A speaker crossover separates the full-range signal from the amplifier and divides it into component sections that the woofer and tweeter reproduce. Since each speaker driver can only effectively reproduce certain segments of the signal without audible stress or failure, a crossover is essential. After the total impedance of the woofer and tweeter are properly ascertained, wiring the individual drivers using a preassembled two-way crossover is a straightforward process.
If you use a woofer and tweeter purchased separately or are unsure of the impedance of each, use a multimeter to determine the load. Set the dial on your multimeter to the 200-ohm setting. Place the positive and negative probes on the speaker terminals and note the readings. Understand that the actual readings may be a little lower than the listed impedance. For example, an 8-ohm speaker might read as low as 6 ohms. Add the two readings together to determine the final impedance when the drivers are wired together. Note the impedance specifications on your amplifier. Most will state a minimum and maximum impedance. This means the amplifier will work as intended between these figures.
Which Is Which?
Looking at the crossover board filled with capacitors and resistors, you may initially be a little confused. Closer examination reveals small printing on the board, indicating the wiring outputs for the woofer and tweeter in a two-way speaker system. For each, you should see a black and red flying lead, one intended to wire to the tweeter and the other to the woofer. These are usually marked as "T+" or "W+" for the tweeter and woofer's positive terminals, respectively. There will also be a separate pair of positive and negative wires for connection to the speaker's terminal cup, mounted to the outside of the speaker cabinet. These will be labeled "In," "+" and "-".
The ends of the flying leads are probably prestripped. Pull the loose insulation from the end of each wire and crimp on a female spade connector corresponding to the size of the tabs on the terminal cup, woofer and tweeter. Using these connectors instead of soldering makes driver replacement fast and easy, while providing a solid connection. The highest-end commercial speaker manufacturers use this exact connection method.
Putting it All Together
Hot-glue a piece of felt or foam rubber on the bottom of the speaker cabinet where the crossover will sit. This isolates the crossover from signal-damaging vibration. Screw the crossover to the inside bottom of the speaker cabinet, using caution to not overtighten the screws and crack the crossover board. Make each connection to the terminal cup, woofer and tweeter as indicated on the crossover board's markings. Screw the drivers and cup to the speaker cabinet to complete the project.
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