Four Steps for Song Mastering and Improving Loudness
After you mix your song — assuming the mix is well-balanced and not peaking — the mastering process is where you fix the volume problem. I work with Mac’s Logic Pro, but these components below are fundamental to any quality software like Pro Tools, so you should be able to find equivalents there. If you’re running a free audio software with fewer resources as far as effects and plug-ins, some of these tools may not be possible to execute. Even if you don’t have the tools below, the four-step process gives you a feel for the flow of mastering, as far as which areas of the song to work on first and what order you should follow as you shape the track.
Step 1. Multimeter: Get a Lay of the Land
A multimeter gives you a helpful bird’s-eye-view of what you’re dealing with in your track. It’s like a spy spying on a foreign land before the army invades. You’re gaining intelligence before you do anything. It also might tell you if your mix is so bad that you shouldn’t even waste time mastering until you’ve gone back and completed a better mix. In the long run, the multimeter can save you time and prevent painful I-just-wasted-three-hours-of-my-life-and-it-still-sounds-terrible moments. All of the mastering techniques in the world — even the high-end recording studios — will not fix an awful mix or recording job.
After you’ve imported your mixed WAV file into a new, blank project, add the “Multimeter” plug-in to your track’s channel under the section labeled “Inserts.” Open the multimeter and note two features that it has: the Analyzer and the Gonometer.
Click on the Analyzer to get a visual analysis of the entire frequency spectrum of your song. It will show you if anything is clipping (and if so, go back and do another mix) as the frequencies turn orange or red. Hopefully you won’t be seeing orange or red alerts that indicate clipping. The analyzer also shows you the volume of the track (on the far right), and it also has a “correlation” meter, which looks for anything out of phase in your recording Long story short, if something’s out of phase, it will make the heads of listeners explode because it messes with your brain’s perception of sound and, as the professionals say, is “annoying.” For the correlation meter, if the marker is staying on the right side in the blue, that’s perfect. If it’s going to the left side in the red, it means you’ve got out of phase issues. If this is the case, don’t master. Call your nearest audio doctor in your town for emergency help with your recording or Google how to fix out of phase recordings. Don’t have time to cover it here.
The Gonometer shows you how centered your song is. No, not in the weird New Age sense, in the panning sense. It gives you a visual picture of it. If way too much audio is panned to the left, for example, the gonometer will show your song as a lop-sided-to-the-left blob. You need to re-mix and make it less lop-sided.
Step 2. EQ: Do a Little Landscaping
Generally, audio folks like to use the mastering phase for boosting wanted frequencies in EQ. Mixing is where you localize the bad frequencies in your song and cut them. Either way, everyone has their bag of tricks for EQ-ing, and I published mine in a previous article here. I learned it from former MIT-professor Curtis Roads, which means the recipe is, well, amazing. It doesn’t magically fix everything, but it has never caused my songs harm. When you work on your EQ, you may want to leave some frequencies weaker than others in the song depending on the style of music you’re doing, but generally the EQ step is a chance to look for any weak spots in the frequency spectrum of your song (minus any specific frequencies you do not want at all) and boost those weak areas so that the song feels well-represented in the entire frequency spectrum of EQ.
As always, rely on your ears primarily, not the visual. The visual is just there to assist you, but it’s not the ultimate authority. Sound has a way of doing strange things that don’t always mesh with what we’re seeing visually. So start with all these visual tools, but then double-check things with pure listening.
Step 3. Multipressor: Squash the Moles
Have you ever played that whac-a-mole game at an amusement park or fair? The multipressor is basically the whac-a-mole of compression. As a refresher, remember that compression simply squashes signals in your song that are spiking in volume compared to other points in the song. It evens out the playing field so that not one point in the song is dominating everything else with ear-shattering loudness. Basic compression, where you apply one compression effect to the overall track, does a simple analysis of your mixed-down track and tries to squash peaks. It’s like a guy with one giant hammer swinging at the moles without really aiming. He’s just focusing on strength. That’s an imperfect analogy of a basic compressor applied to your overall track. It’s not always precise, but it does squash things. A multipressor, however, attacks your song with multiple compressors-in-one that allow you to target four different areas of your song’s frequency spectrum and customize a compression set-up for each of those four areas. So if you want to compress the low frequencies in a different way than the mids, you can do that. It’s more precise. It’s using those smaller, more precise hammers to play whac-a-mole and aiming for individual moles with accuracy as their heads pop up.
Here’s how I operate the multipressor:
1. After you’ve added the Multipressor as a plug-in and opened it, play your song (loop it continuously if you have to). Work from left to right, from the #1 compressor (which handles the lowest frequencies) to #4 compressor (highest frequencies). Locate the parameter marked “Compr Thrsh” (Compressor Threshold) and slowly move it down until visual display above starts to flicker as the #1 compressor begins to find peaks and squash them. It’s just a little flicker of movement. It doesn’t need to be huge squashing of the signal. Once you see this, stop moving the threshold down. Count how many dBs you’ve moved the threshold down, and then move the “Gain Make-Up” up by the same amount you moved the threshold down. However much the threshold has to go down (before beginning to squash peaks) that’s how much the gain make-up goes up.
Do this same operation with all four compressors. #4 compressor usually takes large amounts of threshold and gain make-up — just a warning. The high frequencies are always the weakest, and they easily get buried if you don’t make-up the gain that was lost when they are compressed. However, depending on the style and song you’re doing, you may want them buried a little you may not. This isn’t the fine-tuning point; this is getting through the basics of properly multipressing your song.
After you’ve gone through all four compressors, you will see that the dark blue signal in each of the four compressors is the audio after you’ve applied compression. The light blue signal next to it the “before” you applied it. It shows you how you’ve compressed and boosted the original signal. Now tweak the gain make-up higher or lower on each compressor until the dark blue volume level is even across the board. Again, depending on your song style and objective — and what your ears are hearing — you might not want them all even across the board. But start with them all being even. Let that be your starting point, and then do little tweaks from there appropriate for your specific song. Even if you do, for example, bump the lows a little higher in gain because it’s a rock song and you want the lows to be dominant, the differences between each compressor’s volume should not be huge. They should still be somewhat close to being even across the board.
Make sure the overall “Out” level on the far right is not clipping. If you see red, reduce the volume level of the “Out” until the red is gone.
Step 4. Adaptive Limiter: Time to Pump Up the Volume to Professional Grade
The first three steps prepare you for the final magical step that will bring your song to that all-powerful professional grade volume level that has eluded you for so long. The trick is to get to this loud volume level without making the song’s audio sound terrible. The first three steps ensure that when you do pump up the volume on this final step, the end result will be a sparkling, crystal clear track that sounds pristine and powerful across the entire frequency spectrum and sound space. After you’ve added the adaptive limiter to your channel, open it up and configure it as follows:
Set your “Out Ceiling” to -0.1 dB. Peaking begins at zero dB, so this gets you as loud as possible before the music hits the red zone.
Set your “Input Scale” to 0.8 dB.
And, if you really want to pump up the volume, you can then boost the “Gain.” I rarely go above 8.0 dB but technically you can go all the way to 12 dB. Again, this doesn’t mean that the song’s overall volume will be pushed into the red because the out ceiling prevents that. It means there will be less “differential” — i.e. when you see an audio signal drop a little and then shoot back up — a lower differential will mean the overall volume never drops very low. In other words, there is less difference between the quietest point of the audio’s volume and the loudest point; the volume of the entire frequency spectrum stays consistently loud — with the exception of spots in songs where the band lays out and it’s just a quiet piano solo or a singer doing a quiet solo for artistic effect. In commercial music, if you import a Top 40 song from the radio onto your computer, it will look like one solid block form beginning to end because it is consistently loud across the board. Some artists do not like that loudness of commercial music, and they actually prefer a larger differential where there is a more organic, human sounding difference in volumes throughout the song.
And, actually, that whole debate about loudness is kind of a big deal. They call it the “loud wars.” Some artists and labels are revolting against the music industry’s recent tendency to release albums that are incredibly loud across the board.
The signal on the right of the adaptive limiter shows your track after it has been run through the limiter. The signal on your left shows your track before the limiter, so you can see how the limiter is changing your track’s volume.
1,001 Tips on the Internet
To be clear, these are the four pillars of mastering. Whether or not you have Pro Tools or Logic Pro, the workflow is the same: 1) analyze your mixed track to look for any fatal flaws and to see what you’re dealing with; 2) EQ your track; 3) Compress your track; 4) Limit your track and boost volume. I’m sure every engineer and their brother has extra tips and cool little tricks, but your mastering session should always, one way or another, cover these four pillars of song mastering.