Vital tips to make your recorded guitar come alive using the right microphones and techniques
Unlike recording electric guitar, where the focus is on capturing your amp's tone, with acoustic guitar, the instrument itself is far more critical in the process. The tone that comes off your guitar's soundboard and reverberating in the air is what you're after. Read on for essential advice on how to capture that sound with all its subtleties.
Is your guitar ready to record?
First things first. Put on a new set of strings in advance, allowing time for them to stretch before your session. Make sure your guitar is set up well with no buzzes, rattles or dead spots on the fingerboard. Tuning and fret-to-fret intonation should be spot-on. An acoustic guitar that's not ready to record can't be fixed in the mixing or mastering stages. If in doubt about what your guitar needs in order to be at its best, take it to a guitar tech for a professional assessment and setup.
While dynamic mics are dandy for recording electric guitar cabinets, they generally don't do so well with acoustics. In order to capture an acoustic guitar's complex harmonics, subtle overtones and wide frequency range, especially in the upper registers, a condenser microphone usually serves best.
You can dig into the details of how condenser microphones work with our Microphone Buying Guide. But for now, suffice it to say they are the first choice for recording acoustic guitars in most studios.
Choosing the diaphragm type
Condenser mics come in two flavors: small diaphragm and large diaphragm. Each has its advantages and disadvantages when recording acoustics. Small diaphragm mics react to high-frequency transients faster, resulting in a crisp, bright and articulate sound. They're often are a good choice when you want to hear a lot of detailed string-to-string definition. Think fingerpicking or flamenco guitar.
With their greater mass, large-diaphragm condenser mics typically impart a warmer, more rounded sound. They excel at handling harmonically dense rhythmic strumming. Depending on your recording space and guitar, sometimes using both types of condensers may make sense in order to bring out the guitar's entire range. By recording with the two different mic types, you'll have more choices when it comes to mixing a well-balanced sound.
Picking a polar pattern
As detailed in our Mic Buying Guide, the polar pattern of the mic—the area it picks up sound from—is also an important factor. The most common polar patterns used to record guitar are cardioid and omnidirectional. Cardioid mics pick up sounds in a heart-shaped pattern from the front of the microphone. This can be good when trying to record in spaces lacking optimum acoustics, and in those situations where you want to get up close and personal with the output of the guitar without a lot of ambient sound.
By adding more "air"—more atmosphere—to your recordings, an omnidirectional mic can produce a more natural-sounding recording that "breathes". Keep in mind, just as a cardiod pattern is ideal for dealing with less than optimal acoustic spaces, an omnidirectional microphone will truly reflect what your room sounds like, warts and all. Some mics have switchable polar patterns making them more versatile. Choosing a model with multiple polar patterns can make a lot of sense for musicians with tight home-recording budgets.
A sizable book could be written on the art and science of positioning microphones for best source capture. And, of course, the internet abounds with demos and theories about where to place your microphones. But we'll keep it brief. The key is to experiment.
Every recording space is different, every guitar is different, players and their tastes vary wildly. First, learn to listen critically and objectively to the sound your guitar makes. Then do the same with your recording. How closely does it match your guitar's actual sound? Are the dynamics right? Can you hear all the nuances that matter?
Keeping a few principles in mind will help you get to a good sound more easily. The sound your guitar projects varies somewhat along its length. Usually the most balanced mix of low, mid and high frequencies are found in the bridge area—a logical spot to position a mic . But because it's easy to accidentally hit the mic when it's positioned close to the soundboard, they are often placed a little below the bridge and tilted up. Sometimes positioning the mic a little above the bridge and tilting the mic down results in a more pleasing sound. A distance of about seven to twelve inches from the guitar top often yields the best recorded sound. Again, be sure to experiment keeping your ears wide open while you reposition the mic(s).
The Electro-Voice ND66 Cardioid Condenser Instrument Microphone features a locking rotating head, which is great for getting a variety of unique and difficult microphone placements.
If you're seeking big, robust bass notes or powerful chords, try positioning a mic near the soundhole—it usually projects the greatest low-frequency output. Move the mic in and out to find the sweet spot frequency-wise by taking advantage of the proximity effect. Conversely, if you're looking for a tighter, drier, or more percussive sound, try positioning the mic near the fingerboard—somewhere between the 13th and 19th frets.
If you opt to use two mics, be aware of potential phase problems—a phenomenon caused when sounds reach the mics at different times. Placing mics at an equal distance from the sounhole can help as will flipping the phase switch on one mic in your hardware mixer or recording software. If your mics sound notably better when you listen to each in isolation of the other, you likely have a phase problem.
Want to learn more about recording? Check out our extensive selection of books, DVDs and more.
Mixing for acoustic guitar made simple
Well, maybe not that simple. Like miking techniques, the subject of audio mixing is a near endless topic and It's not our intent here to give you a complete grounding in the subject. But keep the following mixing techniques in mind and you'll be onboard to give your acoustic guitar tracks the luster they deserve.
Control the dynamics with compression
As with mic positioning, experimentation is essential when it comes to applying compression. If the acoustic guitar serves as the main rhythmic and melodic focus of the recording, a modest amount of compression can help it sit more comfortably in the mix.
Try dialing in compression ratios between 3:1 and 8:1 as a starting point. Then tweak thresholds so only the loudest peaks are reined in—usually around 5 - 6dB, depending on the overall volume of your track. If you want the guitar to recede more into the mix, select faster attack times. To focus on the more percussive aspects of the performance or bring out pick attack, choose a slower attack setting.
The Waves API 2500 Compressor is a versatile dynamics processor that lets you shape the punch and tone of mixes with absolute accuracy. It offers auto-makeup gain, ensuring that no matter what you do to the Threshold and Ratio controls, you'll have a consistent output level.
Confused by compression? Read Compressors Demystified
Use EQ IQ for acoustic guitar magic
It's best to start with your track's low frequencies, rolling off your guitar's lowest output where it competes in the mix with kick drums and basses. Using a shelving EQ set at somewhere around 80 - 100Hz will generally clean up the bottom end of your mix. When you have lows balanced where you like them, seek out and destroy any resonances found around the 100 - 250Hz band. To give the guitar more space and presence in the mix, try peaking frequencies in the 3 - 7kHz range. Exactly how much should be a function of careful listening to the guitar within the mix.
Got a problem frequency? The Sonnox Oxford EQ is a 5-band EQ with selectable shelf settings on Low Frequency and High Frequency sections.
In an ideal world, with a sweet guitar in a great sounding room, effects are rarely needed. But if your recording seems flat or synthetic-sounding, a little effect magic might help. Adding a bit of reverb back into a lusterless guitar track can be just what the doctor ordered. Ditto for a little chorus and/or delay. Panning the dry sound to one side and the effect to the other can help add dimension to your guitar. The trick with acoustic guitar tracks is to keep a tight hand on effects so they never sound like effects. Keep things subtle.
If you're looking for classic reverb, consider reaching for the Waves Abbey Road Reverb Plates. This incredible plug-in offers precise modeling of four legendary Abbey Road reverb plates.
Need help choosing a mic or other recording gear? Give one of our knowledgeable and friendly Gear Heads a call at 800-449-9128 to help narrow down your options.