Compressor vs limiter – Which one should you choose?

Can you use a compressor as a limiter?

Do you feel like you are the only one who doesn’t understand  functions of a compressor vs limiter? what of their functions? Wait or how does one differ from the other? Well, relax as you are in the right place and you are not alone.

Before we look at some compressor vs limiter audio examples its important that we clearly define how a limiter functions and in doing that hopefully clearly explain the difference between compressor vs limiter.

Although compressor vs limiter both work by applying gain reduction to attenuate transients and dynamics, they do it in slightly different ways and it’s this difference that makes them suited to different situations.

A compressor uses a threshold control which lets the user decide where in the peak the gain reduction process starts, then a ratio control determines the amount the gain is reduced. This process is perfect for making the gap between low and high levels in your audio smaller and generally leveling the dynamic signature of your sounds. Compression is really at home treating vocals, drums and instruments that need some correction in their general dynamics.

Limiters also use gain reduction and just to confuse you a little more, can often feature a threshold control but the main difference here is that the gain reduction occurring in a limiter is not decided by a ratio control but by an absolute output ceiling decided by the use. Basically, this means you set the ‘limit’ and the level of the audio passing through the unit cannot go above this value.

Unlike compressors, which are best used for obtaining a more consistent level by reducing louder parts of the recording without squashing the peaks, limiters are best used for reducing peaks or spikes in the recording without affecting anything else.

In summary, limiters are much like compressors. They both process dynamic levels in pretty much the same way though the difference is that limiters have a much greater ratio. A typical compressor has a ratio of 20:1 or less whereas a limiter usually has a ratio of 10:1 to 100:1

What is audio compressor used for?

An audio compressor is a device that reduces the dynamic range of an audio signal. To effectively and satisfactorily serve its purpose, first, a threshold is established. When the audio signal is louder than the already established threshold, its gain is reduced. The amount of gain reduction applied depends on the compression ratio setting. For example, with a 2:1 ratio, for every 2 decibels the input signal increases, the output is allowed to increase only 1 decibel. However, there are a variety of other parameters in the compressor will also affect its performance in processing specific signals; attack time, release time and others are very important. There are a variety of uses and applications for compressors, the most obvious one being to control the dynamic range of a live performance so that it will fit into the fairly narrow dynamic range of recorders, etc. Other applications include making a signal’s average level higher, increasing the apparent sustain on a guitar, evening out a vocal or bass guitar performance, fattening up sounds, and on and on.

What does a limiter do in audio?

The audio limiter is a very similar tool to the audio compressor in that it reduces the dynamic range of a signal that passes through it. A compressor gradually reduces the signal level above a certain threshold, but a limiter completely prevents a signal from going over a specified setting – a limit that nothing can go over.

In practice, a limiter is basically a compressor with a very high compression ratio (20:1 to infinity:1). The idea is that once the level reaches a certain point, the limiter will not let it go beyond that.

What does a limiter do in recording?

When recording things like vocals or guitars it is usually advisable using a very gentle limiter. You can set the limiter so that it catches and prevents any of the signals from clipping and distorting – it’s a very useful way to ensure your recording signal doesn’t go ‘into the red’.

You’ll find dedicated limiters in most studios these days, both as hardware devices and as software plugins, and your own home studio DAW will likely have numerous limiter plugins included with it.

Can you use a compressor as a limiter?

I can tell you that understanding a difference between compression versus limiting is one of the key milestones in your progression as a mixer. After all use a limiter where you should be using a compressor and your mixes might end up in a big mess. Fortunately, breathe a sigh of relief because a compressor can also be used as a limiter if you set it up accurately and appropriately with certain settings.

What are the audio compression techniques?

Compression is a tricky subject for many, and there is no “one” great method for any situation. Compression is subjective depending on what you are workings with. However, I’m going to give you a few quick “go-to” compression techniques when you want a specific sound.

Technique 1: Flattening the Vocal

Basically, if you need to make the level of the vocal extremely level and unchanging then compressing the complete waveform is needed. By turning the threshold all the way down so it affects the whole signal makes each and every phrase compressed. This is not a particularly good sound, but if your singer doesn’t handle dynamics well then you might need to keep him flat. Also, using this type of compression in rock and metal tracks can keep the vocal from being drowned out by the instruments in the track.

Technique 2: Making a Kick Snap
Similarly, by just slowing the attack time you can get that snap in without the compressor clamping down on it. A slower attack time is usually more desirable to get the beater through, although there are sometimes where you might want an earthier, rounded bass drum tone.

Technique 3: Timing the Snare to the Track
A great technique to make your drum track breathe is to compress the snare drum in time to the track. A snare drum that breathes in time with the track pushes the drum sound forward and just makes it sound tighter.

Now, if we want to compress it in time with the track we are really only using the release parameter of the compressor. We obviously want a nicely compressed snare drum so we’ll put a little compression of 4:1 with a gain reduction of a few decibels. You don’t want to dull the attack of the snare drum so put the attack all the way fast and then slowly pull the attack slider back until the “snap” of the snare hit comes through. By playing with the release you can make the snare compression breathe with the track. Think of it as trying to make the snare drum exhale with each hit. You want the compressor to let go just as soon as the next snare hit occurs.

Technique 4: Fitting in the Vocal
Sometimes you don’t really want to compress the vocal but it seems like you just pasted the vocal on top of the track. There are just a few peaks in the vocal phrases that stick out just a little too much. Using compression to just push the vocal a tiny bit into the track to make it all gel together is what you need to do. But what kind of parameters do you need to set your compressor to if you want to achieve that?

When you listen to a short example of a very sparse track that only has piano and vocal. When you are working so so few elements it’s all the more important to make them fit together.

Sometimes you may find that there are just a few peaks in the vocal track that jump out or kind of jump on top of the track instead of blending in, so we must be careful when we’re applying compression to them. We just want to take care of those peaks, not really using compression as an effect—more as a level handler.

In some cases, don’t let the threshold deceive you when there’s is actually not a lot of compressions since a vocal track might have been recorded too softly. If you have a low-level track you need to compensate the threshold accordingly. If the sound source isn’t loud enough to go past the threshold there will be no compression.

Try to just compress those peaks if you want the compressor to react quickly. A fast attack will enable the compressor to clamp down on those peaks immediately and a fast release will also help to minimize the effect the compressor has on the rest of the signal, or phrases. The ratio is fairly high since we want to flatten those particular vocal phrases and the compressor is set to Peak.

Technique 5: Making a Kick Thump
Once again, the attack and release can shape your sounds differently. For instance, if you want a thumper kick drum, one that’s more meat than bone then a fast attack will cut off that initial snap in your kick drum sound.

If we want to reduce the snap from the beater and give it a mellower and rounder sound we would make sure our compressor had a fast attack. By cutting down fast on the initial beater attack we accent the boom of the drum much more than the snap of the beater.

Conclusion
I hope some of the examples above have shed some light on compressor vs limiter. The different ways compressor vs limiter functions for example, compression depends on the situation in its application, sometimes a tweak in the attack and release time is all you need. Other times you need to flatten out specific parts by heavy compression across the board or just subtle peak compression to make things fit.

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