Wednesday, February 18, 2009

Design of Unconventional Speakers

Horn loudspeaker:

This is the oldest type of speaker used and was first incorporated with cylinder recording players. They used a waveguide to increase the directivity of the speaker and propagate the high pressure at one end of the speaker to a larger area at the other end of the speaker; this increases the speaker sensitivity. The design of the speaker like the throat size, mouth diameter and the horn length must be carefully chosen to get maximum frequency response.


Piezoelectric speakers:

These speakers are usually incorporated in the watches as beepers and also as tweeters in cheap systems like radio and computer speakers. Some of the advantages the Piezoelectric speakers have over conventional horn loudspeaker are: they can withstand high frequencies, and their electrical property permits them to work without crossover. Some of the disadvantages of Piezoelectric speakers are: there is a possibility of amplifiers to oscillate and damage itself when capacitive loads like Piezoelectric speakers are present, and their frequency response is much less when compared to other speakers.


Electrostatic speakers:

These speakers are driven by high voltage electric field. It consists of a thin, charged membrane and the electric field drives the membrane. They have few disadvantages like low efficiency, and it attracts dust particles as its membrane holds static charges.


Ribbon and Planar Magnetic speakers:

The ribbon magnetic speaker consists of a thin ribbon made of metal which is suspended in a magnetic field. When an electrical signal is made to pass through the ribbon the ribbon moves to make sound. They have the advantage of giving good frequency response for high frequencies, but they are extremely fragile and they are costly to construct as it requires a very powerful magnet.


Planar magnetic speakers are speakers made up of a coil and a stretchy membrane. When current is passed through the coil the magnetic field of the coil interacts with the field of the magnets present around the membrane which will vibrate the membrane.

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