Before You Record:
There are many ingredients to a good mix. The sound of the final product is influenced by everything that produces the sound from the very beginning. Consider:
The sound of the instruments themselves - You wouldn’t pick an Ibanez guitar through a Triple Rectifier for your country band. You wouldn’t pick a Telecaster and a Twin Reverb for your metal project. An entry-level guitar through a cheap practice amp will not sound as good as a well-appointed guitar rig. A drum kit that is not properly tuned or a singer who squeaks notes out from their pinched little throat cannot be fixed by a great mix engineer. The basic rule of recording is “crap in = crap out.”
Mic choice and mic placement - Mics have different designs and utilize different technologies. Some are accurate. Some have character. Some are bright. Some are warm. Some are designed to bring out the depth of a kick drum from up close while also accentuating the click of the beater, while others are designed to capture the subtle nuances of instruments from a distance.
The recording environment: Some rooms sound spacious. Some sound dry. You know that hollow, boxy sound from your video camera when you recorded your friend singing in your basement? You can’t EQ that out.
The performance itself: A great mix of a crappy performance still sounds crappy. A mediocre mix of a great performance will still sound pretty good.
So, before you have even hit the “record” button, a lot of the sound of your mix is pre-determined by these factors. Great musicians will give great performances and have great tones. A great studio will have great rooms. A great producer will know which microphones to use, where to put them, and how to use the preamps to help get the best possible tone from the microphones.
Okay... now MIX! -
Part 1 - What’s the Frequency, Kenneth?
The human ear is designed to hear frequencies from 20hz (vibrations per second) to 20 000hz (also known as 20khz.) A veeery low bass rumble from a kicker box in the Honda Civic that goes booming past your house might be in the range of about 40hz. The mosquito buzzing around your ear clocks in closer to 16khz. We call these low and high frequencies.
Each instrument has a fundamental (the main pitch the note is playing), and then the overtones that help to shape the timbre and character of the note, which occur at much higher frequencies. The open E string on a bass guitar is about 40hz. If you had a pure tone at 40hz, it would not sound like a bass. If you wanted to bring out the attack of the note, you would have to boost frequencies around 2khz. Although the note that is being played is at a very low frequency, the “pluck” of the note is much higher. If you want to make the bass guitar “stick out” more in the mix, it is not necessarily about boosting the bottom frequencies where the fundamentals are. You could bring out the attack of the notes instead, making the bass much more noticeable.
Imagine an orchestra. You have a wide range of instruments that, cumulatively, take up an enormous frequency range. The double-basses, the tuba and the tympani occupy the bottom; the piccolos, cornets and chimes occupy the very top, and the other instruments occupy various ranges within the middle. Now, imagine the basses and tubas only. Now throw in a bassoon playing in its low register. How well do you think you would hear it? Obviously, not very well. It is competing with that low frequency space with two other instruments. Have it play an octave higher, and it will be much easier to pick out, as it would have more of its own “space” to occupy where there is less “competition.”
The same thing happens in a mix. If you want to bring out the “whoomp” of a kick drum by boosting the EQ at 40hz, and the “thud” of the bass by boosting the EQ at 40hz, you’ve got two things competing for that same frequency space. A better solution would be to bring out the “thud” of the bass by boosting the EQ at 40hz, but then cutting out some of the 40hz of the kick drum, giving the bass more room to exist down there. But what about the kick drum? Boost instead, the click of the beater, which lives somewhere around 2khz. There is no “competition” from the bass guitar there, and each instrument now has its own space in the frequency spectrum. The bass is no longer hiding behind the kick drum, or vice-versa. Both instruments can now be heard clearly. There will also be a bit of an “auditory illusion” at work where, even though you are boosting the click of the beater on the kick drum, the listeners will actually attend more to the lower frequency (the fundamental) of the kick drum, and hear it too... or at least they’ll think they will.
Use the same approach to “notch out” places for other instruments to exist within the frequency spectrum by cutting some of the top end from the guitars to make room for the vocals, or rolling the bottom off the guitars so that they don’t compete with the bass.
Part 2 - Louder than bombs
Imagine you’re downtown Manhattan, surrounded by a huge density of very tall buildings. Which one is the tallest? Well, it can be hard to say. From where you’re standing, they’re all pretty darn tall. In fact, with that many of them at the height they are, does it really matter which one is tallest? In a room full of giants, none of them look especially large. Now, take one of those buildings and put it in a small town. All of a sudden, that one building stands out like crazy. It’s monstrous! That’s right. Everything is relative. Not everything can be louder than everything else. We judge volume in a mix not on its own merits, but by comparing it to the other elements in the mix. If one thing is going to be very big, then you need to have things around it that are comparatively very small.
Imagine a metal band. The drummer wants big, huge, crashing drums. The guitarist wants a wall of massive guitars. The bass player wants to rock the house with his crushing rhythm. The singer just wants to be heard. Everyone says, “turn me up.” Obviously this won’t work. If you listen to most metal recordings with those huge walls of guitars, you might be surprised when you *really* listen, that the drums and bass aren’t nearly as loud as you thought they were.
Why not? Answer = arrangement. That big wall of guitars isn’t ear-assaultingly loud all the time. If they were, they would lose their effect... like that one teacher we all had who did nothing but yell all the time. After a while, it just becomes part of the landscape and you stop noticing. Placed beside themselves, they want “periods of smallness” too, in order to make those huge moments still seem huge. So, when those guitars are getting small for a bit, there is a perfect opportunity to ramp up those toms and put in a nice bass run to not only remind the listener that the drums and bass are still there, but to impose a sense of how big they are. The listener focuses on that big drum sound and the fat bass while the guitars are laying low, and then when the wall of guitars comes in, they sound huge again. The listener just doesn’t notice (until he/she is trained to notice), that the drums and bass are now comparatively small again.
Part 3 - Space
The first of two types of space is the stereo field. You have the right-left space represented by the right and left speakers. We’ve all heard the fighter jet in the movies that you hear in one speaker and then seems to fly over to the other speaker before finally fading off into the distance. This is the stereo field. If you imagine a live performance, you would traditionally have the musicians arranged on the stage in a way that makes sense for the musical presentation. Often, we mix with that in mind. Placing the lead singer in the left speaker would be just as strange as having the lead singer standing near the stage entrance by the curtain to sing while the rest of the band played on stage.
Another way of giving instruments their own space is to separate them not only by frequency space, but by stereo space. Imagine two guitar players on a stage, each with their amps stacked on top of each other. It wouldn’t surprise you to find it difficult to tell which guitarist is playing which notes. In fact, it might likely just sound like one guitar playing a jumble of notes. But if you took one guitarist and had his amp on the left side of the stage, and the other guitarist and put her amp on the other side of the stage, it becomes much more obvious which guitarist is doing what. The sounds still blend, but the effect of them being two independent parts is made much more distinct. Because guitars and keyboards are often competing for frequency space with lead vocals, by moving those parts a little further right and left, while keeping the singer in the center, allows each instrument to have it’s own stereo space, with no competition from the other parts within that right-left spectrum.