The other kind of space is depth. Stages have the right/left dimensions, but also the front/back dimensions. In an orchestra, the tympani and double-basses are in the back, while the flutes and violins are in the front. How do you create the illusion of depth when mixing a track? Two things: reverb and EQ.
The more reverb you add to something, the further back it appears to be in the mix. Consider the fact that, even in a cavernous gymnasium, if you are right in front of the sound source, you hear very little reverb. Stand at the far end of that cavernous gymnasium with the instrument at the other far end, and you’ll hear tons of reverb. The trick here is that, if you want to put the drums at the back of the stage in your mix, and you put reverb on the kick drum, the bottom end of your mix will often start to smear. The solution is to add reverb to everything except the kick. This also points out another common mistake in mixing - adding too much reverb to a vocal. It gives the effect of the singer being placed at the back of the stage.... or worse, in an entirely different room!
Consider this basic fact of acoustical physics: Low frequency notes have very long sound waves, and high frequencies have very short sound waves. The longer the distance a note has to travel, the more the higher frequencies get lost. So, rolling off the top end of an instrument will help give it the illusion of being farther away. By adding loads of reverb and rolling off lots of the top end, you can make something sound *really* far away! Of course, in mixing, a little goes a long way.
Part 4 - Putting it Together
Before you begin, you have a few goals. First, determine what kind of sound you are looking for in the first place. You might not be able to pick the performer or their instrument, but you can pick microphones and decide where to put them. You also want to consider the question of whether you are recording a singer with a band, or a band with a singer. The answer to this question will determine your approach to mixing, and might even impact your miking choices.
A singer with a band is usually approached from the top down. You dial in the vocal sound, and then bring up the instruments to that place where they play appropriate supporting roles. A band with a singer generally suggests the opposite. You build the band from the bottom up - drums, bass, guitar, etc., and get the band sounding the way you like, and then introduce the vocals to that mix. The question suggests subtlety, but the differences in approach can produce radically different mixes.
You next need to decide which instruments and voices are going to be the “focal points” of the mix, and which others are going to play supporting roles. Remember the “in a room full of giants” quote? Right. Not everyone can be a giant. As a general rule, no matter who you decide gets a supporting role, you will risk getting someone’s nose out of joint. The trick is to carve out spaces for everyone to shine at least here and there, as I have discussed above.
In any case, your goal is to have all parts heard as much as they need to be through a combination of carving out frequencies, and placing each thing in its own right/left “stereo” space, and its own front/rear “depth” space. You will need to make sacrifices and compromises. You will need to take advantage of psycho-acoustic illusions. Just because everything sounds great on their own doesn’t mean everything will sound great together. You will find that sometimes, a part that fits perfectly into your mix really doesn’t sound that good at all when played by itself. That’s okay. It’s not about everyone being a star. It’s about everything working together for a great production, with you being the director.
Part 5: Mastering
Mastering has become one of the most misused words in audio. Back in the day, when songs were cut to vinyl, the music would first be recorded to a tape machine, and then that recording would need to be transferred to a wax cylinder, from which the vinyl records would be manufactured. Mastering was the process of going from the tape to the “master” which was the wax cylinder. In order to do this properly, a few things became part of the process:
ordering the songs - There are lots of things to think about in determining the best order for your LP.
getting a consistent tone from one song to the next. This is done with EQ.
tops and tails - Beginnings and endings are edited and faded out so that they flow naturally and sound “right.”
compression - It was often found that the cutting needle in the wax cylinder was literally bounced out of the wax, thereby ruining the cutting process, whenever sudden transients (say, a sudden snare pop, or a cymbal crash, or an extra hard jab on the bass) occurred. In order to tame these so that the cutter wouldn’t jump out, they used compression.
Nowadays, the word “mastering” is often used as a generic term for compressing the daylights out of a track to make it as loud as other loud-as-bombs commercial recordings. Whatever floats your boat, or suits your purposes, I suppose. We’ll save the “volume wars” discussion for another time, but in short, if you listen to an album from the 1970’s and an album from the 2000’s, you’ll find that the modern record is very, very loud (for many people and purposes, there is a rough equation that suggests “louder=better” compared to the classic album. You’ll also find that the classic one has MUCH more dynamic range. Why? Compression.
Compression basically takes the loudest parts of your mix and the quietest parts of your mix and brings them closer together. The best way to visualize that is this: If you play a classic album from the ‘60’s or ‘70’s, and watch the meters on your audio system, they will bounce up and down along most of the entire length of the meter along with the music. The quiet parts are quiet and the louder parts are louder. If you look at a wave form of a classic recording, you see obvious mountains and valleys. If you play a modern recording and watch the meters, they will basically just flicker right around the maximum level before it distorts. The loud parts are loud, and the quiet parts are... well... damned near as loud as the loud parts. If you look at a wave form of a modern song, it looks somewhere between a fuzzy caterpillar and a big long brick.
It’s a trade-off. Louder songs on the radio or wherever get the listeners’ attention and sell more records. People like to play their music loud, and the louder the play it, the more their bass slams and their highs soar. Recordings where the dynamic range is preserved sound more natural, and usually have a lot more “punch” to them. Take an older recording and turn up the volume so that it seems as loud as the newer recording, and many people will say that the older one now actually sounds much better than the newer one.
One artefact of compression is that it does seem to “level out” the mix a little more. Because those quieter parts do, indeed, seem louder than they did before compressing the mix, those little things like reverbs, delays, and subtle things almost buried in the mix become more evident. This can be both a blessing and a curse. On the other hand, not compressing a mix leaves many listeners feeling like they are listening to an inferior product because it isn’t as loud as their other songs. Balancing the two worlds can be very tricky.
It is almost impossible to tell someone how to EQ a guitar or what the best compression settings are for a snare drum because there are so many variables that any answer would be considered a vague ballpark at best. I’ve also skipped over a number of technical things: microphone polar patterns, limiting, side-chaining, the difference between inserts and aux buses, the difference between time-based effects and modulation effects, what the difference is between phase and polarity, why you really DO need proper monitors and not stereo speakers, and all sorts of other things. My hope is that, with what I have written about, that no matter what your tools, and no matter what your effects, you’ll be able to approach a mix with a practical way of looking at things and for helping each part to find its own place in the space you are creating. In the end, whatever sounds good, IS good. If you don’t get it good from the beginning, damage control is a frustrating inevitability. If you get it good from the beginning, you can easily help it along and things will almost seem to mix themselves.