Use of Compression

Full band compression:


Multi band compression:


First, let's define Compression.

The reduction of audio dynamic range, so that the louder passages are made softer, or the softer passages appear louder, or both.


Compression settings:

Threshold: (eg. -40 to 0 dB)
Threshold: Level at which the compression is applied.

Ratio: (eg. 1:1 to 00:1 (which is limiting))
Ratio: Measure of cut, (e.g. 1:2 = 1dB cut for every 2 dB over the threshold)

Attack: (eg. 0.1ms to 200ms.)
Attack rate: rate of how fast the compression takes place.

Release: (eg. 50ms to 3 sec)
Release: Rate at which the compression backs off.

Knee: (eg. hard and soft)
Knee: Compression level intensity.


Now, for the basic two rules:

Rule #1: There are no rules. If you want to use a compressor/limiter of any type, then go ahead and use it.

Rule #2: When in doubt, don't use it!

> How can you tell when you have enough compression?
Discussing sound is like describing colors to a blind person, but let’s try.

Supposing there are two qualities of music, one called punchy, the other smooth.
Let's say that some music sounds better punchy, other music sounds better
smooth.
In general you can achieve a punchy or smooth sound through different amounts and types of compression, or not using compression at all.

> Try to avoid overall compression in the mix until mastering all songs on your album.
> Use individual compression on certain instruments or singers.

Technical reasons to avoid overall compression on your song:

> Save decisions on overall compression and individual tune equalization for an expert CD mastering person: (Unless of course you don’t plan on sending it to one. In that case, save 2 versions. One with, and one without overall compression.
Reasons:
1. The mastering house will have a more appropriate quality compressor for your music.
2. They will likely be more experienced than you about the compromises, advantages and disadvantages of applying overall compression.
3. They’ll be able to do all of this in a non-destructive way. In other words, they will be able to undo anything.
4. If you apply overall compression to your music, and your choice of compressor & or settings was wrong, the mastering house will have a difficult or impossible time attempting to undo the damage.
5. The more you compress your mix, the less the mastering person will be able to compress it, using the appropriate settings.

Dynamic Range--The Ups and Downs of Music:

Before we can study the art of compression, we must learn to appreciate the power of music's dynamic range. How does music grab our interest?
> A production which is relentlessly loud (or relentless in its sameness) can become boring very fast.
> Musical styles that depend on constant sameness become old very fast. (Disco died because it became boring, and over-compression contributed to its death. Rock hasn’t died yet, decades later, one reason is because it’s lively in dynamics.
> Any genre that does not grow in musicality will quickly die, and dynamic contrast plays a big role in musicality.

> Musical interest can grow and avoid sounding tiresome by expanding its dynamic range. Low levels create suspense that make the loud parts sound even more exciting. Four big firecrackers in a row just don't sound as exciting as 3 little cherry bombs followed by an M80.
This is what I mean by dynamic range.
A lot of music lately, especially that played on the Radio, are currently too compressed, but it sure turns some people on at home, and also in the motion picture theater.

> Films provide an ideal framework to study the creative use of dynamic range.
The public is not consciously aware of the effect of sound, but it plays a role in a film's success. For example, the movie The Fugitive succeeded because of its drama, despite an aggressive, compressed, fatiguing mix. From the beginning bus ride, with its super-hot dialog and effects, all the crashes were constantly loud and overstated, completely destroying the impact of the big train crash. They forgot the term "suspense"?
In contrast, the sound mix of the Titanic was a masterpiece of natural dynamic range. The dialog and effects at the beginning of the movie are played at natural levels, enhancing the drama and suspense for the big thrills at the end.
That's where the excitement lies.

Compressors: Tools to Manipulate Dynamic Range:

Compression is a tool; when used right, can produce some of the most beautiful recordings in the world. A lot of music styles are based on the sound of compression, from Disco to Rap to Rock. And a engineer may intentionally use creative compression to paint a mix and form new special effects.

But too often, unskilled compression squashes the sound, removes life, vigor and impact, and replace it with mush.
It actually takes more work to make a natural-sounding recording than an artificial one.
> First learn to paint naturally; then can you truly understand the art of creating distortion.
> Learn where compression is useful, and where it does a dis-service to the music.
> A compressed production may sound good on a boombox, but when reproduced on a high-fidelity system, it can sound overbearing and ultimately lifeless.

- Everyone has his own style of working with compressors and there are no rules. However, before you make your own rules, go slow on using compression too much! This learning process will teach you to make better-sounding music later on. Thus the compressor becomes a tool to handle problems, not a crutch or substitute for recording techniques.
> First, learn about the natural dynamics of musical instruments, then begin to alter them with compressors.

> Every so often, give yourself a reality check. Try bypassing it or pulling back the amount and see where you stand. You'll rediscover what is called the dynamics of music. It's a real challenge.

Watch For These Compression-related Pitfalls.

> When recording vocalists who have to belt it out now and then, a well-adjusted compressor can make them sound a lot more comfortable.
> For live mic’ng, watch out for a "closed-in" sound, "clamping down" when the vocalist gets loud, or loss of clarity.
> For Recording to tape or PC, compress at the mixing stage, not while recording. Remember, when recording, you cannot undo the damage of over-compression.
> If you are compressing up to 10dB or more, you are most likely over-compressing and as a result just bringing up the noise floor. A good compression range to stay around is 5 dB reduction.

> Start fresh each time you are gonna use compression. Free yourself of preconceptions. Although you always compressed the bass a certain amount, maybe this time you won't need that much compression. Each musician is an individual. In general, the better the bass player, the less compression you will need to use, and the greater the chance that compression will "choke up" his sound.
> In pop music, compressors are often used to create a tighter band sound, making the rhythm instruments sit in a good, constant place in the mix. But when misused or overused, compressors can take away the sense of natural breathing and openness that makes music swing and sway. Thus, I recommend that during mixing, after you've inserted a few compressors on certain instruments (e.g., the bass, rhythm guitar, vocal) and listened for a while, try comparing with the compressors bypassed. Sometimes you'll find the compression was hurting the mix, and not helping the sound.

Avoid Wimpy Loud Sounds:
Some of you may say that this conservative advice only applies to acoustic styles like country music. However, Rock music is often a casualty of compressor abuse. Some engineers try to be get louder and louder and reach a climax, but
have lost their intensity, producing wimpy loud sound. Always strive to put life into your sound. When you mix rock music, listen closely to the climaxes; is it possible that you are killing the music with your compressor?

Stop trying to copy squashed CDs. Many compare their mixes against already-pressed CDs, but be careful what you choose as a standard. Ironically, mastered CDs often do not sound like what comes out of the mix, so how can you emulate something which can only be done post-mix? What you really need is to hear the sound of a good mix before it was sent for mastering. But since that's not available, turn down the CD reference.

Remember this: when two CDs are listened to at equal loudness, nine out of ten people will prefer the sound of an uncompressed song to a over compressed one. For the first minute, a louder presentation will grab you, but relentless
sound quickly becomes tiring. Many of today's compact discs have already exceeded the loudness limit---which is the level above which the sound quality goes downhill while the sound "quantity" goes up. You can't get something for nothing.

If You Can't Make It Sound Good, Make it Loud? (Nope)
Compression is not making a song louder & hotter than the competition. Compression is the process of making a song better.