Written By : Limiters and compressors are in the same family when it comes to not only how they function but also in their effect. Essentially, from what I understand, a limiter is a compressor with the ratio set extremely high.
But for the sake of clarity, I’ll briefly dive into what the compressor is here because otherwise, you won’t understand what I’m talking about unless you take the time to read my piece on compression.
What Is A Compressor And How Does It Relate To The Limiter?
The compressor basically acts as an automatic volume control on your tracks. When the music gets too loud, the compressor kicks on and lowers the volume, and when it’s too quiet, the compressor brings it up.
It’s like there’s a tiny little audio engineer in your DAW whose job is to turn the volume down at the loudest parts and up during the quietest parts.
Using the example of a guitar track, if some notes are very quiet and some are really loud, compression will reduce the volume of the loud notes and increase the volume of the quiet parts, like – for instance – the sound of the pick hitting the strings.
If you think about it, whenever I play my PRS (on my Product Page), it produces a few different sounds, not only the music itself, but also the scratching of the pick up against the strings, and maybe even a little bit of fret buzz.
If an audio engineer has used too much compression on a guitar track, the sound of the pick hitting the strings can be just as loud as the actual notes, which is obviously an undesirable effect (unless you’re doing it on purpose).
The compressor brings a bit of balance and equality to your music’s volume. One can see just how useful this tool really is.
For that reason, some people really abuse it, and it’s important not to be one of them.
For the sake of this tutorial, we’ll speak on Garageband’s default compressor, which has four parameters: threshold, ratio, attack, and output.
The threshold is the point at which the compressor turns on; the ratio is how strong the compressor is working, the attack is how quickly the compressor works, and the output acts as a makeup volume.
In other words, the compressor’s make-up gain is ‘making up’ for the loss in volume as a consequence of decreasing the strength of the music’s signal.
Now that you know what a compressor is, let’s talk about what that means for the limiter.
What Is A Limiter And How Is It Different From The Compressor?
As I mentioned at the beginning of the article, a limiter is a compressor with the ratio turned up high.
In simple terms, it’s a compressor that is working harder than normal. It’s literally limiting the signal.
To reiterate, the ratio is by how much the compressor is turning the volume down, whereas the threshold is the point in volume where it actually starts working.
While compressors are typically used for increasing quieter parts of the recording, limiters act as a “ceiling” on the audio frequency. The limiter is reducing those intrusive peaks in volume at the end of our mix.
Like the compressor, it takes not only a thorough understanding of the tool to use it effectively, but also experience.
Explained one more time, a compressor is an automatic volume control, and a limiter is a ceiling/limit/brick-wall we apply after the use of the compressor at the end of the signal chain; almost as an emergency volume control.
***However, it’s important to note that limiters can be used in other ways as well. A limiter can shape dynamics, rather than acting as a limit on any unwanted sounds.
One of the biggest mistakes music producers and audio engineers make is they overcompress everything, mostly because of what has been called the “loudness wars,” which is where everyone is competing with each other to make music as loud as possible.
I’ve heard some suggest that compressing every track was a good idea
The reasoning for why this is the case is simple.
From what I’ve been told by others more advanced than me, Compression/Limiting has what’s called a “multiplicative effect.”
In layman’s terms, it means that if you’ve compressed each individual channel, the amount of compression is literally multiplying.
If you’ve set one channel’s ratio to 10:1, which is strong compression, and another to 5:1, the sum total of the amount of compression is not 15:1. It’s actually 50:1.
For this reason, it’s important to take it easy on compression as well as the limiter. When compressing more than one track, remember that it’s having a multiplicative rather than an additive effect.
Where Limiters And Compressors Are Used, How Not To Use Them, and Issues To Watch Out For
Taking the example of EDM, compression, and limiting is used quite a lot, due to the fact there is no need for as much dynamic range.
The music is meant to be right in your face immediately, at all times, and especially at drops.
Jazz music, on the other hand, does not need as much limiting or compression because listeners of the genre tend to want as much dynamic range as possible (learn more about jazz piano with PianoForAll)
By “dynamic range,” I mean the quiet versus the loud parts; the soft versus abrasive; the chill versus the intense parts.
Take a listen to your favorite jazz records, and then listen to something from an EDM producer.
EDM has a highly compressed pumping quality whereas jazz doesn’t. The two genres are on the total opposite side of the scale when it comes to compression and limiting.
If a limiter is set to, 0dBFS, the point of distortion, then nothing will go past that point, and therefore there will be no distortion at all in your mix.
Using a compressor or a limiter shouldn’t be a tool of compensation, however. It shouldn’t be a plug-in you slap on to your mix just because you read somewhere that you should.
Limiters and compressors should be used for a purpose, a pre-determined purpose you’ve already considered.
In most cases, we use a limiter as a sort of safety precaution.
For instance, if there has been a lot of processing on your tracks, there may exist some kind of dynamic error. Adding other effects like delay, reverb, and a chorus can amplify these errors.
Imposing a limiter is kind of like making sure that some of these errors are taken care of before they even start.
Clipping and distortion are something we want to avoid at all costs, and for that reason, we’ll impose a limiter on the very end of the signal chain.
What Do The Knobs On A Limiter Mean?
The limiter is different from the compressor as well in its controls.
Rather than a limiter using threshold, ratio, attack, and gain, it has different knobs. Using Garageband’s limiter as an example, there is the output volume and then the gain.
Gain
The gain knob is how much of a volume boost you’re giving to the track.
Output Level
The output level is the limit. It’s the point at which the signal cannot and will not pass.
Limiters use gain reduction in the same way as a compressor, but the main difference is that the limiter’s power is not decided by a ratio but by an output ceiling (limit).
Once you’ve set the ‘limit’ to a certain volume, the volume cannot, and will not go above this point.
From what I’ve read, in the past, analog limiters were less precise, but nowadays, with the use of DAWs and other digital equipment, limiters are very exact and people typically call them “brick-wall limiters” because of this.
They’re literally like a brick wall, nothing is getting through (hence the main image for this article).
Other Uses For The Limiter
While I never personally use a limiter for this purpose, other people actually use a limiter for uses outside of mastering (my guide). For instance, some mixers use the limiter as a way of boosting the perceived volume of a certain track.
Also, some use it for restraining tracks that have a little bit too much volume/dynamic range. Moreover, as I mentioned earlier, it can also be used as a way of ensuring there are no unpredictable sounds.
The next question is…
How Do I Actually Use The Limiter?
As I mentioned above, there are two parameters with Garageband’s stock limiter: the Output Level and the Gain.
The gain is by how much we increase the total gain/volume/amplitude of the music, and the output level is the point at which the limiter stops all signal from passing through.
A normal setting for a limiter would be +2.0dB for the Gain, and 0.0 dB for the Output level. This means that we’re increasing the total gain on the track by 2 dB and we’re stopping the signal when it gets to 0.0 dB.
From what I understand, anything higher than + 0 dB in the output level is clipping.
The cool part of using a limiter is that, when used properly, we can actually increase the volume of our final mix.
How Does The Limiter Increase The Volume?
Explained briefly, the limiter and compressor don’t actually make the song louder, they just increase the volume of the quietest parts and decrease the volume of the quietest parts.
It’s like we’ve squeezed the size of the signal into a smaller package, and then increased the total volume of that package. One can actually visualize what this looks like.
***By “Size Of Audio Signal In dB,” I meant, “Volume of Signal in dB.”
Using the make-up gain, we’ve increased the average volume of the song, so everything appears much louder, but it really isn’t in actuality.
However, it’s important not to think of the limiter as a tool for increasing the volume ONLY, because then we’ll approach it in a way that’s 100% appropriate.
The purpose of the limiter is to stop any clipping or distortion, and that’s the main thing. An increase in volume by a little bit is just a by-product. Approaching the compressor in this manner is good as well.
When using a compressor, think of it as a way of bringing up the lows and bringing down the highs, rather than just a tool of increasing the total volume (which some people do).
To illustrate everything that I’ve written here, just go ahead and bring up the limiter in your plug-ins and Garageband and turn the gain up to +20dB, and turn the output level up to 0.0dB.
You’ll notice that it sounds terrible, and that’s because the limiter is stopping the signal from exceeding the threshold you’ve set, but the gain is turned all the way up so it’s basically squeezing the life out of the music.
As a general rule, set the output level to 0.0dB, because that’s typically the point of distortion, and then turn up the gain to +2.0dB or +3.0dB to see what it sounds like.
Experiment by increasing the gain to see the point at which it stops sounding good.
As a general rule, I have my limiter’s output level to about -0.1dB, and the gain at about +2.0dB.