Information AboutTweeter |
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OVERVIEW A tweeter is a Loudspeaker that produces high frequencies. The range of frequencies is typically from around 2,000 Hertz to 22,000 hertz (20,000 Hz is generally considered to be the upper limit of the human ear). Some tweeters can reach up to even 30-35kHz. Tweeter placement can be critical since the high frequencies are much more directional than the lower frequencies handled by a Woofer . This requires the tweeter face to be directed towards the listener. TYPES OF TWEETERS Cone tweeter Cone tweeters have the same basic form as that of a Dynamic Speaker driver with optimisations to operate at higher frequencies. The optimisations are as follows:
Dome tweeter A dome tweeter is constructed by coupling a light voice coil to a light dome (made of coated cloth, thin metal or other suitable material) which is attached to the magnet or the top-plate with a rigid suspension. This tweeter typically does not have a frame or basket. Piezo tweeter A Piezo tweeter contains a piezo-electric crystal as the transducer. It operates by the flexing of the crystal in response to the voltage applied across the crystal's surfaces. The flexation is the mechanical analog of the electrical signal impressed upon the crystal and thus the crystal converts electrical energy into mechanical (and hence acoustic) energy. The piezo tweeter does not use magnetism to operate and does not contain a magnet. Horn tweeter A horn tweeter is any of the above tweeters coupled to a flare or Horn . The horn improves the off-axis response of the tweeter by aiding in greater dispersion (reducing directivity) of the tweeter. It also improves the efficiency of the tweeter by coupling the relatively high acoustic impedance of the driver, to the lower impedance of the air. Ribbon tweeter ribbon tweeter.]] A Ribbon Tweeter uses a piece of very thin aluminium foil suspended in a powerful magnetic field to reproduce high frequencies. The development of ribbon tweeters has followed the development of Ribbon Microphone s. High power versions of ribbon tweeters are becoming common in large scale sound reinforcement line array systems, that can serve audiences of thousands. This is because the ribbon tweeter exhibits specific directional properties, with very wide horizontal dispersion (coverage) and very tight vertical dispersion. These properties mean that the devices can be stacked vertically, making a high frequency line array that will project high sound pressure levels much further than conventional tweeters. Some manufacturers have opted to make wave guides that channel the hemispherical output of a regular tweeter into a more focused beam, approximating a ribbon tweeter. However this approach doesn't yield the same output as a true ribbon, which will almost always have a better high frequency response than a standard tweeter. This is because the entire ribbon is immersed in its magnetic field, whereas a standard dome or cone tweeter has only its voice coil coupled to its magnetic field. This leads to failure of the dome or cone to faithfully track voice coil movement, creating phase distortion called breakup. Ribbons will function at higher frequencies than conventional circular tweeters, without breakup modes (distortion). An electrostatic tweeter operates on the same principles as a full-range electrostatic speaker or a pair of electrostatic headphones. This type of speaker employs a front and back element with holes in it on which positive and negative electrostatic charges have been placed. The output of the amp goes to a thin piece of metallized mylar which then pulsates with the music. Electrostatics have no even-order harmonic distortion because of their push-pull design. They also have no phase distortion. The design has endured for decades, but because of high cost and inefficiency is not widely used. SEE ALSO |
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