Electronic Crossover

Please 'Boom' Responsibly As most of you have noticed, the noise ordinances have become much tougher lately. Most of this is due to idiots, yes IDIOTS, who drive through residential areas with their windows down while their system is playing at full power. To make things worse, the music they listen to has all sorts of foul language that's not suitable for small children, (who may be playing outside). There are even a few people, who are even beyond idiot status, that play their systems at full power through residential areas after 10:00 PM (when many people go to bed). I don't believe that this type of behavior is good for the industry. If the fines get too stiff, people will stop buying large systems. If this happens, more people will get out of car audio (who wants a mediocre system). People get interested in things because they're exciting. A deck and four 6.5" speakers are not going to interest many of the younger car audio enthusiasts. If car audio enthusiasts keep annoying more and more people, the fines will keep getting tougher. All of this will only reduce interest in the equipment that fuels the industry. If you want to listen to your system at full volume, get out on the highway where there's little chance of bothering anyone. When you get to a red light, turn it down. If the only thing attractive about you is your 'system', you have some work to do. Bottom line... Think about what you're doing. Think about other people. It's not the end of the world if you have to turn the volume down for a little while.

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.

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3200Hz

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