An audio compressor as the name implies is used to reduces audio signal’s dynamic range. A brief history of audio compressors, in early days, before audio compressors were introduced mix engineers had to constantly increase and decrease the gain fader of mixing consoles to control the audio levels.
After compressors introduced to the music production world, it became one of the secret weapons of early and today’s mix engineers.
What is Dynamic Range: Dynamic range can be defined as the ratio between the loudest possible audio level and the lowest possible level.In simple words, the difference between the softest part and the loudest part of the incoming audio signal is known as dynamic range of an audio signal.
The best example is vocals if you observe any vocals and see dB/VU meter you will see that softest peak at -13 dB and loudest peak at -5dB. Your job is to control these uncontrolled peaks and one of the tools you will use is the compressor. It is called “Dynamic Processing”.
Lots of vst compressors are available in the market from free to most expensive.
Before using this powerful dynamic processor, let’s see what are some common components and how these components work. No matter what type of compressor you use, you
No matter what type of compressor you use, you will find all or few of the following names on your compressors.
Components of audio compressors:
THRESHOLD: The threshold is the level at which compressors start working. For example, if you set the threshold to -10dB it will only compress the audio goes above -10dB and all the audio below -10dB will unaffected.
RATIO: The compression ratio is the relationship between the output level and the input level. In other words, the ratio sets the compression slope.For example, a 3:1 ratio means that for every 3dB the signal rises above the threshold only 1dB will be heard above the threshold, a reduction of 2dB will occur. 20:1 and above is called limiting nor compression.
ATTACK: Attack sets the speed(slow/fast) at which the compressor acts on the input signal once the signal has passed the threshold, attack parameter usually measured in milliseconds. Set attack parameter to slow to preserve transients of your audio. It is very helpful when you want your audio’s transient unaffected or minimal affected.
RELEASE: The Release parameter or knob determines how fast or slow the compressor stops processing once the signal rise above the threshold, it is also measured in milliseconds. You have to use release knob very carefully if the release is set to fast setting it will produce choppy sounds. Long release setting and usually produce overly compressed “squashing” sounds.
KNEE: No, Not your grandpa’s knee. 🙂 oK. Some compressors have knee setting which can be set to either “HARD” or “SOFT” settings. The term “knee” refers to the way the compression curve bends at the threshold point. See the image.
With hard-knee compression, the gain reduction applied to the signal occurs as soon as the signal exceeds the level set by the threshold. With soft-knee compression, the onset of gain reduction occurs gradually after the signal has exceeded the threshold.
MAKEUP GAIN or GAIN: When you use the compressor on audio or midi tracks, it usually results in the overall audio level reduction. So, Makeup gain or gain knob on some compressors allow regaining the reduced audio level.
MIX(DRY/WET): Not all compressor vst have mix knob. Mix knob is every useful knob when it comes to PARALLEL COMPRESSION.
Parallel Compression is a technique that involves mixing a lightly compressed signal with a heavily compressed version of the same signal. This allows for a smoother result, with crisp and level sound in the high end without any loud peaks or squashed transients. A typical ratio might be 50% of each signal.
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Use faster releases when compressing drums and other percussion instruments. This helps tame the transients but maintain the decay of the original sound.
When applying compression on acoustic guitars, try slower attacks for a picked or plucked acoustic, and faster attacks for a strummed acoustic.
Now you know basics of audio compressors you can manipulate this most popular dynamic processor in your favor. Share this post with your friends and family if you find this post helpful.