Kim Lajoie's blog

Different types of limiters

by Kim Lajoie on December 27, 2010

Occasionally I see people confused by all the different kinds of limiters. Words like ‘brickwall’ and ‘Maximiser’ can confusing – especially when marketing material is heavy on hyperbole and light on substance.

It’s quite simple really.

A limiter is – at its essence – a compressor with a very high ratio and a very fast attack. While their technical design is similar (reducing the gain when the signal rises above the threshold level), their intended use is somewhat different. Compressors are generally used to reduce audible dynamic range – the difference between loud sounds and quiet sounds. Limiters, on the other hand, and designed to transparently reduce peaks. When a limiter is correctly used, it should not audibly change the sound (including the dynamics of the sound). Limiters are purpose-designed compressors that are specially tuned to transparently reducing peaks.

By reducing the peak level without changing the sound, limiters are ideal for reducing the headroom required by the audio. Limiters allow a hotter signal to be recorded with a lower relative noise level (signal-to-noise ratio).

Brickwall limiters are a specific kind of limiter that is designed to prevent digital clipping (signal going over 0dBFS).  They usually have instant attack and infinite ratio.

Clipping is a process sometimes used in mixing and mastering in place of limiting. Instead of reducing the gain of the peaks, the peaks are clipped (cut off or distorted). As you can imagine, it’s a much more extreme approach than limiting. I’ve written more about clipping and limiting here:

http://kimlajoie.wordpress.com/2009/07/07/limiting-vs-clipping/

The term ‘maximiser’ doesn’t have a specific meaning. It’s most often used as a marketing term to refer to a brickwall limiter that incorporates a blend of clipping to make the signal very loud. Sometimes maximisers also employ other processes such as tonal adjustment (such as ‘bass maximisers’), phase shifting or exciting (‘sonic maximisers’), analogue modelling (‘tube maximisers’), etc.

Don’t assume that the marketing material is a literal description of what goes on under the hood. Not to say that manufacturers lie, but sometimes the people who write the marketing material aren’t the people who design the algorithms.

-Kim.

4 thoughts on “Different types of limiters

  1. Russ says:

    Thanks, this was really helpful! I’d bene wondering for awhile about limiters because I sorta assumed they all did the same thing. Do you have any particular recommendations for limiters, in terms of brand? Does it matter, or do you think the standard limiter in say ableton is as good as the other pricy vsts on the market?

  2. Kim Lajoie says:

    It does matter. The subtle design differences between limiters changes the way they affect the sound. I don’t know the Ableton limiter specifically, but most limiters that come bundled with DAWs are pretty basic. If it works for you, that’s great – keep using it! On the other hand, if you feel like you’d prefer a different set of controls or a different sound colour, it’s probably worthwhile trying out a few different limiters.

    -Kim.

  3. Quick typo check: “Clipping is a process… As you can imagine, it’s a much more extreme approach than clipping.”

    By the way, as I’m sure you know, not all clippers are created equal. I’ve found that the “Clip” mode on Voxengo’s Elephant works very nicely without creating as much nasty distortion as “GClip”, for example.

    Cheers,
    -Bill

  4. Kim Lajoie says:

    Thanks for the catch! And yes, you’re right – not all clippers are the same. They’re simpler than limiters, but there are often differences in oversampling, curve, dynamic behaviour, etc – especially in tools designed for mastering.

    -Kim.

Leave a Reply

Your email address will not be published. Required fields are marked *