In this article we answer the question, What is a limiter plug-in? We break it down in to easily consumable parts to get you up and running with limiters.
Ever wondered what the plug-in in your DAW called `Limiter` is all about? Or perhaps you have given it a go and kind of know what it does, but you’re are still unsure as to how it works and when you’re should or should not use it. Today we are going to look into the limiter plug-in and try to answer your questions giving you the knowledge and confidence to use a limiter in your productions.
We will look at how a limiter works and specifically what it does to your audio signal. We will look at the common parameters on limiters you’re should know how to use and some examples of how and when to use a limiter. Finally, we will discuss a few tips and things to watch out for when using a limiter in your productions.
So let’s dive in and answer the question of What is a limiter Plugin?
How does a limiter work?
To start us off, let’s look at how a limiter works and what it does to an audio signal. Basically a limiter works by preventing any audio signal going above a specified threshold e.g. if the threshold is -1 db then any audio signal that is above this will be `chopped off` or reduced to a maximum of -1 db. A limiter is very similar to a compressor with a very high (almost infinite) ratio setting and in fact any compressor setting with a ratio of 1:8 is getting very close to acting like a limiter.
The main difference between a compressor and a limiter is the attack. A compressor has more of a natural sound reduction effect while a limiter is very harsh and acts like a Police Officer enforcing the speed limit (e.g. you’re cannot drive over 55 mph here).
Let’s take a look at a practical example, I have loaded up a drum loop into Ableton Live and then recorded the loop with a limiter applied, and then again with a compressor applied. I have tried to make the two recordings as equal as possible where the limiter has a threshold of -10 db and the compressor has a threshold of -16, ratio of 1:3 and 1.6 db of gain on the way out. The reason I did this really was for the visual effect, more so than the listening (which really is more important but I am just trying to illustrate a point) since I wanted the wave form images to match up. What follows are the wave forms and the audio loops so you’re can see and hear the differences between a limiter and compressor. I recommend listening to the original loop before listening to each of the compressed and limited loops for reference.
So as you’re can see from the wave forms the limiter is acting like we have discussed, not allowing any signal above the threshold through and so the wave form looks cropped at the threshold level. When we compare this to the compressed waveform, we can immediately see the difference between the two. The compressed wave form looks more `spiky` i.e. the initial attack of the signal gets through and then later the wave is pulled back to the threshold limit.
This is the key difference between compression and limiting, where a limiter is a hard stop at the threshold/ceiling and a compressor is more of a gradual reduction. Hopefully this also helps with you understanding of a compressor, where a compressor will still allow some punch of the drums through and apply a touch of `tightness` to the signal.
What are the most common parameters?
While there are many limiter plug-ins available on the market today, all with many or few controls you can play with. The main three parameters I think you’re should be most familiar with to understand how a limiter works are Threshold/Ceiling, Release and Gain. These settings might be called something different depending on the limiter you’re are using, but most limiters will use these names.
This is the level at which you’re do not want the audio signal to go over. In some limiters your will have either Ceiling or Threshold and in others you might have both like the W1 Limiter pictured below.
So if we were to take the W1 as an example, what is the difference between Threshold and Ceiling?
To answer this I jumped back into Ableton Live and did some recordings, this time I recorded 1 clip with the Threshold at -10 and another with the Ceiling at -10, below are the recorded and original wave forms.
Interestingly as you’re can see the Threshold recording has clearly been boosted after the threshold has been applied, resulting in a compression effect. This is not uncommon among limiters to do this and if you’re are familiar with compression this may not be a surprise to you’re. The Ceiling recording appears to have had a ceiling or limit of -10 db applied to the signal and nothing else. For me this demonstrated two points:
- In the case of the W1 the threshold acts similar to a compressor.
- The importance of knowing you’re plug-ins. Had I not done this test, I would not have known that the W1 applies some make-up gain to the out going signal after the threshold has been applied.
This setting controls the release of the limiter on the audio signal i.e. how quickly (or slowly) the limiter stops affecting the signal after it has fallen below the threshold. This time let’s take the L1 Limiter by Waves as an example. So, the release on this plug-in is only relevant to the threshold, that is to say it has nothing to do with the value of the ceiling parameter. In the below example I have lowered the threshold to -16 db and set the release to it’s lowest possible value (0.01).
In this example I have set the release to the maximum possible value (1000). Have a listen to the two and see if you’re can hear any difference.
To my ears I can definitely hear a lot more distortion in the recording with a short release compared with the longer release recording. But why? Well Let’s look at what is going on here! The release time is a value that represents a rate of change or the rate at which the limiter removes the gain reduction (just like in a compressor) once the input signal has fallen below the dialed in threshold. So in the case of a short release time this means that once the signal has dropped below the -16 db level in our case, the limiter will very quickly pulls back the gain reduction.
But don’t forget the gain boost!
So just like in the example with the W1 Limiter when threshold is applied, an automatic gain boots is also applied. All this results in distortion because the limiter is pulling off the gain reduction very quickly, then the Gain boost, `takes over` pushing the signal higher too fast.
Some limiters will include a gain control which is often used to control this gain boost we discussed above. This allows a user to dial in the exact amount of gain they want, rather than let the plug-in decide a value for them, this setting is often found on compressors too.
How and when can I use one?
Just like a paintbrush, you’re can use this tool in whatever creative way you’re like. Perhaps you’re like the distortion sound when you push the threshold and shorten the release, totally fine! The main thing here is to try different things out and see what works and what does not work. Below we will cover a few ways you’re can use a limiter keeping in mind these are just ideas, not rules for when you’re should use a limiter.
A common use for a limiter is in the mastering stage, where you’re can find it hanging out on the very end of a group of effects. Often a limiter will do little more than act as a backstop to the other effects preceding it just in case there is the odd signal that goes above what you want it to. The limiter adds no color to the signal nor does it change the signal in any way other than to limit it in volume.
One trick you might be able to get away with is using a limiter to remove sibilance and other harsh sounds from a vocal recording. In cases where you’re do not have a deeser plug-in or you’re do not want to have to draw in automation lines for gain and EQ, a limiter can apply gain reduction where needed. It can do so without compressing the signal like a compressor would. Give it a try for yourself on some dry vocal recordings or recordings where the speaker has prominent sibilance.
Make a Sausage
Maybe you’re are working on a synth sound and you want to pull out all the dynamics from it and make it as big and loud as you can. Well, you can do that with a limiter by pushing the input signal so that you’re always exceed the ceiling level. This will result in a sausage looking waveform. Keep in mind however this may not sound that nice to someone listening to your production and probably won’t sound as loud as other methods.
What to watch out for
Below are three things I think you’re should keep in mind when using a limiter in your productions, no doubt there are plenty more I should add here, and if you’re have any in mind you’re would like to share please do let us know in the comments below!
Get to know you’re Limiter
Just like we have done here in this article, take your limiter plug-in of choice and try out difference settings. Push it to its limits to see what it is capable of. Get to know when it starts to color you’re input signal like we saw with the L1 Limiter and the distortion it produced. The best plug-in in is the one you’re know how to use (just like with any software) so get as much experience with it as possible.
Use compression first
In most cases the most natural sounding type of limiting will be compression, so if you’re are having trouble getting the limiter to do what you want it to do, add a compressor first. Doing this can result in a much cleaner and natural sound signal, and reduce the amount of load on the limiter.
Only apply to transients – Don’t make sausages
A limiter really shines when it is used sparingly, and your will know you’re have your mix in a good place when your limiter is hardly working at all. When it comes to mastering you’re final mix don’t rely on a limiter at the end of your chain to sort everything out, this will result in `sausaging` your mix and having a very dull life less sound. I would recommend only applying a limiter to you’re master bus at the mastering stage (if at all). This will push you’re to sort out your mix beforehand because remember crap in = crap out.
So there you’re have it! A limiter applies gain reduction at an almost infinite ratio to the incoming signal, where the signal is over a specified limit. We have seen and heard how limiters work and what the most common parameters are. We also touched on a few examples of how and when you’re can use them, and what to look out for when doing so. I hope that from this article you’re now have more knowledge to use a limiter confidently in your productions. Perhaps you’re would like to share some of your work with the community here, if so leave us a link in the comments below!
In later articles we plan on gathering a few of the best limiter plug-ins for Mac and Windows in one place for you’re, so stay tuned for that!
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Thanks for reading!