Every Monday, we will be looking at one of these mastering topics. If you’ve missed one, click on the topic below to catch up:
This week, we look at Limiting.
Limiting is the last process in your mastering signal flow. It is here where you get your mixes up to commercial loudness to compete with the other masters out there. Here’s a couple of tips to get you started on your limiting process.
In part two of our mastering series, we talked about the importance of setting target levels by using VU meters. This is an essential step to help guide you to reach the loudness you would like to achieve.
Here’s a quick summary of the different target levels needed for the different genres.
- Classical 0VU = -18dBFS
- Jazz 0VU = -9dBFS
- Pop 0VU = -8dBFS
- Aggressive Pop / Hip-Hop = -7dBFS
When you are limiting and getting your mix to a target level, note that if your VU meter is hitting around 0VU, you are more or less hitting the desired loudness. If you go beyond 0VU into the red, you are pushing the loudness of your master and making it less dynamic.
Setting Up The Limiter
Every limiter has almost the same type of controls such as attack, release, gain reduction, input and output gain and its worth going through how we can apply this in a practical fashion. For the purposes of this post, I’ll be using one of my favorite mastering grade limiters, PSP’s Xenon.
Input & Output Gain
Output Gain: The output gain level is the limit where your audio signal doesn’t cross. In practice, you would want this level to be below 0dB FS to prevent any digital clipping. Before you start tweaking any settings, I recommend that you set the Output Gain limit to somewhere between -0.02dBFS to -0.2dBFS.
Input Gain: The input gain is the amount of gain that you are feeding into your limiter. The more gain, the more gain reduction, and the louder your master will be. To start off, slowly increase the input gain of your limiter till you reach your target level. You would usually need about 4-7dB of gain reduction to achieve this.
Attack & Release
Attack: Try to set your attack time to be as short as possible without loosing impact.
Release: The release timing is key in limiting. A long release time will cause a lost in level and pumping. Too short a release time will cause distortion artifacts. If your limiter has an auto release setting,use it as the limiter will be able to compute the best release time for your track.
The link control setting on your limiter decides if the limiter limits both channels equally (link control @ 100%) or totally independently (link control @ 0%).
With a setting of 100%, the limiter preserves the solidity of the bass and left/right balance of the mix. When the setting is unlinked (link control @ 0%), your master will sound wider and louder but that thins the bass and changes the L/R balance.
A good compromise would be to set the link control at 50%. However, if a mix has a lot of L/R interplay and difference, leave the link control to a 100% as you would not want to mess with its stereo image.
You will notice that to reach your target level, you will need at least more than 3dB of gain reduction. The more gain reduction you have, the more you will hear the artifacts of your limiter. In a good master, you do not want to hear the limiter working yet still achieve desirable loudness. Therefore, the recommended gain reduction limit you should have on the limiter should be no more than 2.5dB. But how do you do that?
In this day and age, when the loudness wars are still prevailing (it is getting much better though, thanks to loudness normalization standards in streaming) and clients want masters loud, professional engineers often use a clipper to add extra gain to their master. A clipper “clips” the mix to add apparent loudness to the master and the best one I know so far is by Kazrog called KClip.
How do you use it:
- Push your input gain of your limiter until you achieve your target level.
- Take note of the amount of gain at the input stage (for example, 8dB).
- Now call up the clipper before your limiter and split the difference between the two.
- You should have now 4dB of gain on the clipper and 4dB of input gain on the limiter and now, you should have less gain reduction on your limiter but still achieve the same loudness as before.
This guide should give you a good starting point to start limiting. Just remember not to over process anything.
Next week, we take a look at preparing your master to be sent out to labels / distributors / digital content providers.