What is a crossover?
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drstawl
Banned
No- seriously- it's a network of (usually passive) components (caps) in a multi-driver speaker that divides where various frequency components of a signal are sent.
Some drivers are designed to reproduce low frequency signals so the crossover splits off those frequencies from the whole signal and sends them to the low frequency driver. Same with the mids and highs in a 2 or three-way system.
Some drivers are designed to reproduce low frequency signals so the crossover splits off those frequencies from the whole signal and sends them to the low frequency driver. Same with the mids and highs in a 2 or three-way system.
sonusman
Banned
There are actually two types of crossovers, active and passive. They are very different in how they work.
Passive crossovers are usually installed in the speaker box. A capasitor and a coil are used in tandem to split the energy between the two (or three or four) "bands" (frequency ranges), then on to the speakers. Passive crossovers are fixed at the frequency they split the signal, and you can expect a little power loss, but nothing too bad. Also, the crossover freq "slope" is fixed. Basically, a passive crossover is made specific for a certain speaker box, with the x-over freq and slope being "optimized" for the drivers and box design. I use optimized very freely. Often, the x-over/driver/enclosure design is far from optimized!
Active crossovers work a bit difference. These are line level devices that go between the mixer (or graphic eq that is after the mixer) and the power amps. They usually allow you to pick the x-over freq and to adjust the slope. They then have a output level for the bands, meaning, the bass, midrange, and treble (assuming it is a 3 way design) have seperate output level control. Without getting to deep into the whole thing, the seperate output levels allow you to control the overall sound a lot easier. Obvoiusly, an active crossover can be used with various driver/enclosure designs, and they tend to more efficiently use the available power than passive crossovers do.
Hope this helps a bit.
Ed
Passive crossovers are usually installed in the speaker box. A capasitor and a coil are used in tandem to split the energy between the two (or three or four) "bands" (frequency ranges), then on to the speakers. Passive crossovers are fixed at the frequency they split the signal, and you can expect a little power loss, but nothing too bad. Also, the crossover freq "slope" is fixed. Basically, a passive crossover is made specific for a certain speaker box, with the x-over freq and slope being "optimized" for the drivers and box design. I use optimized very freely. Often, the x-over/driver/enclosure design is far from optimized!
Active crossovers work a bit difference. These are line level devices that go between the mixer (or graphic eq that is after the mixer) and the power amps. They usually allow you to pick the x-over freq and to adjust the slope. They then have a output level for the bands, meaning, the bass, midrange, and treble (assuming it is a 3 way design) have seperate output level control. Without getting to deep into the whole thing, the seperate output levels allow you to control the overall sound a lot easier. Obvoiusly, an active crossover can be used with various driver/enclosure designs, and they tend to more efficiently use the available power than passive crossovers do.
Hope this helps a bit.
Ed
barefoot
barefootsound.com
Expanding a little on what Ed wrote:
In any well designed speaker system the crossover will be optimized to account for the particular response, phase, and impedance characteristics of the individual speaker drivers. The biggest practical difference between active and passive crossovers is this. Passive crossovers look directly into the driver loads and, therefore, are very dependent on the frequency dependent impedance characteristics of the drivers. Active crossovers are buffered from the drivers by the power amplifiers and, therefore, only care about the speakers' response and phase characteristics.
Editorial:
"Generic" active crossover units with adjustable x-over frequencies, slopes, levels, etc. are only useful for sound reinforcement systems.... where nobody really cares much about accuracy or sound quality anyway. Why? Because, in order get a good crossover alignment with the simple filter type these units provide, the high and low frequency speakers sections must have a flat response overlap of about 2 to 3 octaves. This refers to sharp 4-order filter slopes. Shallower slopes require even wider overlap.
Systems almost never have components with this sort of frequency overlap. So the sound engineer must resort to delay (phase) manipulation in order to level out the response. This, however, only works for a very particular listening axis and creates horrible nodes and antinodes (lobes) at other listening angles.
The "optimized" crossover alignments in well designed speaker systems almost never fall into the simple types (Butterworth, Bessel, L-R, etc....) found in these generic active crossover units. Even the fancy new digital "multiprocessor" units don't yet have the flexibility to create truly optimized crossover alignments.
Thomas
http://barefootsound.com
In any well designed speaker system the crossover will be optimized to account for the particular response, phase, and impedance characteristics of the individual speaker drivers. The biggest practical difference between active and passive crossovers is this. Passive crossovers look directly into the driver loads and, therefore, are very dependent on the frequency dependent impedance characteristics of the drivers. Active crossovers are buffered from the drivers by the power amplifiers and, therefore, only care about the speakers' response and phase characteristics.
Editorial:
"Generic" active crossover units with adjustable x-over frequencies, slopes, levels, etc. are only useful for sound reinforcement systems.... where nobody really cares much about accuracy or sound quality anyway. Why? Because, in order get a good crossover alignment with the simple filter type these units provide, the high and low frequency speakers sections must have a flat response overlap of about 2 to 3 octaves. This refers to sharp 4-order filter slopes. Shallower slopes require even wider overlap.
Systems almost never have components with this sort of frequency overlap. So the sound engineer must resort to delay (phase) manipulation in order to level out the response. This, however, only works for a very particular listening axis and creates horrible nodes and antinodes (lobes) at other listening angles.
The "optimized" crossover alignments in well designed speaker systems almost never fall into the simple types (Butterworth, Bessel, L-R, etc....) found in these generic active crossover units. Even the fancy new digital "multiprocessor" units don't yet have the flexibility to create truly optimized crossover alignments.
Thomas
http://barefootsound.com
I am far from an 'expert' in crossover talk, but have to know a bit just to deal with all the live sound I do.