speakers &...

Speakers & Microphones

Lecture 16

Saturday, March 20, 2010

Frequency Response (FR)


electricaltransducers

How accurately does a transducer convert wave information from one state to another?

mechanical



Flat FR - the transducer accurately translates wave information across the entire spectrum.

Colored FR - the transducer introduces changes to the wave information at certain points across the spectrum

All transducers introduce change, and are somewhat colored. These terms are used for comparison, not for categories.




Generally speaking, a flat FR is ...


• More desirable




• More desirable

• Harder to manufacture




• More desirable

• Harder to manufacture

• More expensive




Measuring FR



White noise (audio wave with equal energy at all frequencies) is sent into a transducer, and the resulting wave that comes out is measured. The resulting difference is a measurement of FR.

Measuring FR



analyze these FR graphs


Speakers vs. Monitors


Speakers - built for live use, built to produce volume, flat FR is important, but not the primary focus.



Monitors - built for studio use, built for accuracy, flat FR. Volume is not the primary purpose.



Why is a flat FR critical in the studio?


Why does a flat FR matter in the upper frequency range (6k and above)?


< geek-out >


< geek-out >

Flat FR ≠ always most expensive


< geek-out >

Flat FR ≠ always most expensiveSome transducers are inaccurate, but in a highly musical way (U87, Ribbon)


< geek-out >

Flat FR ≠ always most expensiveSome transducers are inaccurate, but in a highly musical way (U87, Ribbon) mics and preamps more than speakers


< geek-out >


Musical in what way?


< geek-out >


Musical in what way?(1) Fletcher-Munson Curve, inaccuracy of the ear


< geek-out >


Musical in what way?(1) Fletcher-Munson Curve, inaccuracy of the ear(2) Matches overtones / timbre of the musical source


< geek-out >


Musical in what way?(1) Fletcher-Munson Curve, inaccuracy of the ear(2) Matches overtones / timbre of the musical source(3) Matches FR of other pieces of gear in the chain


< geek-out >


Musical in what way?(1) Fletcher-Munson Curve, inaccuracy of the ear(2) Matches overtones / timbre of the musical source(3) Matches FR of other pieces of gear in the chain

< /geek-out >


Microphones


Dynamic, Condenser, Ribbon


Dynamic, Condenser, Ribbon

Function UseConstruction


Dynamic


DynamicShure SM58


DynamicShure SM58Cost: $99


DynamicShure SM58Cost: $99Range: $50-$200


DynamicShure SM58Cost: $99Range: $50-$200

Construction: diaphragm attached to a conductive coil. Pressure changes move the coil back and forth through the magnetic field of a permanent magnet, inducing changes in the current through the coil.


Dynamic


DynamicPros:


DynamicPros: - rugged construction, stands up well to hard use, even abuse


DynamicPros: - rugged construction, stands up well to hard use, even abuse - handles high sound pressure levels (spl) without distortion



Cons:



Cons: - Inaccurate FR, loss of high and low frequencies



Cons: - Inaccurate FR, loss of high and low frequencies - slow transient response



Cons: - Inaccurate FR, loss of high and low frequencies - slow transient response - narrow pickup range


Dynamic


DynamicUses:


DynamicUses:

Live audio


DynamicUses:

Live audioguitar amps


DynamicUses:

Live audioguitar ampssnare drums, other loud percussion


Condenser


CondenserNeumann U87


CondenserNeumann U87Cost: $2650


CondenserNeumann U87Cost: $2650Range: $300 - $10,000


CondenserNeumann U87Cost: $2650Range: $300 - $10,000

Construction: Diaphragm moves closer and further from a charged backplate, alternately drawing current into, and pushing current out of, the backplate.


Condenser


CondenserPros:


CondenserPros:- accurate FR


CondenserPros:- accurate FR- great high frequency clarity


CondenserPros:- accurate FR- great high frequency clarity- wide pickup range



Cons:



Cons:- fragile!



Cons:- fragile!- expensive



Cons:- fragile!- expensive- high SPLs can cause damage



Cons:- fragile!- expensive- high SPLs can cause damage- requires external power supply


Condenser


CondenserUses:


CondenserUses:

Studio recording, especially for voca l s or wooded acous t i c instruments


CondenserUses:

Studio recording, especially for voca l s or wooded acous t i c instruments

Live use for drum overheads, orchestral sections


Ribbon


RibbonRoyer 121


RibbonRoyer 121Cost: $1095


RibbonRoyer 121Cost: $1095Range: $600 - $3500


RibbonRoyer 121Cost: $1095Range: $600 - $3500

Construct ion : A corrugated conductive ribbon moves back and forth through the field of a magnet, causing a change in induction in the ribbon.


Ribbon


RibbonPros:


RibbonPros:- Added resonance


RibbonPros:- Added resonance- Enhanced midrange overtones, slight high freq. rolloff


RibbonPros:- Added resonance- Enhanced midrange overtones, slight high freq. rolloff- Introduces added “warmth” to the sound



Cons:



Cons:- not accurate FR


Ribbon


RibbonUses:


RibbonUses:

Resonating instruments (acoustic guitar, strings, piano), especially in darker, classical settings.


RibbonUses:

Resonating instruments (acoustic guitar, strings, piano), especially in darker, classical settings.

Voice, especially where enhanced midrange overtones and high roll-off will help.


Ribbon“To Ramona” by Bob Dylanpiano by Michael Lee

Recorded on a Yamaha C7 in the “A” room of Citrus Studios, using a Coles 4038 Ribbon Mic.


CondenserRibbon“To Ramona” by Bob Dylanpiano by Michael Lee

Recorded on a Yamaha C7 in the “A” room of Citrus Studios, using a Coles 4038 Ribbon Mic.

“Ring Them Bells”by Bob Dylan

piano by Michael Lee

Recorded in the same room, on the same

piano, using an AKG C12 condenser mic


pickup patterns


Pickup Patterns

Cardioid


Pickup Patterns

Hyper-Cardioid


Pickup Patterns

Bi-Directional(or Figure 8)


Pickup Patterns

Omni


Pickup Patterns

Shotgun


What you should know



• Vocabulary: Frequency Response (FR), Sound Pressure Level (SPL), Transient Response, White noise




• Speaker vs. Monitors: purpose and use





• Microphones, by type






• Construction > function > use






• Construction > function > use

• Pickup Patterns


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