What Is Audio Limiter
Introduction
Probably the most primary rationalization of a limiter can be that it is a device that stops all audio (whether or not digital or an electrical signal) from exceeding a certain volume. Although it could actually function at any volume level, it is primarily used on the most allowed amplitude to keep away from the phenomenon of peaking.
Before we dive in a lot further, let me lay out the game plan right here. We’ll outline what an audio limiter is, and speak about its brother the compressor, after which clarify when you would need to apply to limit and methods to go about doing it.
After we’re done, you may know all the things you might want to know plus a little bit bit extra, all without an excessive amount of technical jargon and sophisticated language.
What’s the limiter and what it does to the audio signal?
Merely put, a limiter is a sort of compressor, and lots of standard compressors can even operate as a limiter. Limiting is a strict sort of compression that doesn’t permit the audio to transcend the threshold. Due to this, limiters allow us to go loud without clipping. They’re typically the final stage within the mastering chain, setting the ultimate level and making certain there are not any rogue peaks or spikes eating up the headroom.
That is opposed to a regular compressor which is able to permit audio to transcend the threshold based on the ratio. However, with a limiter, the ratio is fixed to an excessive rate such as 8:1 or above. Limiters will typically have a quick attack and release times to sound clear – avoiding the “pumping” artifacts typically related to regular compression.
The strict nature of the kind of compression present in limiters has spawned the time period of “brick wall limiting”. That is a reference to the limiter’s means to stop the signal in its tracks in addition to the appearance of the compressed waveform, which resembles a wall.
As you could expect, not all limiters are created equal. Some are designed particularly for mastering, some work better on drums, and a few are prized for their attribute tone fairly than their precise potential to compress audio precisely.
So selecting the best one for you is going to be a little bit of a problem. Whereas standard logic suggests you need to try a few out first, this isn’t all the time possible with costly software programs, and the demos won’t be useful enough that will help you decide anyway. Plus there are simply so many choices it’s hard to know where to start.
Types of Limiters
Compressor-limiters:
Typically, limiters are compressors with very aggressive settings. With ratios above 20:1, they permit only a fraction of the audio signal past the threshold degree. These limiters could or might not be geared up with the look-ahead function, and this will likely create a slight distortion or coloring of sound when making an attempt to limit loud transients. These limiters can be utilized on instrument buses similar to drums and percussions to make them sound larger.
Brickwall limiters:
Brickwall limiters have a set ratio of infinity:1. This means that absolutely nothing will get past the threshold (except there’s inter-sample clipping, for which there are peak limiters). Virtually all brick wall limiters have the look-ahead parameter. That is simply to make it possible for the gain reduction to be precise to the millisecond. These limiters are normally used as the ultimate step in most mastering chains.
Clipping limiters:
Both regular and brick wall limiters work on the idea of gain reduction. It’s primarily like turning the quantity knob down and back up in a short time to remain underneath the threshold. This occurs so rapidly that we barely discover it more often than not. If the attack and release times are usually not set completely right, there could be some pumping artifacts between transients due to the gain reduction happening.
Clipping limiters make this job simpler. As an alternative of lowering the gain rapidly and turning it back up, these limiters merely chop off the highest of the transients or something that’s loud. That is primarily clipping the audio for a really small period. As a result of this happening inside milliseconds, we understand this as harmonic distortion. In lots of types of music, this could be fascinating because it makes the transients brighter and retains the punch of the sound however the drawback is that it could not result in the cleanest of sound.
Limiter Parameters
- Threshold / Ceiling – That is primarily the “level” of limiting and the signal won’t transcend this level.
- Input gain – Increase the signal before it hits the threshold. This management is normally only discovered on limiters with a fixed threshold.
- Output / Make-up – That is used so as to add gain after limiting. Your limiter could automatically apply gain compensation, which implies the quantity will increase as you lower the threshold.
- Attack / Release – These allow you to change how rapidly the gain reduction reacts. Usually, you need very brief times for limiting. Many limiters will leave these settings fixed “underneath the hood” so you could not see these controls.
- Ratio – You’ll nearly by no means see this on a limiter either, the ratio is commonly fixed to a high setting and you can’t change it. However, in case you’re utilizing a normal compressor plugin as a limiter, you’ll need to set the ratio to at least 8:1.
Limiting in Mixing
Usually, limiters are only used sparingly throughout recording and mixing, as compressors are normally used to regulate the audio’s dynamics. However, they can be utilized as ‘safety‘ gadgets in an audio signal chain, as we described earlier, to stop the signal from clipping or distorting.
For instance, if we had been recording a vocalist who had fairly a large dynamic range (the difference between the quietest components and the loudest components), it could typically be tough to get the recording level good on the mixing desk or the microphone’s preamp.
So insert a limiter after the mic’s preamp to assist to catch the very loudest components simply before the signal goes into the red and distorts. However, this method ought to only be used as a final resort.
The first attempt to get a better recording signal on the source, both by turning down the gain degree on the desk/preamp, utilizing a different microphone, or working with the singer on their microphone approach (like moving away from the mic after they sing loudly, after which moving nearer when they sing softly).
In case you’ve used a compressor on a track throughout recording or mixing, and you discover that there are nonetheless one or two signal peaks that can be getting through, an option is to position a limiter after the compressor as a way to catch these peaks. Once more, it’s one other approach of limiting audio and ensuring that nothing is allowed to peak and deform within the recording.
Limiting in Mastering
An audio limiter is mostly used on the mastering stage of a record, where the limiter is used as the final processing machine throughout the entire mix. The ratio is fixed at infinite:1 – which means as quickly as the signal hits the desired ceiling degree, it can’t go any higher. That is often known as ‘brick wall limiting‘.
A mastering engineer will use a limiter to enhance the general degree of a completed track or album and squeeze as much quantity out as attainable. However, it’s essential to level out that the qualities of the sound are usually not affected – the one distinction is within the perceived loudness of the track that you just hear being raised.
When to use limiting?
Final Level Adjustments before Exporting
That is precisely what we looked at moments in the past – utilizing a limiter as the ultimate effect in your mastering chain to set a “ceiling” in your final audio. If you’re making use of no make-up or output gain, then the threshold turns into the ceiling.
It’s a good suggestion to aim for -1 dB, particularly as a result of when music is transcoded (i.e. transformed to MP3 or one other lossy format) it’s possible for clipping to happen within the conversion process.
Improve Loudness
That is associated with the earlier scenario, except loudness is a little more sophisticated than pure volume or ranges. Actually, loudness refers back to the consistency of the volume.
A sound that’s principally tender however momentarily loud can’t be thought of loud as a whole. However, a sound that’s persistently loud rightfully is loud.
This would possibly provide you with a hint about how limiting and dynamic range compression typically works. After we use a limiter, we’re not essentially making things louder. Actually, fairly often we’re making things softer, by guaranteeing the volume can’t go beyond the threshold.
Color and Character
That is very true for classic hardware limiters and analog modeling VSTs that add a bit of additional “mojo” to the sound. If that is what you’re after, there’s no need to push the limiter too hard right here. These models typically add delicate harmonic enhancement and should apply a point of saturation to achieve this.
Before evaluating, balance the volume in order that once you turn the limiter off, the audio is simply as loud as it’s with it on. It will allow you to make the right call on how the tone coloration is being affected. Whereas this can be a good rule for evaluating any effect, it’s notably related here as limiters dramatically have an effect on the volume.
Conclusion on What is Audio Limiter
Without limiters, it could be very hard to get our music to sound balanced on varied platforms and streaming services.
However limiters also can have a dark side – they will utterly drain the dynamics out of your audio and make it sound flat and lifeless. It might sound funny once you’re doing it just because it’s good and loud, however that is only a trick your ears are playing on you.
Whereas limiters could make things sound loud in a great way, you might want to be sure you don’t go too far here otherwise you’ll find yourself ruining your mix.
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