Why use two when one will do?
Technical Articles/July 28, 2014
Sure, there are times when two mics are better than one. Just look at the US President every time he speaks. There are always two SM57s on his podium. But in reality, only one of these is being broadcast at any given time. The other is primarily there as a redundancy measure.
When it comes to recording and mixing, however, two mics aren’t always the solution. Although a redundancy backup is a good idea in some circumstances, one mic will suffice in many recording situations.
Since the invention of multitrack DAWs with virtually limitless track counts, many of us have developed a lazy, ill-conceived approach to recording. We record huge numbers of audio tracks, sometimes with little understanding of how this later impacts the mixing process. We build up massive song files that choke our computers’ capacity, and yet sometimes capture very little in the way of finely crafted sounds.
It’s a form of ‘musical inflation’ if you like, where two mics have become the modern equivalent of one, and four the equivalent of a stereo pair, and where the person with the most (rather than the best sounding individual) channels wins. The problem has become so endemic in fact that, for some engineers, a sound simply hasn’t been recorded properly if there aren’t two, three or four channels accounting for every single sound in the session file:
“Yeah, what’s cool about this incidental shaker track is that I recorded it with three mics, and what’s cool about that is that there are three audio files… You can mix it anyway you like!”
What’s wrong with this picture? Well, it’s simple really.
The notion that three recordings of one sound via three mics is always better is flawed thinking (even if it’s not obvious to the engineer at the time). It’s like providing three answers to a trigonometry question and assuming that one of them will always be right.
While there are many good reasons to use multiple mics on a recording, there are countless times when one mic offers a superior outcome for numerous technical, musical and financial reasons. Knowing which technique to choose is sometimes called – in audio parlance – engineering.
IT MUST SOUND GOOD!
The ‘scattergun’ approach – where an engineer fires several mics at the target hoping one will hit the bullseye – fails as often as it succeeds, for several reasons. Firstly, it requires the engineer to focus intently on multiple sounds, multiple recording chains and multiple files at once, rather than one. This rarely results in as much care being taken with any of these mic placements or gain structures as there would have been with just one. It also takes more time and involves more equipment. More insidiously, it also sets up a false dialogue inside the engineer’s head that says: ‘somewhere in amongst all of these recorded tracks there’s at least one channel that sounds half decent’.
Sometimes three recordings leave you with nought but a pile of shite.
The other problem with this approach occurs later if the session is handed over to a mix engineer. In this situation, documentation is rarely provided which clearly explains how each mic has been recorded, or whether or not the mics were recorded specifically to provide a mix engineer with several mono options (in which case one can be selected and the others confidently ditched), or one grandiose stereo image replete with room ambience. If it’s unclear what’s what, hours and even days can be clocked up trying to decipher it all.
THREE FOR THE PRICE OF NONE
Then there’s the other common falsehood perpetrated on countless innocent recordings – that two or three mic channels will always collectively sound better than one, even if you might only score each of the individual recordings a 5, a 3 and a 2 out of 10. Three mics placed badly in front of an instrument never add up to a perfect score… ever! Combined, they may add up to a total score of about three, not 10… an ‘F’ in anyone’s book.
IT’S ABOUT SUBTRACTION, NOT ADDITION
And the common reason for this failure is simple – phase. I’ve said it before and I’ll no doubt say it again: bad phase management is the death of any potentially good recording or mix.
It can rear its ugly head in several other ways that we won’t go into here, but where two or more similarly placed mics (and sometimes D.I.s) are collectively used to capture a single sound source, their combined tonal balance can wind up sounding vastly inferior to any of the individual components.
Like a crown of thorns starfish at a coral reef convention, phase can gnaw away at the power of your sound ’til all you’re left with is an emaciated, comb-filtered facsimile of the original.
MONO IN, STEREO OUT
The solution to all of this is simple: if you’re recording something, record it with a single mic whenever possible. Take care to choose the right mic for each occasion, as well as the right preamp and compressor etc, and your recordings will sound far superior to phasey, comb-filtered multi-mic’d equivalents. With only one mic in the room, phase issues are extinguished.
The other widely ignored problem here is that, in stark economic terms, literally thousands of dollars can be wasted over the course of some of these sessions: more time spent setting up, more time spent recording, more money spent hiring unnecessary equipment, more time transferring files, more time organising mix prep, and more time during mixdown spent determining what’s relevant and what’s not.
The point of this article isn’t to insist that multiple-mic techniques are always invalid – obviously I don’t want anyone to walk away thinking that. I’m simply trying to make the point that being aware of bad habits and thinking your way out of them ultimately makes you a better engineer, and one of the most endemic of these is currently the overuse of lazy two, three and four-mic recording setups.