Electronic Crossover:
A crossover is a filter. It is used to block some frequencies while allowing others to pass with little or no effect. An electronic crossover is a set of active filters which pass/reject part of the audio band. The crossover point is determined by changing the value of resistors and/or capacitors in the active filter circuit. A high pass crossover will allow frequencies above a predetermined point to pass. The frequencies below the crossover point will rolloff at a rate determined by the crossover's design. A low pass crossover would let low frequencies pass while reducing the level of the high frequency part of the signal. The signal from the head unit feeds the crossover. The signal leaving the crossover goes to an amplifier. If the high pass output is connected to an amplifier, that amplifier would be connected to smaller speakers which may include tweeters. A low pass xover would drive an amp connected to larger speakers, including woofers.
The image below shows how the level of the audio signal rolls off after passing through different types of crossovers.
Graph Legend:
|
Cyan
|
=
|
6dB/octave
|
|
Red
|
=
|
12dB/octave
|
|
Green
|
=
|
18dB/octave
|
|
Violet
|
=
|
24dB/octave
|
|
|
Put your mouse/cursor over the crossover frequencies to the left of the graph to see how the slope slides (to pass varying amounts of the audio spectrum) as you change the crossover point. The frequencies that fall on the flat part of the 'curve' are passed without any change in their output level. The part of the audio band that falls on the slope of the curve have their output reduced. Their output level is reduced in proportion to the point where they fall on the curve. If they fall on the higher part of the slope, the output is higher than those frequencies that fall on the lower parts of the slope.
|
