Studio Mic Placement, Instrument by Instrument

Placement is the only processing that happens before the signal exists. Everything downstream — preamp gain, EQ, whatever you reach for in the mix — operates on a recording a microphone position has already decided. Move a mic fifteen centimetres and you have changed the balance between an instrument's attack and its body, between the instrument and the room, and between that mic and every other one in the building.

The usual mistake is treating placement as a ritual before the real work — textbook spot, then fix the tone with an equaliser. That runs backwards. A mic moved a few centimetres is a filter shaped by the instrument's own radiation, and no EQ curve draws that shape. The second mistake is judging a position in isolation, because on a kit or a bass rig one mic's position changes what the other one is worth. The first recording lesson gets a microphone in front of a source. This one is about the centimetres.

The Sound Hole Is a Vent, Not a Target

Start an acoustic guitar with a small-diaphragm condenser aimed at the twelfth fret, 15 to 30 cm (6 to 12 in) out — near where the neck joins the body on most instruments. It works by splitting the difference between two sources that sound nothing alike: strings and fretboard supply the pick attack and the fret noise, the body supplies weight and sustain. At a foot out both arrive in usable proportion.

The sound hole is not where the guitar comes out. It is where the box vents — a narrow band of low frequency pushed far harder than anything else the instrument does. Aim into it and the low end swells out of proportion, and thinning that afterwards takes the body along with the boom.

Then move for a named problem, one axis at a time. Thin and papery: drift toward the sound hole. Boomy: drift toward the bridge, trading body for string definition. Inside about 15 cm two things happen together — the proximity rise the microphones lesson explains, and a mic close enough to hear only part of a large instrument, so a shift of the player's shoulders becomes a level change.

Across the Cone Is the Tone Control That Actually Works

A guitar cabinet is not one source. A twelve-inch driver radiates its top end from the middle of the cone and beams it forward, while the low end comes off the whole cone and spreads. So where the mic sits across the face of that speaker sets the tonal balance before any other decision — including the one about distance.

Start with a dynamic 2.5 to 5 cm (1 to 2 in) off the grille cloth, on axis, pointed at the edge of the dust cap — the small dome at the centre of the cone. That is the compromise position by construction: dead centre on the cap is the brightest and hardest place on the speaker, the outer edge of the cone the darkest and thickest, and the boundary between them is where most records live.

The corrective move is lateral, and it is small. Fizz on a distorted rhythm part: slide an inch toward the cone edge and listen again. A part that vanishes under the vocal: slide back toward the cap. Pulling the mic away from the grille is a different move entirely — it trades directness for room, and on a directional mic it gives back the low end that proximity was adding.

Choose the Vocal Distance Before You Choose Anything Else

Set a large-diaphragm condenser 20 to 30 cm (8 to 12 in) from the singer's mouth, with a pop screen at least 10 cm (4 in) in front of the capsule and turned slightly off parallel so its own reflections do not comb with the mic. That distance is not a compromise — it is the range where a directional capsule's low-end lift is present but gentle, so one step forward in a chorus does not rewrite the bottom of the track.

The screen does two jobs and the second one matters more. It stops the blast of air from a plosive — wind rather than sound — and it fixes the working distance. A singer who drifts is the most common reason a vocal will not sit still in a mix.

Move for the complaint you actually have. Thin and small: closer, and let proximity do the work. Boomy: back off. In a quiet enough room an omnidirectional capsule is the other answer — it has no proximity effect whatsoever, so you can work close with no low-end penalty. Plosives surviving the screen usually mean the singer is firing straight down the axis; turn the mic a few degrees and let the breath cross the capsule rather than hit it.

Every Close Mic on a Kit Is a Room Mic for the Rest of It

Put the kick mic through the port in the front head, 5 to 10 cm (2 to 4 in) inside, pointed at the spot where the beater lands. Inside the shell you are close to the impact and short of the resonance that develops in front of the drum, so it buys attack. Draw it back to the port or just outside and the weight returns — along with the air the port throws on every hit, which records as wind rather than a note. Start the snare about 5 cm (2 in) above the head, capsule 3 to 5 cm (1 to 2 in) inside the rim, aimed between the centre and the edge. Drop it closer to the head for body; slide it toward the rim for ring and crack.

The spacing rule from the physics lesson — second mic at least three times as far from the first as the first is from its source — is trivially satisfied in one place on a kit and unsatisfiable in another. A snare mic 5 cm above the head asks for only 15 cm of clearance, and the kick mic clears that by about a metre. A hi-hat mic parked beside it does not, and that is where a snare track picks up the hollow edge no EQ removes. Overheads cannot meet the rule at all: a pair a metre above the snare would need three metres between them, wider than the kit and wider than any image you want.

So overheads are not governed by how far apart they sit — they are governed by sitting the same distance from the snare, so the loudest thing in the room reaches both capsules at once and the sum stays solid. Measure it with a cable from the centre of the snare head to each capsule; your eye is not good enough. Beyond that shared constraint the configurations are genuinely different geometries, and practice varies more here than anywhere else on this page:

• Spaced pair — two mics well apart above the kit, with no agreed spacing at all; published advice starts around 40 cm (16 in) and goes wider, so the snare match is the only firm rule.
• XY — two cardioids stacked vertically so the capsules almost touch, with 90 degrees between their axes, though 135 degrees is also in common use.
• ORTF — capsules 17 cm (6.7 in) apart with 110 degrees between the axes, roughly the spacing of a pair of ears, and wide enough that the snare check genuinely matters.
• Glyn Johns — one mic about a metre (40 in) straight above the snare and a second beside the floor tom aimed across at the hi-hat, both the same distance from the snare centre.

Piano and Bass Both Hand You Two Captures and One Track

A grand with the lid on the long stick takes two mics about 30 cm (12 in) above the strings and 30 cm apart, just in front of the hammers, one over the bass strings and one over the treble. Slide the pair toward the hammers for attack and definition, or toward the tail for warmth, losing percussiveness as you go. The spacing is the part that bites — too close together and the two channels comb against each other, too far apart and the middle of the instrument falls into a hole between them.

Bass hands you the same problem in different clothes: record a DI and a miked cabinet at once, and choose afterwards. The cables lesson covers what the box is doing; here it is simply a second capture of one performance, arriving at a different time. A large-diaphragm dynamic a few inches off the cone and slightly off centre takes the amp — the DI takes the instrument with no room and no bleed, and it survives the discovery at mixdown that the amp tone was wrong.

Those two captures are not simultaneous. At 343 m/s a mic 30 cm (1 ft) off the grille hears the cabinet 0.88 ms after the DI has already reached the recorder. Sum a signal with a copy delayed by 0.88 ms and the first cancellation dip lands near 570 Hz — straight through the region that makes a bass audible on a phone speaker. Slide the DI later by that much before judging the blend, and check polarity while you are in there. If flipping it makes the low end fuller, it was wrong.

What to Do Before You Reach for the EQ

• Move the mic first, one axis at a time — change two things at once and you have learned nothing about either.
• Match path lengths before you match levels — overheads, piano pairs and DI-plus-amp all get summed, and a mismatch reads as a hole, not as a delay.
• Measure with a cable, not by eye — snare centre to each overhead capsule is the one distance worth being pedantic about.
• Check the 3:1 rule at the hi-hat — a snare mic 5 cm above the head wants 15 cm of clearance, and the hat mic is usually what breaks it.
• Pick a vocal distance and mark the floor — at 20 to 30 cm a step forward is a bass boost, and nothing downstream separates that from the performance.
• Record the DI even when the amp sounds right — one extra channel buys back the whole decision three weeks later.
• Write down what worked and where — a published starting position is a starting position for someone else's room, player and instrument.