EQ – Normalization – Compression – Limiting

Equalization, Normalization, Compression and Limiting

As a music producer or sound engineer, it is inevitable not to meet with these terms: Equalization, Normalization, Compression, and Limiting. What is the difference between equalizing and normalize? In what order do you normalize, compress, EQ and limit? Well, in this article, we’ll explain what each of this term meaning and what he does to better understand how to mix and master your pieces as a professional.



As you know, the equalizer (EQ) is used to adjust the tone or frequency response of an audio system to achieve the desired sound quality. In mastering, the EQ will serve to give a final touch to the final mix. If you have not done a good job with the EQ in the mixing stage, surely it is too late to correct it.

Using EQ can help a sound blend in or stand out when mixing music.

The mastering EQ has three primary objectives :

  1. Adjust the overall level of bass, mid and treble.
  2. Make the overall level of these three frequency bands sound more uniform.
  3. Enhancing frequencies to get a more natural sound.

Listen carefully and try to capture the weaknesses of the final mix? Too dark and without air? Make small adjustments at high frequencies. Does the bass rumble the subwoofer? Make modifications in that area. You see, we are not talking here of overlap or highlight a particular instrument or voice, that should be in the mix. Now you must focus on the overall sound of the mix, as a whole.

When using EQ, the big tip is to use your ears. If the tracks you play sound right together, then they often are, so trust your instincts and adjust the sound to each room and situation.


Normalizing is about adjusting the peak or RMS level to a desired value by applying a constant amount of gain to an audio track to bring the average or peak amplitude to a target level (the norm).

My definition of normalizing is to increase the overall level by an amount that will make the loudest peak(s) reach 0 dBFS. This leaves level relations between individual tracks or pieces absolutely intact.

If the audio is sufficiently quiet, it’s most likely that the small amount of quantization noise introduced from the normalization process will be outweighed by the reduced amplification required in the analog domain (which equates to less noise) to actually be able to listen to the music.

Normalizing does not always improve the consistency of perceived loudness. Normalization does not degrade the quality of the sound.


A compressor usually helps to get a fuller, louder sound without reaching the clipping limits. Some claim that you can’t employ enough compressors, but you must use them properly.

It’s not recommended to put the whole mixdown through a single band compressor, this usually results in pumping sound. Use compressors on single channels of your mix, especially on drums.

Again I recommend using at least 2 different compressors for your drum percussion sections. I always route high-frequency drums (Hihats, Cyms, Claps etc.) through one compressor, and the low-frequency ones (Bassdrums, Toms etc.) through another one.

You’ll have to experiment a bit with the settings of the compressor to get your results, there are no basic rules for that.

If you’re not familiar with the basics of audio compression, you should read our article Basic Compression Tips in Audio Mastering. Also see: How to use audio compression.


A Limiter is a compressor with a ratio set to a very high setting (like 1:16, or in some cases 1: infinite). This explains the term: the wave material is being limited to the peak volume defined by the threshold value.

You can get more transparent limiting using a multiband limiter, but be extremely careful!

Working with a multiband limiter is not too difficult. Just increase the input gain and watch the meters on the right, especially R, the gain reduction meter, and S, the saturation reduction meter.

Saturation reduction causes distortions, and gain reduction causes pumping. Finally, when you think some bands are affected more than others, you can use separate thresholds or band input gains for them.

Compression Vs Limiting

So what is the difference between these two effects? Depending on your outlook, either not much or a great deal. A limiter is usually set to a fixed threshold, and any signal that attempts to exceed the threshold is pulled back (attenuated) by exactly that amount needed to maintain the predetermined level.

If the input gain is set way high, then all signals below the threshold (including noise) are boosted – in the extreme case so everything is the same volume (again including noise!).

Limiters are “hard” compressors – the absolute level is fixed, and the compression ratio may be as high as 100:1 or more.

This means that the input signal must increase by 100 “units” to make the output increase by one unit. Many limiters claim that the ultimate compression ratio is infinity, however, this is probably an overestimation of the true figure.

A compressor uses much the same (or at least similar) circuitry as a limiter. While some compressors boost the level of signals below a preset threshold by a predetermined amount and reduce the level of signals above the same threshold.

This type of compressor is most commonly used in noise reduction systems – an expander is used at the playback end to return the original dynamic range.

Use your ears in all processes, trust them when they tell you that the mix sounds good. Rest when you work too much on the mix, if you exhaust yourself, you will lose the sense of the big things and make mistakes.

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See also: Best Free VST Compressors

3 thoughts on “EQ – Normalization – Compression – Limiting

  1. Avatar
    dave scott says:

    This is all a bit basic. If you don’t understand this stuff already then you really aren’t a technical producer. I don’t see any tips here at all….. just schoolkid level explanations of what the devices do.

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