Microphones and polar patterns: dynamic, condenser, ribbon, XY and ORTF.

Choosing a microphone is not a matter of browsing a catalogue, but of three linked decisions: the capsule’s technology, the direction in which it is sensitive, and the distance and angle at which you position the source. Confusing the three produces takes that sound distant, dull or uncontrolled in the bass, and the problem is almost always the combination rather than the microphone itself.

This chapter covers just that: Dynamic / condenser / ribbon microphones, the range of Cardioid / omni / figure-of-8 / supercardioid patterns, capsule behaviour as you move closer, what happens when the source moves off-axis, and the two stereo recording techniques most often used in studios: XY and ORTF.

Three capsule technologies: dynamic, condenser and ribbon

The three families convert sound into electricity in different ways, which is where their character comes from.

A dynamic microphone uses a coil attached to the diaphragm that moves within a magnet’s field. It is robust, handles very high levels without complaint and, being relatively insensitive, picks up less of its surroundings: in an untreated room, it is usually the safest option.

A condenser uses two plates forming a capacitor whose capacitance changes as the diaphragm moves. It is more sensitive and detailed, captures subtle attacks and allows comfortable working distances, but also brings computer noise, traffic and reflections from the wall behind you into the take. Within this family, the large-diaphragm version shines on voices and piano; the small-diaphragm version is more directional and compact, common on percussion and as a pair for stereo recording.

A ribbon microphone suspends a very light metal strip in the magnetic field. Its warm character and natural high-frequency roll-off suit brass, kick drum shells and voices with marked sibilance. The trade-off is delicacy: older ribbons tolerate air blasts and excessive levels poorly, and many require power or a preamp with plenty of gain.

In practice, the room decides the choice before the source does. Without acoustic treatment, the dynamic wins; with some absorption and controlled noise, the condenser earns its place. The guide to dynamic microphones, condensers and polar patterns expands this comparison and connects it to phantom power.

Cardioid / omni / figure-of-8 / supercardioid

Polar pattern determines where the capsule picks up sound. The complete selection is Cardioid / omni / figure-of-8 / supercardioid, and each solves a different problem.

Cardioid is the standard: it picks up from the front and rejects sound arriving from behind, reducing ambience and increasing distance from the source. Omni picks up equally in all directions, with the advantage of no proximity effect and more natural bass, but the disadvantage of bringing the entire room into the take. Figure-of-8 picks up from front and rear with a side null, useful for face-to-face interviews and stereo techniques such as Mid/Side. Supercardioid narrows the front angle and improves side rejection, at the cost of a rear lobe that requires care over monitor and noise placement.

There are two practical consequences. First: with narrower patterns, you have to aim more accurately, because the sound fades sooner when it leaves the axis. Second: the null is not exactly at 180 degrees in highly directional patterns, so placing noise directly behind the microphone requires checking by listening rather than assuming.

Proximity effect and off-axis coloration

Proximity effect is the bass reinforcement that appears when the source approaches a directional capsule. DPA explains it through wave physics: front and side sound do not arrive by the same path, and at close range that difference becomes more energy in the bass. It can add body to an announcer’s voice, but becomes a problem when distance changes mid-take: the tone shifts and the phrase sounds inconsistent. The solution is not EQ, but setting a working distance and keeping it.

Off-axis coloration is the other behaviour to understand: when the source moves off-axis, the microphone does not just lose level, it changes colour. High frequencies fall away first and the sound becomes darker, sometimes slightly nasal. That is why a voice turning to one side cannot be completely fixed by raising the volume: a different sound is arriving. The guide to vocal recording: microphone, preamp, gain and bleed covers technique in front of the capsule as applied to voice.

XY and ORTF techniques: two capsules, two ways to build an image

When you want to record in stereo with two microphones, the two classic references are XY and ORTF.

In XY, the two capsules are coincident, pointing in opposite directions at an angle usually of 90 degrees. Because they are at the same point, the signal reaches both channels at the same time, so the image holds up very well in mono and there are hardly any phase problems. The soundstage it produces is restrained.

ORTF, named after the French broadcasting organisation, positions two cardioids with capsules 17 cm apart and an angle of 110 degrees. It combines level and time differences, giving a wider image than XY and more convincing room sound while maintaining a reasonable mono sum. It is a very common option for choirs, ensembles and an open piano.

The choice depends on your priority. If the destination may be mono—radio, social media or single-channel systems—XY is the safe option. If you want width and a sense of the room with reasonable control, choose ORTF. And if you need an even bigger soundstage, a spaced pair provides it, but requires care with phase; that family of techniques is developed in the guide to AB, Blumlein, Mid/Side and close recording.

Beyond the abbreviations, the height and orientation of the whole setup determine the take. At a height above the source, with capsules aimed at the point where the sound is fullest, you get a stable image; too low, and sound from the floor enters the channels; too high, and the centre of the image is lost. The same final check applies to both techniques: listen to the mono sum before accepting the take, because cancellation is only audible when the two channels meet.

Choosing according to room and source

The decision order that works is the reverse of browsing the catalogue:

1. Room first. Is it treated, is there background noise, is it a small room? If the room does not help, start with a cardioid dynamic and move closer to the source.
2. Source second. Powerful voices, kick drum shells and amplifiers need capsules that handle level. Choirs, strings and piano open the door to condensers and stereo recording.
3. Distance and angle. Fix distance to control proximity effect and angle to control how much room enters; both change the tone as much as EQ.
4. Stereo only when it adds something. If the track will be heavily processed or mono, one well-positioned microphone usually performs better than two poorly managed ones.

The most common mistakes

• Buying for sensitivity rather than the room. An expensive condenser in an untreated room records that room in great quality.
• Moving during the take. Proximity effect changes the tone in real time, and afterwards no EQ can restore consistency.
• Ignoring off-axis coloration. Correcting the source’s position pays off more than equalising sound that already arrived dull.
• Copying measurements without listening. XY and ORTF are starting points: angle, distance and height are adjusted to source and room.
• Neglecting the null. With supercardioid, the rear lobe picks up what you thought was blocked.

Next step

With capsule and pattern chosen, decide how many microphones to use and how to distribute them in the space: AB, Blumlein and Mid/Side stereo techniques, and recording with close, room and spot microphones.