The Recording Guitarist: Two Mics Are (Sometimes) Better than One
This month we’ll see how blending sound from two mics can add color and distinction to an electric guitar recording—or ruin it.
But first, a few clips inspired by reader comments. I recorded last month’s audio examples with the mic’s element aimed directly at the grille, just at varying positions on the near/far and center/edge axes. But several folks mentioned orienting the mic at a bias—say, at a 45 degree angle relative to the grille. How does that alter the tone?
Hear for yourself: I recorded an audio clip four ways (Pic. 1) through a Shure SM57.A. Center position, 1" from grille
B. Center position, 45 degree angle, 1" from grille
C. Midway to speaker edge, 1" from grille
D. Midway to speaker edge, 3" from grille
No surprise that clip B sounds darker than clip A—the element points away from the bright speaker center. Now compare clip B to clip C, where the element is aimed to the same spot, but with its barrel perpendicular to the grille. Clip C has a touch more low-end warmth. That’s the proximity effect—the mic’s tendency to pump up lows when positioned close. The mic is a couple of inches further from the grille in clip D, nixing some of the proximity effect and producing something quite similar to clip B.
Angling a close mic in relation to the grille slightly lessens the proximity effect, which sometimes yields clearer tones.
Key point: Angling the mic reduces proximity effect. (It probably makes total geometric sense if, unlike me, you know your ass from your hypotenuse.) The technique is especially useful for minimizing leakage on live stages or when tracking multiple instruments.
The birth of big. There’s a great illicitly circulated Led Zeppelin studio outtake (sadly not on the official Outtakes collection). While Jimmy Page plays the “Heartbreaker” solo, we hear an engineer bringing up two mics. First is a close mic, dry and claustrophobic. Then we hear a spooky, resonant room mic. Then we hear the two together, slightly panned in stereo. It’s like witnessing the birth of modern rock guitar tone, but without messy placentas and stuff.
Exploitation of ambient space is a big part of Zeppelin’s magic. Jimmy Page realized that the emotional impact of a riff wasn’t merely about the player’s notes and guitar tone—space itself could impart majesty and mystery.
But before you set up 47 mics, consider this: Each new mic adds something, but takes something else away.
Positioning a second mic at varying distances from a close mic emphasizes different frequencies while attenuating others.
Double trouble. Whenever you blend mics, phasing comes into play, because the sound reaches each mic at a slightly different time (see Pic. 2). Like a phase shifter pedal, which combines your dry signal with a slightly delayed signal, some frequencies resonate more strongly while others are cancelled. The result can add cool texture and dimension, or just make parts sound thin and diffuse.
I recorded a quick clean-toned example with the SM57 right on the speaker, with a Neumann TLM 103 condenser alongside, and then at increasing distances from the amp. In the audio clips, you hear the 57 alone for six seconds before the 103 switches on. It’s dramatic!
Which sounds best? To my ear, none of the blends sound as good as a single close mic. My vintage Strat tone is already “phasy” sounding. The cancelled frequencies overemphasize this quality, while the added ones just sound sloppy.
It’s tricky to predict the results of mic blends—you must experiment. For that reason, engineers often record via several mics, but wait till the mix to decide which sources to use. Yet the technique can be more than hit-and-miss. For example, I got to visit Metallica in the studio when they were tracking the “Black Album.” Producer Bob Rock had erected a low tunnel of drop cloths extending many feet in front of one of James Hetfield’s amps. He explained that the tunnel was tuned to emphasize “one particularly prominent frequency” in James’s tone. (Bob clammed up real fast when I asked which frequency, but I assume he referred to either the 77.8 Hz of James’s low Eb, or 139 Hz an octave above.)
Rate your room. Evaluate the sound of your room before laboring to capture it. Hetfield and Rock were working in a fine studio. Pagey recorded in spacious rooms and spooky old castles. But if you’re working in a crappy-sounding bedroom or garage, your best bet may be to close-mic and add artificial ambience later.
But before surrendering to an uninspiring room, search for its hidden sweet spots. Have a friend play your guitar (or ReAmp one of your parts) as you wander around, listening for lively spots. Get down on all fours. Crawl around. Bark like a dog. (Well, the barking might not help.) You may be shocked by how much better certain spots sound.
A bathroom’s reflective surfaces can lends a bright, aggressive edge to rock tracks.
Toilet tone. You may already have a great guitar chamber: your bathroom. Reflective porcelain and tile can add a tough, resonant edge, especially to rough-hewn rock parts.
I recorded another set of two-mic tones, close-miking a Marshall 18-watt clone in the shower with a Royer R-121 ribbon mic, adding the 103 condenser at varying distances (Pic 3). Here I feel the second mic does improve things, adding texture and depth to a potentially generic crunch tone. (The clips feature the close mic, then the far mic, and then both.)
All clips so far feature roughly equal mono blends. Adjusting relative levels, panning positions, and dynamic processing adds infinitely more wrinkles. I recorded a few more variations: In clip A, the panning morphs from mono to maximum stereo back to a modest spread. (Does one particular position sound best?) In clip B I apply extreme compression to the room mic, a common technique. And for clip C, the condenser mic is behind the open-backed amp. (This thumping tone can bulk up a track, though you usually need to reverse the phase of one track when mics face each other.)
In short, multiple mics can summon magic or misery. So let’s hear about your magical/miserable recording experiences!