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A passive crossover A bi-amplified system with an active crossover Used in multi-driver speaker systemsthe crossover is an assembly of filters that separate the input signal into different frequency ranges i. Hence the drivers receive power only at their operating frequency the sound frequency range they were designed forthereby reducing distortion in the drivers and interference between them.
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The ideal characteristics of a crossover may include perfect out-of-band attenuation at the output of each filter, no amplitude variation "ripple" within each passband, no phase delay between overlapping frequency bands, to name just a few.
Crossovers can be passive or active. A passive crossover is an electronic circuit that uses a combination of one or more resistorsinductors, or non-polar capacitors.
These components are combined to form a filter network and are most often placed between the full frequency-range power amplifier and the loudspeaker drivers to divide the amplifier's signal into the necessary frequency bands before being delivered to the individual drivers. Passive crossover circuits need no external power beyond the audio signal itself, but have some disadvantages: they may require larger inductors and capacitors due to power handling requirements being driven by the amplifierlimited component availability to optimize the crossover's characteristics at such power levels, etc.
Unlike active crossovers which include a built-in amplifier, passive crossovers have an inherent attenuation within the passband, typically leading to a reduction in damping factor before the voice coil  An active crossover is an electronic filter circuit that divides the signal into individual frequency bands before power amplification, thus requiring at least one power amplifier for each bandpass.
Any technique that uses crossover filtering followed by amplification is commonly known as bi-amping, tri-amping, quad-amping, and so on, depending on the minimum number of amplifier channels.
In car audio systems, passive crossovers may be in a separate box, necessary to accommodate the size of the components bélféreg emberben tünetek. Passive crossovers may be simple for low-order filtering, or complex to allow steep slopes such as 18 or 24 dB per octave. Passive crossovers can also be designed to compensate for undesired characteristics of driver, horn, or enclosure resonances,  and can be tricky to implement, due to mérgezett olcsó interaction.
The changes are matters of concern for many in the hi-fi world.
Active crossovers may be simple circuits that emulate the response of a passive network, or may be more complex, allowing extensive audio adjustments.
Some active crossovers, usually digital loudspeaker management systems, may include electronics and controls for precise alignment of phase and time between frequency bands, equalization, dynamic range compression and limiting control. The cabinet is narrow to raise the frequency where a diffraction effect called the "baffle step" occurs. Most loudspeaker systems consist of drivers mounted in an enclosureor cabinet.
The role of the enclosure is to prevent sound waves emanating from the back of a driver from interfering destructively with those from the front. The sound waves emitted from the back are ° out of phase with those emitted forward, so without an enclosure they typically cause cancellations which significantly degrade the level and quality of sound at low frequencies.
The simplest driver mount is a flat panel i. However, in this approach, sound frequencies with a wavelength longer than the baffle dimensions are canceled out, because the antiphase radiation from the rear of the cone interferes with the radiation from the front. With an infinitely large panel, this interference could be entirely prevented.
A sufficiently large sealed box can approach this behavior.
A sealed enclosure prevents transmission of the sound emitted from the rear of the loudspeaker by confining the sound in a rigid and airtight box. Techniques used to reduce transmission of sound through the walls of the cabinet include thicker cabinet walls, lossy wall material, internal bracing, curved cabinet walls—or more rarely, visco-elastic materials e.
However, a rigid enclosure reflects sound internally, which can then be transmitted back through the loudspeaker diaphragm—again resulting in degradation of sound quality. This can be reduced by internal absorption using absorptive materials often called "damping"such as glass woolwool, or synthetic fiber batting, within the enclosure. The internal shape of the enclosure can also be designed to reduce this by reflecting sounds away from the loudspeaker diaphragm, where they may then be absorbed.
Other enclosure types alter the rear sound radiation so it can add constructively to the output from the front of the cone. Egyéb paraziták az időbeli bambuszrostból that do this including bass reflexpassive radiator, transmission line, etc. To make the transition between drivers as seamless as possible, system designers have attempted to time-align or phase adjust the drivers by moving one or more driver mounting locations forward or back so that the acoustic center of each driver is in the same vertical plane.
This may also involve tilting the face speaker back, providing a separate enclosure mounting for each driver, or less commonly using electronic techniques to achieve the same effect. These attempts have resulted in some unusual cabinet designs.
The speaker mounting scheme including cabinets can also cause diffractionresulting in peaks and dips in the frequency response. The problem is usually greatest at higher frequencies, where wavelengths are similar to, or smaller than, cabinet dimensions.
The effect can be minimized by rounding the front edges of the cabinet, curving the cabinet itself, using a smaller or narrower enclosure, choosing a strategic driver arrangement, using absorptive material around a driver, or some combination of these and other schemes. Horn loudspeakers[ edit ] A three-way loudspeaker that uses horns in front of each of the three drivers: a shallow horn for the tweeter, a long, straight horn for mid frequencies and a folded horn for the woofer Main article: Horn loudspeaker Horn loudspeakers are the oldest form of loudspeaker system.
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The use of horns as voice-amplifying megaphones dates at least to the 17th century,  and horns were used in mechanical gramophones as early as Horn loudspeakers use a shaped waveguide in front of or behind the driver to increase the directivity of the loudspeaker and to transform a small diameter, high pressure condition at the driver cone surface to a large diameter, low pressure condition at the mouth of the horn.
The size of the throat, mouth, the length of the horn, as well as the area expansion rate along it must egyéb paraziták az időbeli bambuszrostból carefully chosen to match the drive to properly provide this transforming function over a range of frequencies every horn performs poorly outside its acoustic limits, at both high and low frequencies.
The length and cross-sectional mouth area required to create a bass or sub-bass horn require a horn many feet long.
Some horn designs not only fold the low frequency horn, but use the walls in a room corner as an extension of the horn mouth. In the late s, horns whose mouths took up much of a room wall were not unknown amongst hi-fi fans.
Room sized installations became much less acceptable when two or more were required. A horn loaded speaker can have a sensitivity as high as dB at 2. This is a hundredfold increase in output compared to a speaker rated at 90 dB sensitivity, egyéb paraziták az időbeli bambuszrostból is invaluable in applications where high sound levels are required or amplifier power is limited.
Transmission line loudspeaker[ edit ] Main article: Transmission line loudspeaker A transmission line loudspeaker is a loudspeaker enclosure design which uses an acoustic transmission line within the cabinet, compared to the simpler enclosures used by sealed closed or ported bass reflex designs. Instead of reverberating in a fairly simple damped enclosure, sound from the back of the bass speaker is directed into a long generally folded damped pathway within the speaker enclosure, which allows far greater control and use of speaker energy and the resulting sound.
Two-way binding posts on a loudspeaker, connected using banana plugs. A 4-ohm loudspeaker with two pairs of binding posts capable of accepting bi-wiring after the removal of two metal straps. Most home hi-fi loudspeakers use two wiring points to connect to the source of the signal for example, to the audio amplifier or receiver.
To accept the wire connection, the loudspeaker enclosure may have binding postsspring clips, or a panel-mount jack.
This typically causes monophonic material in a stereo recording to be canceled out, reduced in orrcseppek a parazitáktól, and made more difficult to localize, all due to destructive interference of the sound waves.
The cancellation effect is most noticeable at frequencies where the loudspeakers are separated by a quarter wavelength or less; low frequencies are affected the most.
This type of miswiring error does not damage speakers, but is not optimal for listening. Higher-priced and higher powered sound system cabinets and instrument speaker cabinets often use Speakon connectors.
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