EDITING & MIXING

GarageBand effects: Compression

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Compression on the Master Track         masterful

The Master Track controls the volume and effects settings of the entire mix. Some compression is usually needed here, and can be done using GarageBand's basic 0-100 compressor.
For more precise results, check out the Audio Units MultiBand compressor, which has nineteen parameters, and experiment with different settings.
See also next tip
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the Compressor Settings         Under Attack

GarageBand's basic compression only shows a slider from 0-100. This is ok for many situations, and a quick way of chieving good results, but it cannot give you the precision that a fully adjustable compressor can achieve.
But don't despair; there is a very capable compressor available as an "Audio Units effect" - in the selection bar under the instrument details triangle. Look for the AU Multibar compression, or import a new compressor from an Audio Units producer. (for details, see the GarageDoor: Audio Units Tutorial ).
The most important parameters are:
  • Threshold** sets the level where the compression kicks in. Sounds below this level are unaffected
  • Ratio** is: how much compression? Normally you'd use 2:1 for a mild effect, up to 6:1 for strong compression. Higher ratios are possible, but noticeable.
  • Attack** sets the time it takes for the compressor to kick in after the signal has risen above the threshold.
  • Release** sets the time it takes for the compressor to switch off after the signal has fallen below the threshold.
  • Gain** is used to make up for the loss in volume of the signal during compression.
Listen closely to the changes in sound while you tweak the settings. One affects the other, so it is important to take your time here.
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Attack & Release         Match play

The idea of setting the Attack and Release is to make the compressor come in and out unnoticed.
The best way to do this is to match the attack and release of the instrument or the signal: drums have very fast A&R so use a low ms number; synth pads on the other hand need to be matched with longer Attack and Release times.
Note that these can only be set in GarageBand's more sophisticated compressors, available as Audio Units in the Audio Unit effects selection box.
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Noise Gate         Sssssh....!

GarageBand calls the Noise Gate simply: "Gate".
It removes completely any sound (noise) below a certain level. Check your vocal track for example: it is probably full of clicks, shuffles, breaths and headphone spill. You can set the right noise level floor with the threshold command.
Using the Noise Gate is especially important after compression: compression always raises the noise level! This is because compression brings the soft sounds closer to the loudest and so it boosts any noise in the track.
The GarageBand standard gate only allows you to set a level between 0-100, but look for more subtle gate effects from Audio Units producers. These have:
  • Attack and release* - the same as for the compressor
  • Hold* sets the time the gate stays open after the signal has dropped below the set *threshold*
  • Range* sets the amount of cut off when the gate is closed



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Creative Compression         Punch

There are two ways in which you can use compression:
1) for dynamic control, the form of compression you will use most -- see below --- and
2) creative compression.
Creative compression means using this effect to change the sound of an instrument into something deliberately different, to produce a more interesting instrument sound. For this, you must use GarageBand's more sophisticated compressors, for example the Audio Units MultiBand compressor, which has settings for pre-gain, post-gain, cross-over, threshold, headroom, attack, release and EQ.

A common example is to make drums more punchy. Using a custom compressor (from the details: Audio Units menu) you set a slow "attack" and the compressor kicks in only after the "hit". This adds to the punch.
By experimenting with a combination of GBs gate and compression you will be able to get excellent customized drum and other sounds.
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Compression on the Bass          Even Steven

In order to provide a steady supportive bottom end, the bass must have an even sound.
Unfortunately, less experienced bass players often deliver a very fluctuating volume level: some notes stand out, while others are quiet. Compressing the bass at the editing stage will rectify this, delivering a full, steady bass at an easily controllable sound level.
Be careful, though, especially in solos and passages that make a feature out of the bass:
compression takes some of the dynamics out of a performance and you could kill a brilliant solo with too much compression! For this reason, edit compression is better than doing too much at the input stage.
As explained in the tip: "Creative compression" you can use compression to change the sound of the bass to produce a more interesting instrument sound. For this, you must use GarageBand's more sophisticated compressors, for example the Audio Units MultiBand compressor, which has nineteen parameters.
A common example is to make the bass more punchy. Using the Audio Units MultiBand compressor you set a slow "attack" and the compressor kicks in only after the note is played. This adds to the punch. By experimenting with a combination of GBs gate and compression you will be able to get excellent customized bass sounds.

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