Chapter 6Chapter 6MicrophonesMicrophones

MicrophonesMicrophones

Transducer: device that changes one Transducer: device that changes one form of energy into anotherform of energy into another

Mics and speakers: sound to Mics and speakers: sound to electrical signalelectrical signal

Microphones: typesMicrophones: types

Dynamic: a coil of wire attached to a Dynamic: a coil of wire attached to a diaphragm suspended in a magnetic diaphragm suspended in a magnetic field. field.

Sound waves vibrate diaphragm, coil Sound waves vibrate diaphragm, coil vibrates in magnetic field and vibrates in magnetic field and generates a electrical signal similar generates a electrical signal similar to sound waveto sound wave

Microphones: DynamicMicrophones: Dynamic

Tends to have rougher responseTends to have rougher response Rugged and reliableRugged and reliable Handles heat, cold, and high Handles heat, cold, and high

humidityhumidity Preferred for high SPL: guitar amps, Preferred for high SPL: guitar amps,

drumsdrums If flat response, can take the “edge” If flat response, can take the “edge”

off sounds (woodwinds, brass)off sounds (woodwinds, brass)

Microphones: CondenserMicrophones: Condenser

Sometimes called capacitor micSometimes called capacitor mic 2 parts: conductive diaphragm and metal 2 parts: conductive diaphragm and metal

backplate, spaced very close togetherbackplate, spaced very close together Both charged with static electricityBoth charged with static electricity When sound waves strike diaphragm, it When sound waves strike diaphragm, it

vibrates, varying the spacing between the vibrates, varying the spacing between the platesplates

This variation generates a similar signal to This variation generates a similar signal to incoming sound waveincoming sound wave

Diaphragm mass is lower, responds faster to Diaphragm mass is lower, responds faster to rapidly changing sound waves (transients)rapidly changing sound waves (transients)

Microphones: CondensersMicrophones: Condensers

Condenser mics need external power Condenser mics need external power supply (battery or phantom power)supply (battery or phantom power)

Phantom power: 12 to 48 volts Phantom power: 12 to 48 volts supplied through XLR cablesupplied through XLR cable

Most mixers have a switch to turn on Most mixers have a switch to turn on phantom powerphantom power

Microphones: Condenser Microphones: Condenser traitstraits

Wide, smooth frequency responseWide, smooth frequency response Detailed sound, Extended HighsDetailed sound, Extended Highs Omni type has excellent low-Omni type has excellent low-

frequency responsefrequency response Transient attacks sharp and clearTransient attacks sharp and clear Preferred for acoustic instruments, Preferred for acoustic instruments,

cymbals, studio vocalscymbals, studio vocals Can be miniaturizedCan be miniaturized

Microphones: RibbonMicrophones: Ribbon

Thin metal foil or ribbon is suspended Thin metal foil or ribbon is suspended in a magnetic fieldin a magnetic field

Sound waves vibrate the ribbon in Sound waves vibrate the ribbon in the field and generate a electrical the field and generate a electrical signalsignal

Microphones: RibbonMicrophones: Ribbon

Prized for its warm, smooth tone Prized for its warm, smooth tone qualityquality

Delicate, damaged by temperature Delicate, damaged by temperature and humidity changesand humidity changes

Complements digital recordingComplements digital recording ExpensiveExpensive

Microphones: Polar PatternsMicrophones: Polar Patterns

Polar pattern refers to the way a Polar pattern refers to the way a microphone responds from different microphone responds from different directionsdirections

Graph based on sensitivity measured Graph based on sensitivity measured in decibels.in decibels.

Uni-directional, Omni-directional, Bi-Uni-directional, Omni-directional, Bi-directional (figure-8)directional (figure-8)

Three types of unidirectional patterns: Three types of unidirectional patterns: cardioid, supercardioid, and cardioid, supercardioid, and hypercardioidhypercardioid

Microphones: Omni-Microphones: Omni-directionaldirectional

All around pickupAll around pickup Picks up room reverbPicks up room reverb Not much isolationNot much isolation Low sensitivity to popsLow sensitivity to pops Low handling noiseLow handling noise No up-close bass boost (proximity effect)No up-close bass boost (proximity effect) Extended low frequency response Extended low frequency response

(condensor) great for organ, orchestra, (condensor) great for organ, orchestra, etc…etc…

Lower cost (in general)Lower cost (in general)

Microphone: Omni PatternMicrophone: Omni Pattern

Microphones: Unidirectional Microphones: Unidirectional (cardioid, supercardioid, (cardioid, supercardioid,

hypercardioid)hypercardioid) Selective pickupSelective pickup Rejection of room acoustics, Rejection of room acoustics,

background noise, and leakagebackground noise, and leakage Up-close bass boostUp-close bass boost Better gain-before-feedback in live Better gain-before-feedback in live

soundsound Coincident or near0coincident stereo Coincident or near0coincident stereo

mikingmiking

Microphone: CardioidMicrophone: Cardioid

Broad-angle pickup of sources in Broad-angle pickup of sources in front of micfront of mic

Maximum rejection of sound Maximum rejection of sound approaching the rear of the micapproaching the rear of the mic

Most popular patternMost popular pattern

Microphone: CardioidMicrophone: Cardioid

Microphones: SupercardioidMicrophones: Supercardioid

Maximum difference between front Maximum difference between front hemisphere and rear hemisphere hemisphere and rear hemisphere (good for stage-floor miking(good for stage-floor miking

More isolation than cardioidMore isolation than cardioid Less reverb than cardioidLess reverb than cardioid

Microphone: SupercardioidMicrophone: Supercardioid

Microphone: Hyper-cardioidMicrophone: Hyper-cardioid

Maximum side rejectionMaximum side rejection Maximum isolation – maximum Maximum isolation – maximum

rejection of reverb, leakage, and rejection of reverb, leakage, and background noisebackground noise

Microphone: HypercardioidMicrophone: Hypercardioid

Microphone: Bi-directionalMicrophone: Bi-directional

Also called figure-8Also called figure-8 Front and rear pickup, with sides Front and rear pickup, with sides

rejectedrejected Across table interviews, two-part Across table interviews, two-part

vocals/instrumentalsvocals/instrumentals

Microphone: Bi-directionalMicrophone: Bi-directional

MicrophonesMicrophones

Frequency response varies from Frequency response varies from proximity: off axis colorationproximity: off axis coloration

Off axis coloration: mic will have a Off axis coloration: mic will have a different tone quality on and off axisdifferent tone quality on and off axis

Microphones: Microphones:

Condensers or Dynamics come in all Condensers or Dynamics come in all polar patterns (except bi-directional polar patterns (except bi-directional dynamic)dynamic)

End-addressed or side addressedEnd-addressed or side addressed Switchable polar patterns common Switchable polar patterns common

with side addressed micswith side addressed mics Boundary mics: half pattern (usually Boundary mics: half pattern (usually

omni); rejects room acousticsomni); rejects room acoustics

Boundary MicrophoneBoundary Microphone

Microphones: Frequency Microphones: Frequency ResponseResponse

Range of frequencies a mic will reproduce Range of frequencies a mic will reproduce at an equal level (within a tolerance like at an equal level (within a tolerance like ±3db)±3db)– Most instruments: 80Hz – 15kHzMost instruments: 80Hz – 15kHz– Bass instruments: 40Hz - 9kHzBass instruments: 40Hz - 9kHz– Brass and voice: 80 Hz – 12kHzBrass and voice: 80 Hz – 12kHz– Piano: 40 Hz – 12 kHzPiano: 40 Hz – 12 kHz– Cymbals and some percussion: 300 Hz – 15 or Cymbals and some percussion: 300 Hz – 15 or

20 kHz20 kHz– Orchestra or symphonic band: 40 Hz – 15kHzOrchestra or symphonic band: 40 Hz – 15kHz

Microphones: Frequency Microphones: Frequency ResponseResponse

Roll-off switches: attenuates frequencies Roll-off switches: attenuates frequencies below a point below fundamental below a point below fundamental frequency of instrument you’re recording frequency of instrument you’re recording (guitar does not play below 80 Hz)(guitar does not play below 80 Hz)

Frequency response curveFrequency response curve Presence peak: rising high end around 5 – Presence peak: rising high end around 5 –

10kHz makes sounds more crisp and 10kHz makes sounds more crisp and articulate (crunchy)articulate (crunchy)

Proximity effect: a bass boost tendency of Proximity effect: a bass boost tendency of a mic when placed too close. a mic when placed too close.

Microphones: Other ratingsMicrophones: Other ratings

ImpedanceImpedance Maximum SPL: the point at which a mic Maximum SPL: the point at which a mic

starts to distort – 125db good, 135db better, starts to distort – 125db good, 135db better, 150db excellent150db excellent

Sensitivity: how much output voltage a mic Sensitivity: how much output voltage a mic produces when driven by a certain SPLproduces when driven by a certain SPL

Self-noise: noise level or hiss a mic producesSelf-noise: noise level or hiss a mic produces Signal to Noise Ratio: the difference in Signal to Noise Ratio: the difference in

decibels between mic’s sensitivity and it’s decibels between mic’s sensitivity and it’s self noiseself noise

Microphone typesMicrophone types

Large-Diaphragm CondenserLarge-Diaphragm Condenser– Good low frequency response and low self-noiseGood low frequency response and low self-noise

Small-Diaphragm CondenserSmall-Diaphragm Condenser– Stick shaped or pencil, usually cardioid and end Stick shaped or pencil, usually cardioid and end

addressed, good transient response and detail, addressed, good transient response and detail, good for acoustic instrumentsgood for acoustic instruments

Dynamic InstrumentDynamic Instrument– Stick shaped, end addressed, be careful of Stick shaped, end addressed, be careful of

presence peak, used on drums and guitar ampspresence peak, used on drums and guitar amps

Microphone typesMicrophone types

Live-VocalLive-Vocal– Ice cream cone shaped large grill to Ice cream cone shaped large grill to

reduce breath pops, can be condenser, reduce breath pops, can be condenser, ribbon, or dynamic, usually has ribbon, or dynamic, usually has presence peak and low frequency roll-offpresence peak and low frequency roll-off

Boundary MicBoundary Mic– Used on surfaces like piano lid, wall, Used on surfaces like piano lid, wall,

picks up direct and reflected sound at picks up direct and reflected sound at the same time for smooth responsethe same time for smooth response

Microphone typesMicrophone types

Miniature MicMiniature Mic Stereo Mic: combines two directional Stereo Mic: combines two directional

mic capsules in a single housingmic capsules in a single housing Digital (USB) Mic – built-in a/d Digital (USB) Mic – built-in a/d

converterconverter

Microphone SelectionMicrophone Selection

Natural, smooth tone Natural, smooth tone qualityquality

Flat frequency Flat frequency responseresponse

Bright, present tone Bright, present tone qualityquality

Presence peak (5kHz)Presence peak (5kHz)

Extended lowsExtended lows Omni condenser Omni condenser dynamic with dynamic with extended low extended low frequency responsefrequency response

Extended highsExtended highs condensercondenser

Choosing a MicrophoneChoosing a Microphone

Boosted bass up Boosted bass up closeclose

Directional micDirectional mic

Reduced leakage, Reduced leakage, reduced room reduced room acousticsacoustics

DirectionalDirectional

Enhanced acousticEnhanced acoustic OmniOmni

Miking close to a Miking close to a surfacesurface

Boundry (TMZ)Boundry (TMZ)

Choosing a MicChoosing a Mic

Coincident or near-Coincident or near-coincidentcoincident

Stereo micStereo mic

Extra ruggednessExtra ruggedness DynamicDynamic

Distortion-free pick-Distortion-free pick-up of loud soundsup of loud sounds

Condenser with high Condenser with high SPL spec or dynamicSPL spec or dynamic

Low self-noise, high Low self-noise, high sensitivity, noise-free sensitivity, noise-free pickup of quiet pickup of quiet soundssounds

Large-diaphragm Large-diaphragm condenser miccondenser mic

Mic AccessoriesMic Accessories

Pop Filter: breath pops “p”, “b”, or Pop Filter: breath pops “p”, “b”, or “t” sounds“t” sounds

Stands and boomsStands and booms Shock MountShock Mount SnakeSnake