Acoustic instruments are honest. A vocal can hide a little behind effects, but a guitar or piano recorded at home carries the room, the fridge and the creaky chair straight into the mix. The good news is that recording acoustic instruments at home depends more on where you put things than on what you buy. Moving a microphone ten centimetres often does more than a new one.
Choose the room before the microphone
Small, bare rooms with parallel walls sound boxy and ring. Clap once in the middle of the room and listen: a fast metallic flutter means hard reflections. A furnished room with a sofa, curtains, a rug and full bookshelves usually sounds calmer.
A few rules that help in most homes:
- Don't put the player in a corner or right against a wall. Bring them out into the room.
- Hang a thick blanket or duvet behind the player and, if you can, behind the microphone. It soaks up the reflections that reach the mic first.
- Don't deaden the room completely. Acoustic instruments sound natural with a little air around them. You want calm, not dead.
Try two or three spots in your home. Record ten seconds in each, listen back on headphones and keep the one that sounds least boxy.
Noise you've stopped hearing
Your ears ignore the fridge. The microphone doesn't. Before recording, stand in the room and listen for:
- the fridge, air conditioner, heater or a computer fan;
- traffic, neighbours, a lift or a dog;
- the instrument's own noises: string squeaks, piano pedals, a creaking stool;
- you: bracelets, a rustling jacket, breathing close to the mic.
Switch off what you can, and if you unplug the fridge, set a reminder to plug it back in. Choose a quiet chair and record at the quietest time of day. Put your phone in airplane mode, both for notifications and because some phones cause a buzz in nearby cables.
Start each session by recording ten seconds of silence. Turn it up and listen. If you hear hum or hiss, track it down now rather than in the mix.
Mic placement for common instruments
The rule for everything: place the mic, record a short take, listen, move it a little, repeat. Trust your headphones and your ears, not a diagram.
Acoustic guitar
Don't point the mic straight at the sound hole, which sounds boomy. A classic starting point is where the neck meets the body, roughly 15 to 30 centimetres away. Move toward the sound hole for more body, toward the neck for more brightness and string detail. Another good position is over the player's shoulder, pointing down at the guitar, close to what the player hears.
Piano
For an upright, open the lid and place the mic above the open top, or take off the front panel and aim at the hammer area from some distance. If you have a digital piano or keyboard, don't mic its speakers. Record it directly through its line outputs into your audio interface. It will sound cleaner every time.
Bowed and plucked instruments
A violin sends its sound up and forward from the body, so a mic placed above and slightly in front, at arm's length or more, sounds more natural than one close to the strings. Lutes and other plucked instruments behave much like the guitar: avoid aiming straight at the sound holes and look for the sweet spot between the neck joint and the body.
Hand percussion
Frame drums and darbuka are loud and sharp. Keep the mic further away than you'd expect and set the input gain lower so the hits don't clip.
One take, more than one angle
If you have two microphones, record them at the same time: one close for detail, one further back for the room or the whole instrument. In the mix you can blend them to taste.
Two mics on one source can partly cancel each other and make the sound thin. Listen to both together. If the combination sounds weaker than either mic alone, flip the polarity on one channel and keep whichever version sounds fuller. A well-known spacing guideline is the three-to-one rule: the second mic should be at least three times as far from the first mic as the first mic is from the source.
With one microphone, record a few full takes in different positions and choose the best. Don't stack takes from different positions as if they were a stereo pair. Doubling is different: two separate performances of the same part, panned left and right, are a common way to make a guitar sound wide.
If your guitar has a pickup, record the pickup and the mic together. The pickup alone often sounds plasticky, but blended quietly under the mic it adds focus.
Levels, tuning and takes
Leave plenty of headroom. At 24-bit there's no need to record hot, and peaks well below the top of the meter are safer than a clipped take you can't use.
Tune before every take, not just at the start, because acoustic instruments drift as the room warms up. Go for a few complete takes rather than dozens of short repairs, so tone and feel stay consistent. And name files as you go, for example "Guitar close, take 3". In a week you won't remember which one was the good one.