Editing Audio crossover (section)

{{Short description|Electronic filter circuitry used in loudspeakers}}
{{Use American English|date=January 2022}} 

[[File:B-W Matrix3MkII FotoWeiche.jpg|thumb|250px|A passive 2-way crossover designed to operate at [[loudspeaker]] voltages.]]

'''Audio crossovers''' are a type of [[electronic filter]] circuitry that splits an audio signal into two or more frequency ranges, so that the signals can be sent to loudspeaker drivers that are designed to operate within different frequency ranges. The crossover filters can be either [[Passivity (engineering)|active or passive]].<ref name="AshleyKaminsky1971" /> They are often described as ''two-way'' or ''three-way'', which indicate, respectively, that the crossover splits a given signal into two frequency ranges or three frequency ranges.<ref name="Caldwell2013" /> Crossovers are used in [[loudspeaker]] [[Speaker enclosure|cabinets]], [[power amplifier]]s in [[consumer electronics]] ([[hi-fi]], [[home cinema]] sound and [[car audio]]) and [[pro audio]] and musical instrument amplifier products. For the latter two markets, crossovers are used in [[bass amplifier]]s, [[keyboard amplifier]]s, bass and keyboard speaker enclosures and [[sound reinforcement system]] equipment (PA speakers, monitor speakers, [[subwoofer]] systems, etc.). 

Crossovers are used because most individual [[loudspeaker driver]]s are incapable of covering the entire [[audio spectrum]] from low frequencies to high frequencies with acceptable relative volume and absence of [[distortion]]. Most [[hi-fi]] speaker systems and sound reinforcement system speaker cabinets use a combination of multiple loudspeaker drivers, each catering to a different [[frequency band]]. A standard simple example is in hi-fi and PA system cabinets that contain a [[woofer]] for low and mid frequencies and a [[tweeter]] for high frequencies. Since a sound signal source, be it recorded music from a [[CD player]] or a live band's mix from an [[audio console]], has all of the low, mid and high frequencies combined, a crossover circuit is used to split the audio signal into separate frequency bands that can be separately routed to loudspeakers, tweeters or horns optimized for those frequency bands. 

Passive crossovers<ref name="Thiele1997" /> are probably the most common type of audio crossover. They use a network of passive electrical components (e.g., capacitors, inductors and resistors) to split up an amplified signal coming from one [[power amplifier]] so that it can be sent to two or more loudspeaker drivers (e.g., a [[woofer]] and a very low frequency [[subwoofer]], or a woofer and a [[tweeter]], or a woofer-midrange-tweeter combination).

Active crossovers are distinguished from passive crossovers in that they split up an audio signal prior to the power amplification stage so that it can be sent to two or more power amplifiers, each of which is connected to a separate loudspeaker driver.<ref name="Allen1974" /><ref name="Caldwell2013" /> [[Home cinema]] [[5.1 surround sound]] audio systems use a crossover that separates out the very-low frequency signal, so that it can be sent to a [[subwoofer]], and then sending the remaining low-, mid- and high-range frequencies to five speakers which are placed around the listener. In a typical application, the signals sent to the surround speaker cabinets are further split up using a passive crossover into a low/mid-range woofer and a high-range tweeter. Active crossovers come in both digital and analog varieties.  

Digital active crossovers often include additional signal processing, such as limiting, delay, and equalization. Signal crossovers allow the audio signal to be split into bands that are processed separately before they are mixed together again. Some examples are [[multiband compression]], [[Audio level compression#Limiting|limiting]], [[de-essing]], multiband [[distortion]], bass enhancement, high frequency exciters, and [[Audio noise reduction|noise reduction]] such as [[Dolby noise reduction system|Dolby A noise reduction]].