The microphone is the first link in the chain, and nothing after it can fully undo its choices. Different microphones hear the same voice very differently. Choosing the right one - for the singer, the song and the room - is one of the most important decisions in vocal production.
How microphones work
A microphone turns sound pressure into an electrical signal. How it does that defines its character.
Dynamic microphones
A diaphragm attached to a coil moves in a magnetic field. Dynamic mics are robust, handle very loud sources, need no external power and pick up less of the room. The Shure SM58 is the standard live vocal mic; the SM7B is a broadcast and studio favourite, used on many famous records.
- Strengths: forgiving in untreated rooms, great with loud and aggressive singers, rugged.
- Weaknesses: less detail and air than condensers; many need a lot of preamp gain.
Condenser microphones
A thin diaphragm forms one plate of a capacitor; sound changes the gap between the plates. They need power - usually 48V phantom power from your interface. Condensers are more sensitive, more detailed and capture more high-frequency air.
- Large-diaphragm condensers are the classic studio vocal microphone - flattering, detailed, present. The Neumann U87 is the reference many studios are built around.
- Small-diaphragm condensers are more accurate and less flattering - better suited to acoustic instruments than to lead vocals.
- Strengths: detail, sensitivity, presence.
- Weaknesses: they hear the room as clearly as the singer. In an untreated room, a condenser can make a vocal sound boxy and reflective.
Valve (tube) condensers
Condensers with a vacuum tube in their electronics, adding warmth, saturation and a smooth top end. Many classic vocal recordings were made on valve microphones.
Ribbon microphones
A very thin metal ribbon suspended in a magnetic field. Smooth, dark and natural, with a gentle top end that can tame harsh voices. Fragile - some older ribbons can be damaged by phantom power or strong blasts of air.
Polar patterns
A polar pattern describes which directions a microphone picks up sound from.
- Cardioid - picks up mainly from the front, rejecting the rear. The standard for vocals.
- Supercardioid and hypercardioid - tighter at the front, with a small pickup lobe at the rear. Common on live mics.
- Figure-of-eight - front and back equally, rejecting the sides. Natural for ribbons; useful for duets or capturing more room.
- Omnidirectional - all directions equally. Natural and open, but picks up the whole room.
Many large-diaphragm condensers have a switch to choose between patterns.
Proximity effect
Directional microphones boost low frequencies as the source gets closer. Sing right on the mic and the voice gets bigger, warmer and boomier; step back and it gets thinner. Broadcasters use proximity effect for a deep, intimate sound. In singing, it explains why a vocal's tone changes when a singer moves - and why consistent distance matters.
Choosing a microphone
There is no best vocal microphone - only the best one for this singer, in this room, for this song.
- Match the voice. A bright, sibilant voice may suit a darker microphone; a dull voice may come alive on a brighter condenser.
- Match the room. In an untreated room, a dynamic microphone often beats an expensive condenser.
- Match the song. An aggressive rock or rap vocal may want a dynamic; a delicate ballad a detailed condenser.
- Shoot it out. If you have more than one microphone, record the singer on each - same song, same level - and choose by ear.
Do this now
- List every microphone you have access to and identify its type and polar pattern.
- Record the same vocal phrase at 5 cm, 15 cm and 30 cm from a cardioid microphone and listen for proximity effect.
- If you can, record the same phrase on a dynamic and a condenser microphone in your room. Which sounds better - and why?