Here’s a concise (hopefully) exploration of what I listen for while I’m mixing. I say exploration because I’ve realized there are a lot of things that I do in my mixes just because I like the way they sound, but I’ve never really thought about why, so my goal in this is to be able to explain not only what I do, but when/why I do it so that it can apply to your mixes as well.
And…I just added “Part 1” to the title. I’m not even through with the introduction and I’m already deciding there’s going to be a part 2. I lied, this won’t be concise. Not at all.
First, different frequency ranges:
Music is just a bunch of frequencies coming together in a way that’s pleasing to our ear. So what makes some frequencies desirable and others not? Why is there such a thing as an equalizer? Let’s begin our exploration shall we?
I break frequencies down in to five ranges, you’ve probably heard them before: Low, Low-Mid, Mid, High-Mid, and High frequencies. For the sake of this article, lets define those ranges: Bass will be 20hz to 200hz, Low Mid are 200hz to 600hz, Mids are from 600hz to 3kHz, High Mids are 3k to 7k and Highs are 7k to 20k.
You’ll notice there are a lot of mids in there. That’s not by accident. The midrange is where human hearing is most sensitive and accurate and is most able to tell changes in frequency. So because of that, we have lots of names to describe this range.
Let’s start with the low end. This is the foundation of your mix. It’s the “oomf” that makes the subs shake and lets people know that the Holy Spirit is in the room! It’s also one of the trickier ranges to control because there’s a lot of sound energy in this range. Since sound is vibration, you’ve probably guessed by now that the low end can create very powerful vibrations (like what shakes your chest from the subs) and while that power is important to make your mix sound full, thick, and heavy, it can also easily overpower a mix if it’s allowed to run wild (I know, I know…#CrankThatBass). For this reason, I tend to insert a high pass filter on the majority of my tracks that I suspect contain unnecessary bass information. Things like acoustic and electric guitars, vocals, snare drums, and basically anything that isn’t a “bass instrument” like a kick drum, bass guitar, or a low pad/keys part. I do this to prevent the buildup of unnecessary bass frequencies that could contribute to the low end overpowering a mix. I think the most important word to remember when listening to the bass is “balance”. The bass, as booming as you might want it, must be proportionate to the other frequencies. It can still boom, but it can’t overpower.
Next, Low Mids. This is one of my favorite frequency ranges to talk about because so many people go around scooping out low mids because somebody told them that 250hz was designed by the devil himself trying to make their mix muddy…..and then they proceed to drain all the warmth out of their mix. Yes, the low mids can be muddy. They can also be warm. The word I think about for low mids is “control”. Control in the level, control in the dynamics, and control in the tone and resonance. Additionally, the low mids are what tend to balance out the other sections midrange and like we talked about before, the midrange is the area our ears are most sensitive to, so without a balanced amount of low mids, other frequencies can start to feel overly abrasive when you turn the mix up.
Third, Mids. This section of the midrange is where a lot of the fundamental clarity of your melodic instruments come from. It’s also a range with many distinct tones within it. For example, the “honk” of certain instruments comes in around 600hz-800hz, paper-y sounds come in around 800hz-1k, 1k to 2.5k has got what I affectionately refer to as the “walkie talkie” frequency. Along side that and extending slightly above is the “tinny” sound that some instruments can have. All of those descriptions sound rather negative, and they are, but that’s because the human ear tends to notice a given frequency when it’s too loud to where it becomes abrasive (and therefore painfully obvious) so we’ve adopted these descriptors, but conversely, a lack of these frequencies won’t sound right either. As I said earlier, it’s where a lot of the clarity and definition are and for that reason they are vitally important to a good mix. I thought for quite a while on what word I’d associate with the midrange, but after thinking about it, I’m going to go with “flavor”. To me, this has two meanings: first, it describes the variety of timbres that are available in this range, second, it reminds us that even within this particular frequency range, one flavor, or frequency, can easily overpower the others and a midrange that is in poor taste. (See what I did there? punny, right?)
Next are the High Mids. I’m going to go ahead and give you the word association right here because it’s pretty obvious: moderation. This is the frequency range that the human ear is most sensitive to, and thus, is a range that can easily fatigue the ear if there’s too much of it. Now, go Google “Fletcher Munson Curve”…yeah, right now. It’s really important. I’ll wait, I promise. Ok, did you see that? It’s a graph explaining how much sound energy it takes for humans to perceive frequencies at “equal loudness”. What the heck does that mean? Well, it basically answers the question “If I have a sine wave at 100hz coming out of one speaker, and a sine wave at 2.5khz coming out of another speaker, how loud would I have to turn one of those signals to make it sound the same volume as the other?” Somewhat surprisingly (or perhaps not if you Googled what I told you to) it’s not going to be the same volume for both signals. You’ll actually have to turn the bass signal up significantly more than the high signal to make it sound the same. Why is this? It’s because our ears perceive some frequencies more easily than others. Specifically, it takes a lot of low end for us to be able to hear it, then progressively, we hear the frequencies more and more easily until finally we reach our most sensitive spot: the upper midrange. Scientifically, this is because our ear canal resonates at around 2.5k to 6k and sort of acts as a natural amplifier for those frequencies. See, science can make you mix better! Isn’t that cool? Armed with this new-found information, you can now understand why we are most sensitive to this range and why it leads to fatigue and why it must be used in moderation. If you solo electric guitar, or a voice or, a snare drum and start to eq it, adding a good bit of these upper mids may sound pretty appealing. It causes the element to come forward in the mix, there’s more presence, and it just sounds….better. Then…you un-solo everything. And your mix rips your head off and you die in agony and the last sound you hear is the abrasive harshness searing your eardrums. Ok…I exaggerate. Point being, this is actually a frequency range that can sound very good and is vitally important in creating a mix with good presence and punch, but it’s also probably the easiest frequency range to overdo, and the buildup of frequencies across this range will creep up on you until you’re left with a harsh, fizzy, and abrasive mix. Use it in moderation and you can bring elements forward and add presence, abuse it and you’ll hurt people. It’s that simple, and that complicated.
Alright, last one: Highs. This range is tricky; it’s not quite as dangerous on the ears as the high mids, but there’s still an element of risk if this range is overused. Too much and you’ll run in to tasty things like sibilance (around 6-8k) and brittleness (around 8-16k) above that, it’s almost frequencies that are felt rather than heard. The easiest way to figure out what those high frequencies are like is to insert a low pass filter and cut some of them out and note which sounds and timbres go away. Breathiness in vocals is located here, as is the snap of the snare. Much like the low frequencies, these can build up across a mix, so a lot of times I’ll choose to put a gentle low pass filter across some of the elements that just don’t need to be up that high (especially in close mic’d drums to eliminate some of the tones of the cymbals that may bleed in). My word association for this range is “Contrast”. In this context, contrast refers to the difference the high end can make in whether the sound appears bight or dark (aka dull) and also to how useful this range is in creating differences between elements in the mix. Some elements are lighter, some are darker, but they all create an overall sense of depth, space, and movement in a mix.
Alright, that wasn’t concise at all. I’m sure part two will be even longer. In that, I’ll talk about how a mix can come together across three dimensions: High to Low (achieved through different frequencies) Left to Right (achieved through panning and phase) and Front To Back (Achieved via volume, effects, and frequency)
Until then, here’s a recap on the word associations:
Low = Balance
Low Mid = Control
Mid = Flavor
High Mid = Moderation
High = Contrast
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