Getting Started – Mic Placement and Levels
Mic placement and levels (or gain) are actually two very different topics – one a little closer to art and the other more like science, but in my mind they go together because they are very important steps that cannot be undone after you’ve recorded, so it’s good to understand them a little before you get started. Also, as we’ll see in a minute, there’s a moment at which the two topics intersect in a way that’s very relevant to home recordings.
We’ll start with levels. When you record with a microphone you’re generally recording three different things: the sound of your instrument; any ambient sound in the room; and the quiet ‘self-noise’ created by the microphone and the preamp and possibly some other gear. In the same way that street traffic will be drowned out if you just play really loud, a good level will give you what is referred to as a good signal-to-noise (s/n) ratio, so that the level of any noise will be negligible compared to the signal from your source.
So what’s a good level? It’s sort of a Goldilocks thing – not too hot and not too cold. If your signal is too hot (high) you’ll clip, or distort, and in digital recording this is something you want to avoid at all costs. Again, this is something you can’t fix once you’ve recorded it. The track in your DAW will likely have a meter on it, and as long as you’re staying in the green section of the meter you’re fine. If a few of your loudest moments go into the orange or yellow section, you should still be fine, but if you go into the red even a little you’ll want to back off of your gain.
When setting your levels you’ll want to play the loudest section of the piece you want to record and see if you peak (go into the red) during that section. Recording flamenco guitar can be especially tricky because golpes and rasgueados can be much louder than, say, an arpeggio section, so you’ll have a wide dynamic range, but you’ll still need to be aware of those loudest moments.
On the other hand, if your signal is too low you’ll have too much of that noise I mentioned a minute ago, because when you turn things up (whether you do this through a compressor, limiter, a gain or normalization plug-in or simply by turning up your volume) you’re turning up everything on the track in equal measure, including that noise you hadn’t realized you were recording.
If your room is loud (stuff coming in from outside, air conditioning, a loud computer fan, noisy neighbors, whatever) the mic placement and level issues overlap for just a moment, because the farther away the mic is from the source (your guitar), the louder you’ll have to crank the gain to get a nice guitar level, and consequently the more ambient sound and self-noise you’ll be recording, too. This is one reason that close mic’ing has come even more into vogue, since so much recording is done in rooms that weren’t necessarily made to be studios, and getting close to the source is one of the easiest (and cheapest) ways to improve your s/n ratio.
One of the things that can be baffling is there are so many places you can turn things up or down in a recording system. To keep it simple I recommend that while tracking (recording) you leave everything at 0db or unity (inside of the DAW this is where they will be until you fiddle with them, so if you’re not familiar with these just leave all faders where they are until after you’ve recorded), and only play with the level on the preamp, which will be the ‘level’ or ‘gain’ setting on the audio interface or USB mic. You’ll adjust this level to get your ‘just right’ level that neither peaks nor is too low.
Here’s an MP3 on which I’ve recorded my voice and a guitar at levels that are too low, too high, then just right. You’ll notice that the volume of each approximately the same, because I’ve matched the output levels inside my DAW after recording. So while the volume is the same, the quality of the recordings is definitely not.
MP3 – Mic Levels
Where to place your mic is incredibly important in getting the right sound, but there are no hard and fast rules – only some conventional wisdom and suggestions. There’s a maxim in audio that says that if it sounds right, it is right, and you’ll want to use your ears to determine what sounds right. Here are a few things to keep in mind:
A good starting position for a microphone in a relatively quiet room is anywhere from 6 inches to 1 foot away from the guitar pointing at the twelfth fret of the guitar. Any closer to the guitar is probably unnecessary. In a studio it is not uncommon to place mic’s much farther away, especially for classical music. Placing the mic farther away will give you more ambient room sound, which can be great in a hall or a purpose-built recording studio, but in most home studios can be very problematic for all sorts of reasons we won’t get into here. Unless you have a great sounding room, I recommend placing the mic not much more than a foot away and adding reverb later if you want it (more room generally produces more reverb, but as the reverb is printed to the track along with the guitar itself, it cannot be changed later if you decided you don’t like it, so I think it’s better to record dry and add reverb later unless the room you’re in has an amazing reverb that you want to capture).
As a rule, you want to avoid placing the mic in front of the sound hole of the guitar. At first it may sound better through your headphones when you do this, but this is generally because we are all susceptible to the fallacy of more volume seeming like better quality. When you place the mic in front of the sound hole you tend to get more of the boomy, bottom end of the guitar and less of the top end, or air. Of course you can EQ later, but it’s very difficult to get rid of that boominess, so I’d say avoid the sound hole for placement.
One of the fun things about recording is that each guitar is unique, as is every player, every room, and every mic, so what works for me with my guitar in my room may not work for you at all. I’ve recorded guitars that sounded best with the mic pointed at the bridge about 3 inches away, though in general I tend to avoid this placement. Some engineers like to point the mic at the 12th fret, but angled towards the sound hole, rather than directly at the fretboard.
In the end, you’ll have to be the judge of what works best for you and you guitars, but to give you an idea I’ve recorded some MP3s of the same guitar and the same mic, but with the mic at various positions on the guitar and at various distances, so you can hear how big a difference these things can make.
Close Placement MP3 – Mic Placement1
Distant Placement MP3 – Mic Placement2
Next week we’ll look at microphones types and some specific models you might want to be familiar with, and look at stereo vs. mono recording.
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