W-Body Car Audio
| W-Body Car Audio |
| Car Audio Basics |
| Crossovers |
| Active Crossovers |
| Passive Crossovers |
Crossover Basics
What Does a Crossover Do?
To put it simply, a crossover filters out unwanted frequencies. This is done because no one speaker can produce the entire musical spectrum by itself. Your tweeters can't play deep bass, and your subwoofers reproduce vocals with the clarity of those X-Ray glasses you find in junk stores.
The crossover comes in two flavors: Active and Passive.
What does "Order" or "Slope" mean?
A crossover filters by certain degrees. Just like the Dolby Noise Reduction on your cassette deck cannot remove all the noise from your tape collection, a crossover cannot remove all of the unwanted frequency range. You can reduce the output to inaudible levels, though.
A first order crossover will reduce the unwanted frequencies by 6db/octave. The crossover point is usually referenced by the point at -3dB. This means that the signal has already been reduced by -3dB.
Remember that an octave represents a doubling of frequency. If a -3db point is at 100hz, and the slope is 6dB/octave, that means the signal will be attenuated -9dB at 200hz, and -15dB at 400hz, etc. If the slope were 12dB/octave, 200hz would be attenuated -15dB while 400hz would be attenuated -27dB, etc.
The chart below illustrates this, as well as 3rd and 4th order slopes:
