that audio for a longer amount of time before allowing the release to do its job
what is the lookahead?
- a unique parameter in digital compression and something that can’t exist in the analog world
- the computer delays the playback of the whole session by a few milliseconds causing some latency in the entire session in order to pre-process the track
- in doing so, its able to see where every single spike in loudness actually is, it knows ahead of time when to turn itself open as it anticipates the peaks - causes gain reduction just before the loudness goes above the threshold
how do you set up your compressor?
1- set your threshold to 0dB
2 - set your ratio to its highest point
3 - make your attack and release as fast as they will go
4 - set the knee control to 0.0
5 - turn auto gain off / auto release off
6 - lower the threshold until you are getting short spikes of gain reduction at the beginning of each note. if the compression doesn’t return to zero quickly, you’ve gone too far
7 - adjust your attack and release times to match your compression style
8 - adjust your knee to make the compression feel more natural
9 - turn your ratio to 1:1, then slowly turn it up. Stop once you have the amount of gain reduction you want
10 - adjust your makeup gain to match your compression style
what is consistency style compression?
- meant to rebalance the macro dynamics
- the part of compression where you turn the loud stuff down and the quiet stuff up
- you’re not trying to change any micro dynamics or tone when carrying out compression for a consistent sound
- if done right, its subtle and something the listener can’t hear