frequency response

A flat response tends to sound natural ; a mic with high frequency responce sounds brighter or more trebley. A mic that rolls off below the range of the instrument minimizes pick-up of room rumble; a mic that rolls off low frequencies within the range of the instrument tends to sound thin.
Most condenser mics have an extended high frequency response, making them suitable for cymbals or detailed sound, such as acoustic guitar, strings, piano and voice. Dynamic moving coil mics have a response adequate for drums, guitar amps, horns and woodwinds.

polar pattern

The more room ambience that is recorded, the more distant the instrument sounds. The more an instrument's leakage is recorded by other mics, the more distant it sounds. The polar pattern of a microphone affects the amount of leakage and ambience that are picked up.
An omnidirectional sounds more distant than a directional mic when both are placed the same distance from the instrument. Thus an omnidirectional mic must be placed closer to an instrument than a directional to reproduce the same sense of distance.

quantity of microphones

Use 2 mics (or a stereo mic) for an overall acoustic blend of instruments and room ambience. This is effective for orchestra, symphonic band, choir, string quartet, pipe organ, small folk group or vocal quartet.
Pop music is usually recorded with multiple mics. Miking every instrument lets the mixer control the volume balance.
For greatest clarity in multi microphone recording, use as few mics as necessary to get a good sound. Don't use 2 mics when one will do. A brass section of 4 players can be covered with either just one or with one mic for every 2 players. For a proper blend the instruments must be balanced acoustically in the studio while making the recording. Quiet instruments should be moved closer and vice versa.

microphone placement

Mike close (a few inches) to achieve a tight present sound. Mike further away (12" - 18") for a distant, spacious sound. Mike close to reject unwanted sounds and further away to add a live, loose, airy feel to overdubs of drums guitar solos and horns. Classical music is always recorded at a distance for hall reverberation as part of the sound. Distant miking to the extreme is called an ambient microphone. In a studio it is placed about 10ft or more from an instrument. Its output is mixed with the usual close placed mics.Two are often used for stereo. In concert ambience mics are placed over the audience.
When miking many instruments at once, leakage can be reduced by miking each instrument very close, so the mixer gain of each instrument can be turned down which reduces the leakage.
Because most instruments are designed to sound best at 18"or more away, a flat response mic placed at that distance tends to pick up a natural or well balanced timbre. When leakage forces you to mike close the tone quality may not reflect the sound of the entire instrument, e.g. the sound hole of a guitar resonates at around 80 - 100 Hz. A mic placed close to the hole hears and emphasizes this low frequency resonance, producing a boomy, bassy timbre that does not exist at a greater miking distance. To make this sound more natural roll off the excess at the mixer or use a mic with a bass roll off.
A natural tonal balance usually can be found at a miking distance equal to the size of the sound radiating part of the instrument. Place the mic as far from the instrument as the instrument is big.e.g. if the body of an acoustic guitar is 18" place the mic that distance. If this sounds too distant or muddy, move in a little closer.
To determine a good mic position for tone, listen to the instrument by closing one ear with your finger and move around until it sounds good. A trumpet radiates strong highs directly out of the bell but does not project them to the sides. Thus a recorded trumpet sounds bright when miked on axis to the bell and sounds more natural or mellow when miked off to one side. A piano sounds farely natural miked 1ft over the middle strings, sounds bassy and dull when under the sound board and sounds constricted miked in a sound hole.

on surface technique

When forced to mike near a hard reflecting surface, such as near stage floor or reflective baffles or a mic placed close to a piano lid a comb filter effect can be produced. The sound travelling to the mic from 2 sources (reflected and direct). Boundary mics have been designed for on surface mounting to avoid the unnatural tone.
An omni-directional boundary mic is taped to the underside of the piano lid, to a hard surface panel, or to a wall. A uni-directional boundary mic is used on the stage floor near the footlights, on a lectern or desk.

the 3 to 1 rule

When multiple mics are mixed to one channel, the distance between microphones should be at least three times the mic to source distance. Eg.2 mics are placed 1ft from their sound source, the mics should be at least 3ft apart. Following this rule prevents phase cancellations. Resulting in blurred coloured sound.

stereo miking(accurate localisation)

The stereo spread, or stage width extends from speaker to speaker. If the mics are placed improperly, the effect is either a narrow stage width or exaggerated seperation. A large ensemble should spread from speaker to speaker ; a quartet can have a narrower spread.


Left     LeftCentre     Centre     RightCentre     Right

Images localised accurately between speakers (listeners perception)

To judge these localisation effects, its important to position properly with respect to the monitors. Sit as far from the speakers as they are apart. The speakers appear to be 60 degrees apart, which is about the same angle an orchestra fills when viewed from the ideal position.

Simulated stereo effect.
If only one track can be spared
- Pan the track to the left channel
- simultaneously send it through a 20 millisecond delay
- pan the delayed signal to the right
- adjust the relative levels of the direct and delayed signals to achieve a spread from speaker to speaker.

types of stereo mic techniques

1.Coincident-Pair

Two directional mics are mounted with there grills touching and their diaphragms placed one above the other. They are also angled apart to aim approximately toward the left and right sides of the sound source or ensemble. The greater the angle between mics the wider the stereo spread.
A Coincident pair method with excellent localization is the Blumlein Array which uses two bidirectional mics angled 90 degrees apart and facing the left and right sides of the ensemble.
To make coincident recordings sound more spacious, boost the bass 4db (+2db at 600Hz) in the l - r or side signal.
A recording made with coincident techniques is mono compatible, the frequency response is the same in mono or stereo. There is no time or phase difference when both channels are combined to mono.

2.Spaced Pair

Two identical mics are placed several feet apart and aiming straight ahead. The omnidirectional pattern is the most popular for this method. The greater the spacing the greater the stereo spread. During playback,a phantom image of the center instruments is heard midway between the speakers.
If the spacing is 12ft, for instance, instruments slightly off centre are reproduced at the left or right speaker.This could be called an exaggerated seperation or ping pong effect. If the mics are less than 3ft apart the delays produced are inadequate to provide much stereo spread. When a third mic is placed midway it is a good balance and the stereo is not exaggerated.
A disadvantage when combining both mics to mono they can sometimes cause phase cancellations of various frequencies. Spaced mics can tho produce a good ambience to the listener. Another advantage is that omni condenser mics are used which have a more extended low range than a uni directional and tend to have less off axis colouration.

3. Near Coincident Pair.

The most common example uses two cardioid mics angled 110 degrees apart and spaced 7 inches apart horizontally. This method tends to provide accurate localisation.

summary :
Coincident pair.

1. Images are sharp
2. Stereo spread ranges from narrow to accurate
3. Signals are mono compatible.

1. Off center images are diffuse.
2. Stereo can be exaggerated if 3rd mic not used
3. Warm sense of ambience
4. Signals tend not to be mono compatible.

1. Images are sharp
2. Stereo spread is accurate
3. A greater sense of air is created

mic requirement

Most acoustic instruments produce frequencies from about 40 Hz(string bass and bass drum) to about 20,000 Hz (cymbals, castenets, triangles) A microphone with uniform response between these frequencies does full justice to the music.The highest octave from 10 kHz to 20 kHz adds transparency, air and realism to the recording.
Roll off frequencies below 80 Hz to eliminate rumble unless recording organ or bass drum fundementals. Sound from an orchestra or band approaches the mics from a broad range of angles. To reproduce all the instruments timbres equally well ,the mic should have a broad, flat responce at all angles within at least + or - 90 degrees (the polar pattern should be uniform). For sharp imaging the microphone pair should be well matched in frequency response,phase response and polar pattern.

instruments

Drums.

Creating a good drum sound lies in careful tuning. Old, used drum heads tend to produce a dull muffled sound ; new heads sound crisp.

1.Tom Toms
Give the most pleasing tone when the heads are tuned at the same pitch the shell resonates. Take off the heads and remove damping mechanism (a possible source of rattles). Put the top head on and tighten the lugs by hand. Then using the drum key, tighten opposite pairs of lugs one full turn. After all the lugs are tightened,repeat the process, tightening one half turn. Then apply heavy pressure to the head to stretch it. Continue tightening one half turn until the desired pitch is reached. Keep the bottom head off the drum for best projection and the broadest range of tuning. If the bottom head is required for extra control of sound, projection is best if the bottom head is tighter than the top - tuned a 4th above the top head. There is a muted attack, alot of ringing and some note bending. If the bottom head is looser than the top, the tom rings less and has good attack.

2.Kick Drum.
For the kick drum, a loose head gives alot of slap and attack, and almost no tone. The opposite for a tight head. A hard beater provides more attack.

3.Snare Drum.
Tune with the snares off. A loose batter head gives a deep fat sound, a tighter head sounds bright and crisp. Set the snare tension just to the point where the snare wires begin to choke and then back off a little. The buzz from sympathetic vibrations can be controlled by a cotton wad between the snare and drum stand.

Damping and noise prevention
If tomtoms or snare ring excessively, tape some gauze pads or folded handkerchiefs to the edge of the heads. Put tape on 3 sides of the pad so that the untaped edge is free to vibrate and dampen the head motion. To reduce excessive cymbal ringing, apply drafting tape in radial strips from bell to rim. Oil kick drum pedal. Tape rattling hardware.

miking the drum set

For a tight sound place mics very close to the edge of each drum head. For a more open airy sound move the mics back a few inches, use fewer mics or mix in some boundary or omni condensers placed several feet away. Sometimes a jazz drum set can be miked with 2 overhead mics and one kick drum mic.

Snare

Bring the mic in from the front of the set on a boom. Place it about 1"above the rim (or 1" in from the rim) angled down to aim where the the drummer hits.
You may want to aim the the snare mic partly toward the the hi-hat to pick up both instruments. Place the mic so it is not hit by the hi-hat air puff.
Either a cardioid condenser or cardioid dynamic works fine - a cardioids proximity effect can add fullness to the snare beat.
If miking snare and hi-hat seperately,bring the boom in under the h/h and aim the snare mic away from the h/h for better isolation. Or attach a miniature condenser mic a few inches over the snare drum rim.
Mics with opposite polarity can be used for miking top and bottom of snare drum heads. A mic under gives a zippy sound;a mic over gives a fuller sound.

Hi - Hat

Usually the snare mic or ambience mikes pick up enough but a condenser mic about 6" above the edge of the hi-hat aiming at the side furthest from the drummer. Mike from aiming above.

Tom - Toms

Can be miked seperately or with one mic between the pair. A typical way uses a cardioid dynamic or condenser placed about 1" above the rim (or about 2" in from the rim) angled down about 45 degrees toward the drum head. Again the cardioids proximity effect gives a full sound.
Alternatively, tape a mini condenser to the toms, peeking over the top rim of each drum. Or try a bi-directional mic between the toms.
If there is leakage from the cymbal take the cardioid tom mics and aim their ' dead ' rear at the cymbals.
Or remove the bottom heads from the toms and mike inside a few inches from the head, off centre. The sound picked up inside the toms has less attack and more tone than the sound picked up outside.

Kick Drum

To damp the vibration and tighten the sound place a blanket inside the drum pressing against the beater.
A mic commonly used is a cardioid dynamic with an extended low frequency response. Place it inside on a boom,a few inches where the beater hits and slightly off centre. Placement close to the beater picks up a hard sound, off centre picks up more skin tone, and further away a boomier shell sound. For a bigger sound build a small tunnel with blankets and a chair and put the mic outside the kick drum.
A miniature omni-condenser can be hung inside near the beater for a clearly defined attack.
Cutting EQ around 300 to 600Hz helps to remove the ' cardboard box ' sound, and boosting several db around 2.5 to 5kHz adds attack, ' click ' or ' snap '.
The recorded sound should be a powerful low end thump plus the click or snap of the beater hitting the drum head.

Cymbals

Place cardioid condenser mics 1 to 3ft overhead and above the cymbal edges. Two mics overhead can be straight down or angled apart for better isolation. For mono compatibility mount the mic grills together and angle the mics apart.
Place mics to pick up all cymbals equally. Usually not much gain is needed on the overhaeds because the cymbals leak into the drum mics. Sound should be crisp and smooth, not sizzly and harsh.
Place ambient mic(s) about 10 to 20ft to give an open, airy sound when mixed with the other mics. Sometimes ambience mics are compressed heavily for special effect. Boundary mics can be taped to hard surfaces around the drummer or put them on the floor under the toms and near the kick drum.

recording with 3 mics

1. Tape or clip one mini mic near the left rack tom and the snare drum. Picking up, hi-hat, snare, left tom and cymbals.
   
2. Tape or clip another mini mic near the right tom and the floor toms.
   
3. Place the third inside the kick drum.
   

Move the mics closer or further and raise or lower the cymbals until all the elements are balanced. With a little bass boost it will make a good sound with even coverage.

recording with 2 mics

1. Clip a mini omni condenser mic to the snare drum rim about 4" above the rim, in the center of the set, aiming at the hi-hat
2. Put another mic in the kick drum.

drum eq

1. Various EQ can enhance the recorded sound.
2. Boost around 200 Hz for fullness on snare drum and high toms, and around 100 Hz on floor toms. Or use a cardioid mic up close for its bass boosting proximity effect.
3. Roll off some bass on the snare for extra clarity.
4. Boost at 5 kHz on snare and toms for attack and crispness.
5. Boost at 10 kHz or higher on cymbals and filter out frequencies below
500 Hz to minimise low frequency pick up.
6. Boost around 2.5 to 6 kHz on bass drum for punch, and filter frequencies above 5kHz on bass drum to reduce leakage from cymbals.

percussion instruments

Mike at least 1ft away and use a dynamic mic with an extende high frequency response.
Congas, bongos and timbales can be covered with a single mic between the pair. A single-D moving mic with a presence peak gives a full sound and clear attack.
For xylos and vibes, place 2 cardioid mics 18" above aiming down. The mics should be crossed (angled 135 degrees apart) or placed about 2ft apart. Allowing for stereo and good coverage.

acoustic bass

Use a mic with an extended low frequency response. For a well defined sound place mic a few inches out front,above the bridge. Aim into the f hole for a fuller sound. Watch out for proximity effect with a closely placed cardioid mic.

The following techniques increase isolation.

1. Wrap a mini omni condenser in foam rubber and mount it in an f hole
2. Tape the cable of a mini mic to the bridge.
3. Wrap a regular mic in foam padding (except the grill) and squeeze behind the bridge or between the tailpiece and the body.
4. Try a direct feed from a pick up.
5. Wrap a condenser lavaier mic in foam and stuff in f hole. Mix this mic with the pick up to round out the tone. If needed roll off the bass of the f hole mic. Try flipping the polarity of the mic.

electric bass

A combination of direct and miked sound provides clarity and a deep low end. The mic can be a condenser or dynamic with a good low fr.response placed about 1" to 1 ft away from the speaker. When combining with a mic signal make sure they are in phase with each other. To do this,set the to equal levels and reverse the polarity of either.
The bass should be constant in level (a dynamic range of about 6db) to be audible throughout and to avoid saturating the tape.Run through a compresser at a Ratio of 2:1 to 4:1, set the attack time fairly slow at 8 to 20 milliseconds, and set the release fairly fast at 1/4 to1/2 second.
EQ can increase the clarity.It often helps to cut at 125 to 400 Hz and/or boost at 1500 to 2000 Hz.On small speakers a boost at 300 to 500 Hz helps the bass ' speak '.
If the bass part is full and sustained, its probably best to deemphasize the pluck and let the kick drum define the rhythmic pattern. If both are rhythmic and work independently, plucks should be audible.

saxophone

For a natural tone balance place mic about 18" away aiming at the players left hand, about one third to one half of the way down the wind column. A brighter sound might be found by a close mic positioned just above the bell, aiming at the holes.

flute

One effective mic placement is a few inches from the area between the mouthpiece and the first set of finger holes. A pop filter may be needed. A mini mic attached to the flute a few inches above the body, between the mouthpiece and the finger holes.

brass

Try miking the bell at an angle and distant with a flat response mic to give a more natural tone. The waveform of a trumpet on axis has a strong spike sound that can overload a condenser. So mic placement off axis is more controllable. Close mic placement (about 1ft) gives a tight sound ; distant placement (about 5ft) yields a fuller more dramatic sound. Several players can be grouped around a single omni mic or a cardioid mic placed below aiming up. Or play to a boundary mic taped on window or a large panel.

acoustic guitar

To achieve a more natural sound when miking close to the sound hole, roll off low fr. on the mixer (-10db or more at 100 Hz ).
A mini omni condenser attached halfway between the sound hole and the bridge, near the low E string provides good fidelity. For more isolation, tape a mini directional in the sound hole and roll off the bass on the mixer.
If leakage is not a problem a more natural sound can be achieved by miking from 12 to 18" from the sound hole. A closer placement of 6" over the top, over the bridge and even the front soundboard.
A woody mellow tone from 4" in front of the bridge. Here the vibrations of the soundboard are emphasized, starting around 200 Hz. This position reduces pickup of string and pick noise.
For classical guitars - place mic 3 to 8ft away, closer to reduce room reverb and further to increase.For a more realistic ' air ' record in stereo. Angle the two mics 90 degrees apart with the grills about 8" apart.

electric guitar and amp

Flip any polarity switch on amp to the lowest hum position. Use a cardioid dynamic with a presence peak in the fr.response (a boost around 5 kHz). Mike the amp about 1" to 1ft with the mic aiming at the center of one of the speaker cones. Placement in front sounds bright and trebley ; off center more mellow and reduces amp hiss. If overdubbing a dynamic mic placed 5ft away mixed with boundary mics for ambience.
If mixer is a high impedance unbalanced mic input (1/4" phonejack) Plug directly into the mixer. If mixer has 3 pin balanced inputs use a DI box. Both will sound cleaner though.

vocals

A vocalist should back off 8" to 2ft from mic to give a natural tone. Use a flat response condenser mic.
Vocals are typically boosted between 2 kHz and 5 kHz to help them stand out from the instruments.
Vocal groups can be recorded in stereo from about 2 to 4 ft away. If their balance is poor, try miking individually or sack them.


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