1 output transducers (loudspeakers). 2 loudspeakers transducers that convert electrical signals...
Post on 15-Jan-2016
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Output Transducers
Output Transducers
(Loudspeakers)
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LoudspeakersLoudspeakers
Transducers that convert electrical signals into sound waves
The current flow in the coil causes the diaphragm to move, thus causing changes in sound pressure
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LoudspeakersLoudspeakers
Loudspeakers usually consist of multiple speakers (drivers) to cover the full frequency range
Tweeter
Mid-range
Woofer
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WooferWoofer
Produces Low Frequencies
Cone diaphragmSurround
Basket Spider
Magnet
Voice Coil
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Woofer Frequency ResponseWoofer Frequency Response
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TweeterTweeter
Produces high frequenciesUses only one suspension medium.
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Tweeter Frequency Response
Tweeter Frequency Response
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CrossoverCrossover
Divides and routes the appropriate portions of the signal to each of the speakers in the system
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Crossover High-PassCrossover High-Pass
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Crossover Low-PassCrossover Low-Pass
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Crossover Band-PassCrossover Band-Pass
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Passive CrossoverPassive Crossover
A passive filter is placed after the amplifier
It cannot raise the gain on the signal
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Active FilterActive Filter
An active filter is so called because it requires electric power for its operation and can raise the gain of the signal
enables adjustment of the frequency ranges
In active filtering the signal splitting occurs before it is amplified
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Passive SpeakersPassive Speakers
These do not contain an in-built amplifier and so must be powered by an external ampUsed in most home Hi-Fi systemsDo not require power leadsMay require fairly thick cables to carry the
signal
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Active SpeakersActive Speakers
Have a built in amplifier and so can be used with small output signalsMost PC speakers are active to boost the
weak output (~4W) from most sound cardsRequire only thin signal cablesIncreased weightOverall performance my be restricted by a
poor amplifier
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DistortionDistortion
Distortion is an unwanted change introduced in the original sound when it is reproduced through a loudspeaker system
Intermodulation distortion• the interaction of two or more frequencies
contained in the original sound which produces a third frequency not present in the original sound
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DistortionDistortion
Harmonic distortion• similar to intermodulation distortion, except
it is a reaction involving one frequency Transient distortion
• the inability of a loudspeaker system to properly reproduce transients, short, temporary sounds of less than a second
Loudness distortion• caused by overdriving the loudspeaker
system, producing a loudness level higher than that of the original studio production
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EnclosuresEnclosures
The loudspeaker enclosure serves as a passive processor of the sound, collecting and directing it to the desired location
Without a baffle or enclosure low frequency sound from the front and back of the speaker will cancel each other out
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Infinite BaffleInfinite Baffle
By completely enclosing the back of the speaker we get an infinite degree of blockingStops low frequency
cancellationWastes energy produced by
rear of speaker
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Vented Enclosure (Bass-reflex)
Vented Enclosure (Bass-reflex)
The rear wave from the loudspeaker is delayed so that it emerges from the port in phase with the wave motion from the front
Relies on strict relationship Enclosure sizeSize of opening (port)Resonance of loudspeaker
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FinFin
Fin
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