Subtractive Mixing — Less Can Be More

In the world of digital mixing, there’s an inescapable fact: you have an absolute fixed amount of headroom. When you hit 0dB Full Scale (FS), you’re out of bits. So what happens if you ignore this fact? Simply put, adhering to (or failing to adhere to) this set-in-stone precept will make or break your mix. So how do you manage headroom while you’re mixing? After all, every track in your project is fighting for space. Every time you push up a fader or boost a frequency on your EQ, you are eating into your headroom. The solution? Instead of pushing a fader up to make a track louder, pull others down to reveal that track. Instead of boosting desired frequencies with an EQ, cut undesirable frequencies to make the desired ones more apparent. And since every track is fighting to exhaust your mix’s headroom, prioritize each element of your arrangement and reassess its importance.
Headroom? What Is It, Really?
So what is headroom anyway? Great question! Simply put, it means the difference between your track’s highest peak and 0dBFS (dB Full Scale). Exceeding 0dBFS means clipping, which means nasty-sounding digital distortion. Your mileage may vary, but I personally like to start a mix with all my tracks at a consistent level — an average (RMS) level of around -18dB works great. This is a conservative setting and will ensure that your peaks never stray beyond 0dBFS, even after piling on plug-ins.
Get Your Priorities Straight
Inexperienced mix engineers often hit a common stumbling block — they want to make a track louder, but they run out of headroom. There’s no space left in their mix! So what are your options? Well, there are two ways to make a track louder: you can either turn it up, or you can turn something else down. If you’re low on headroom, the first option is a surefire path to an inferior mix. The second option, on the other hand, is an effective way to resolve battles between tracks that are competing for the same sonic space.
It’s important that you decide which elements will be the focus of your mix. Then take the other elements that occupy the same frequency and spatial bandwidth and move them out of the way, either by lowering their volume, panning them, or EQing them. But what you don’t want to do is increase the volume of the primary element.
Pro Tip: Every DAW worth its salt includes basic metering. If you want to dive in deeper, plug-ins like Waves WLM Plus, Blue Cat Audio DP Meter Pro, and iZotope Insight 2 Essential are a worthwhile investment.

“People are going deaf because music is played louder and louder, but because they’re going deaf, it has to be played louder still.” — Milan Kundera

Carving Out Space for Your Tracks
EQing is an important part of mixing. It’s how you carve out space for your tracks. But be careful — you can do a lot of damage with an equalizer! It’s natural to want to boost a frequency in order to hear more of what you want. Kick drum not thumping? Boost the lows. Vocals not cutting through? Crank the mids. Cymbals sounding a bit dull? Turn up the highs. Right? Wrong! Thanks to a phenomenon called frequency masking, you may not need to boost anything at all. Rather, the same frequencies on other tracks may be concealing the frequencies on the track you’re trying to highlight. Cutting these frequencies on other instruments will make space and may be all you need to do to make your track pop out of the mix.
Lows and low-mids are common masking frequencies — they create mud. That’s when a highpass filter becomes your best friend. By cutting the ultra-low end (100Hz and below) on everything except your kick and bass, you can open up a lot of space right from the get-go. As for the low-mids, grab an EQ plug-in like FabFilter Pro-Q. Instantiate it on any track that sounds dull or muddy, create a massive boost in the 250Hz–500Hz area, and then sweep it around until you find the most offensive frequency. Turn the boost into a -2dB cut. Then slowly increase the cut as needed. You’ll be surprised at how much you can increase a track’s clarity by doing this — no boosting required!
Pro Tip: It’s very common for tracks with similar frequencies to mask each other. iZotope Neutron‘s Masking Meter is a great way to uncover the offending frequencies.
Discard What Is Useless
Renowned kung fu master Bruce Lee taught his students to “discard what is useless.” You can apply this same philosophy to your mixes. Not every song calls for an everything-including-the-kitchen-sink arrangement — more is not always better. Ask yourself: does your project really need 24 tracks of guitars? Is the synth pad adding anything meaningful to the arrangement? Are the song’s core elements being overshadowed by the 5-piece horn section?
If you’re having difficulty making an element fit into your mix or think it’s concealing more important elements, ask yourself, “Does this really need to be here?” When you mute the track, does it sound like something is missing? Does the mix sound better without it? Once, while I was mixing an industrial metal song, I realized that the high-gain rhythm guitar part served no purpose other than to mask the distorted synth elements that were actually driving the song. My reaction? I discarded what was useless — I muted the guitar. And the final mix sounded all the better for it.

“Absorb what is useful, discard what is useless, and add what is specifically your own.” — Bruce Lee

Conclusion
This article merely touches on the intricacies of mixing — the information presented here is very generalized. And workflows vary from engineer to engineer. If you have questions about how to mix your music, need advice on which EQ plug-in is best for you, or want help with anything else related to audio production, give your Sales Engineer a call at (800) 222-4700. They’ll be more than happy to give you some pointers.
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