Speaker,

3} Speaker:

Speaker is an output device which is used to produce audio. It convert analog audio signals to its equivalent audio sound. The sound produced by speaker is dependent upon there frequency and amplitude. Frequency determines how low or high pitch of sound is while Amplitude determines the loudness of sound.

When computer were initially released, they had on-board speakers built into the chassis that generated a sound like tones and beeps. The very first loudspeaker was built when telephone system were developed in the late 1800s.But it was in 1912 that loudspeakers really became practical. By the 1920’s they were used in radios, phonographs, public address systems and also in theater sound systems for talking motion pictures. On the other hand the first internal computer speaker was built by IBM in 1981 and produced basic low quality sound.

The first external computer speaker was built by Abinawan Purachidas in 1991 and are still the dominant type of speaker for computers.

                                                                                                                   

A)  Dynamic Speaker: The most widely used type of speaker is the dynamic speaker, invented in 1925 by Edward W. Kellogg and Chester W. Rice. These devices are typically passive speakers. They are generally have one or more woofer driver to produce low-frequency sound, which is also known as bass. It has the midrange audio to the midrange driver and the low-frequency material to the larger woofers. Professional audio dynamic speakers that offer higher performance may also have drivers on the rear of the speaker enclosure to further amplify sound.  A mid-range speaker is a loudspeaker driver that reproduces a band of frequencies generally between 1–6 kHz, otherwise known as the 'mid' frequencies (between the woofer and tweeter).

 

dynamic-speaker-sub-woofer-close-up

B)   Subwoofer Speaker: Subwoofer are one-driver dynamic loudspeaker with a single woofer driver. These are also used to transmit bass or low-frequency Sound. The first subwoofer was developed in the 1960’s to add bass response to home stereo system. It get greater popularity in the consciousness in the 1970’swith the introduction of Sensurround  in movies such as Earthquake, which produced loud low-frequency sounds through large subwoofers. The range of subwoofers is about 20-200 Hz for consumer products below 100 Hz for professional live sound , and below 80Hz in THX-approved system.

 

JBL-CS1200WSI-1200-Watt-Subwoofer-SDL040542140-1-287b6

C)  Horn Speaker: A horn was the one of the earliest form of speaker.A horn speaker or loudspeaker is that which increases its overall efficiency by the use of Acoustic horn. An acoustic horn converts large pressure variations with a small displacement area into a low pressure variation with a large displacement area and vice versa. Thomas Edison, Magnavox, and Victrola all developed advanced and well-performing horns from 1880 to the 1920's. The main advantage of horn loudspeakers is they are more efficient; they can typically produce 10 times (10 dB) more sound power than a cone speaker from a given amplifier output. A common form (right) consists of a compression driver which produces sound waves with a small metal diaphragm vibrated by an electromagnet, attached to a horn, a flaring duct to conduct the sound waves to the open air. Another type is a woofer driver mounted in a loudspeaker enclosure which is divided by internal partitions to form a zigzag flaring duct which functions as a horn; this type is called a folded horn speaker.

                         

iphone-bugle-horn-speaker-4

PA Horn Speaker - 8

D)  Electrostatic Speaker: An  electrostatic loudspeaker (ESL) is a loudspeaker design in which sound is generated by the force exerted on a membrane suspended in an  electrostatic field. One thing common to electrostatic loudspeaker designs is the use of extremely high voltage. Electrostatic loudspeakers make use of a large, thin metal plate between two parallel screens. An amplified audio signal is impressed onto the screens, polarizing the metal sheet, and the resulting electrostatic force creates a motion of the sheet, producing a sound wave. Electrostatic speakers function well at high frequencies, but they are unable to move enough air to perform well at low frequencies and often require somewhat greater power than electromagnetic speakers. On the output side of the transformer, a very high voltage is applied, and this is what generates the electric field that eventually moves the speaker’s diaphragm and makes music. Arthur Janszen was granted U.S. Patent 2,631,196 in 1953 for an electrostatic loudspeaker. They can typically produce frequency from 24-30,000Hz and ± 3 dB With Active Dynamic Equalisation below 50 Hz.

MARTIN LOGAN CLASSIC ESL 9 ELECTROSTATIC SPEAKERS

E)   Planar Magnetic Speaker: These speakers feature a tall, thin, and narrow metal ribbon instead of the wide diaphragms found on electrostatic speakers. Rather than charged metal panels like those found on electrostatic speakers, the ribbon in a planar-magnetic speaker is suspended between powerful magnets. A current passes through the metal ribbon, which resonates towards or away from the magnets in order to generate sound waves.  The advantage of a ribbon driver is that the ribbon has very little mass; thus, it can accelerate very quickly, yielding very good high-frequency response. This type of speaker does not need to be connected to an electrical system to operate. Planar magnetic transducers offer numerous benefits like Responsiveness, Frequency and Distortion, Durability, Amplifier Friendly.

Magnepan MMG Full-Range Planar-Magnetic speaker system

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