Sounds cool. So, ready to talk some shop?
I'll just lay some groundwork first. It'll be like a lecture.
Split-Spectrum Compression
Most of the music I'm working with is made by vibrating membranes — be it a metal string or a vocal chord or a drum head, it's a vibrating membrane of some sort. And a universal characteristic of vibrating membranes is that they vibrate more strongly at some frequency ranges than others and that intensifies as you play louder, which, in effect, means that any instrument you play louder tends to gets more midrangey.
Because the upper harmonics are coming out more?
Just because some frequency ranges are easier to reproduce for a vibrating membrane. You know this intuitively if you play a bass string really lightly. It has this huge, fat sound, but then if you lay into it, it sounds like "clank, clank". When somebody's talking really quietly, you can hear all of these highs and lows, and then if they start yelling, it becomes more midrangey. To some extent, this is present in every instrument. You know how drums being played hard sound when you hear them through a mic? It's always struck me as not quite right. It's not what you want to hear. When things get louder you don't want more midrange, you want more of everything. The idea, therefore, being to compress the midrange frequencies more than you compress the highs and lows so that, as an instrument gets louder, the spectral balance remains pleasing. You can really just divide a lot of instruments into highs and lows then compress the highs one way and the lows another way. It's not always the mids that pop out, sometimes it's the highs and the mids. It's not universal. A typical application is a bass guitar. Every time a player goes up to the high strings, the bottom drops out, and every time they hit the low E, the thing just gets outrageously fat. It's annoying! You can't get a consistent low-end picture. So in my studio I have a crossover, which is like what you'd use for a public address system to separate the lows, mids and highs. I can either use it as a mono three-way or a stereo two-way. So the first thing I do when the bass leaves the tape deck is run it through the crossover, and then I run each of those signals, the highs and the lows, through their own compressor. Then I bring those up on the board so I have a high-end portion and a low-end portion. The advantage of using a crossover is that when they recombine, there's minimal overlap.
You don't have phase problems?
You have less phase problems.
So your crossover is pretty discerning?
I have one that has a pretty high slope≤24 dB per octave, which means that one octave away from the crossover frequency the signal is attenuated by 24 dB In a normal mix this is inaudible. Some times a gentler slope is preferable. I have one of those too. But then you've got to choose the right compressor for the high-end and the low-end. Typically you want different compressors. The one that you're going to compress the low-end with has got to have much slower attack and release characteristics and be something that sounds punchy with low-end. Whereas the one for the high-end wants to have a lot faster response. I like the Urei 1178 for the low-end. But there are many that will work. You've just got to know your collection of compressors to make the right choice. Now let me give you another example of the power of this technique.
You sound like a barker.
(Laughs) It's the gong/kick drum sound, which you get if you put a nice coated Ambassador head on a kick drum, tune it so it rings and maybe play it with a mallet, sort of like a timpani. You know, you're doing a marching band kind of thing where you want a big "BOOM, BOOM, BOOM". But if you just put that in the mix and say, "I want some low-end on that thing," it just goes "wooom, wooom". It just clutters up your mix. So what you do is send it through a crossover. And then, because it's a drum, you gate it so that the high-end portion and the low-end portion have different release times. Then you compress them also, of course, to keep things in control. But you gate the low-end portion with a fast release time so the low-end is now going "wup, wup". But you leave the high-end gate open for a long time, maybe you don't even gate the high-end. Maybe you compress the hell out of it with a really fast-release compressor so that it accentuates the "kaaahhh" sound.
The tail of it?
The tail of it. If the compressor's release is really fast, it goes in and follows the tail down. In doing that you can get all of this personality, which is, in a drum like that, above 500 Hz. The "boom" is down below 200 Hz. I often end up crossing over around 200 Hz. Sometimes what I'll do with a bass guitar is record through an amp that is a little overdriven and fuzzy sounding, without much low-end, and also record a direct signal. Then, instead of taking just one of those and crossing it over, I'll take them both, cross them over at exactly the same point and use just the low-end from the direct signal and just the high-end from the amp. That way, not only do you have individual controls over the lows and highs, but the lows are clean and punchy and the highs are gritty and a little distorted, which makes them more interesting under a lot of conditions.
It gives you a lot more information up there.
