A crossover is a piece of audio signal processing equipment that divides a single stereo audio signal into two, three, or even four frequency ranges. A crossover, at a bare minimum, ensures that the high-frequency signal (i.e., the treble) is directed primarily to your tweeter speakers, while the low-frequency signal (i.e., the bass) is directed to your woofers or subwoofers. The use of a crossover in your speaker setup can greatly improve sound quality by isolating frequency groups to specific speakers or speaker drivers, resulting in greater clarity. There are two types of crossovers: passive crossovers, which are the easiest to install, and active crossovers, which are a little trickier, more expensive, and necessitate the use of multiple amplifiers, but provide you with more control over your sound. These instructions will walk you through the process of connecting either type of crossover for your home stereo or a PA system.
Method 1 Wiring a Passive Crossover
1. Unplug your speakers. If there are speakers currently wired up to your stereo system, fully disconnect them.
2. Connect the output of the amplifier to the crossover. Connect the crossover to your amplifier using speaker wire or RCA cables (depending on your stereo system and crossover unit).
Before the speakers, the crossover should be the last piece of equipment in the chain. Depending on your setup, this could mean that your crossover is wired directly between your amplifier and your speakers, or that it is wired after a compressor or equaliser.
Depending on your crossover and stereo setup, you will most likely require separate crossover units for your stereo system’s left and right channels.
Connect the amplifier’s output to the crossover inputs by connecting speaker wires to the positive and negative terminals of your amplifier and the crossover’s corresponding inputs. Use a red wire for the positive terminal and a black wire for the negative terminal. Tighten the terminals after sliding the exposed wire ends into place.
Depending on the amplifier and crossover unit, this can be accomplished by either flipping small switches above the terminals or tightening screws with a screwdriver or allen wrench.
If there isn’t enough exposed wire at the ends of your speaker wires, you may need to use wire strippers to remove up to half an inch of insulation.
3. Connect the output of the crossover to the speakers. Using speaker wire, connect your speakers to the crossover, just as you did in the previous step.
Separate outputs for your woofers (bass speakers) and tweeters should be provided by your crossover (treble speakers). Make certain that the correct speaker is connected to the correct output.
Many crossover models will have the woofer positive and negative outputs labelled W+ and W-, and the tweeter positive and negative outputs labelled T+ and T-.
4. Try it out. Play some music through your system after you’ve wired the left and right channels. Both channels should produce a clear sound.
If your crossover is adjustable and you’re not satisfied with the sound, try adjusting the frequency knobs or consulting the instructions for recommended settings.
Method 2 Wiring an Active Crossover
1. Unplug your speakers. If you have speakers already connected to your stereo, fully disconnect them.
2. Install the crossover. Active crossover units are larger than passive crossover units and must be installed in a stable location, preferably near your amplifiers.
Do not directly mount your crossover to a metal rack, as this can cause buzzing and other sound issues.
3. Connect your receiver to the crossover. Wire your crossover into the receiver or preamp using the appropriate cables, with the wires coming out of the receiver going into the crossover’s “in” terminals.
RCA cables will most likely be used to connect your receiver and stereo system, but some crossovers are set up to use speaker wire instead (as detailed in Method 1) if your receiver does not have RCA outputs.
Crossovers for PA systems may use quarter-inch cables, similar to those used to plug in an electric guitar, or XLR cables, similar to those used to plug in a microphone.
4. Connect your amplifiers to the crossover. Connect the appropriate outputs to the appropriate amplifiers using the appropriate cables (usually RCA or speaker wire for a home stereo system).
If you don’t have a subwoofer, send the high-frequency signal to your tweeter amp and the low-frequency signal to your woofer amp. In this case, ensure that your crossover is set to two-way operation. This should be controlled by a switch. Check your instruction manual if you can’t find it.
Connect the left output of each frequency range to the coinciding amplifier’s left input and the right output of each frequency range to the coinciding amplifier’s right input.
5. If you have a subwoofer, connect it. There are several methods for connecting a subwoofer to your system. Whichever option you choose, you’ll need to configure your crossover so that the mid-frequency signal is sent to the woofers but not the low-frequency signal.
One option is to run additional cables from your crossover to your subwoofer (or subwoofer amplifier, if your subwoofer lacks its own power). In this case, you’ll set the crossover to three-way mode if you’re connecting to separate woofers and tweeters, or two-way mode if you’re running a full-range signal through the main speakers and only sending bass to the subwoofer.
Another option is to run cables directly from your receiver’s subwoofer-out (sub out) terminals. If you have a newer receiver, it may have its own crossover settings for a subwoofer, eliminating the need for an external crossover.
If your receiver lacks subwoofer controls, your subwoofer most likely has a built-in crossover. These typically do not produce the best sound, but they are simple and convenient, and they allow you to avoid using an external crossover unit.
If you’re connecting your subwoofer to an external crossover, remove the built-in crossover from the circuit by turning it to its maximum rotation. Having multiple crossovers active at the same time can cause the bass input to be uneven or erratic.
Subwoofers should not be connected with speaker wire. It cannot handle bass signals as well as more robust cables.
6. Connect the power to the crossover and turn it on. Power is required for active crossovers to function. Home stereo and PA system crossovers typically plug into an outlet, whereas car stereo units, such as the one shown in the video below, must be connected to the vehicle’s power supply via the fuse box, or the amplifier may have a terminal for sending power to a crossover.
7. Fine-tune your system. At this point, you should fine-tune your system to get the sound you want. The owner’s manual for your crossover should have some suggestions, but you can also follow the guidelines below. At the start of this process, make sure the input gain on your crossover is all the way down (if it has an input gain knob), set your amplifier gains low, and turn off or set the levels all flat if you have an equaliser.
Turn on the system and listen to some familiar music. This way, you’ll have a good idea of what the music is supposed to sound like.
Turn up the input gain on the crossover gradually until sound comes out of all of your speakers.
Adjust the level of each crossover output until the frequencies are playing at the same volume. Because each crossover model is unique, you should consult your owner’s manual for specific instructions, as well as the manufacturer’s recommended settings.
Turn up the gains on your amplifiers one at a time until the music begins to distort slightly, then roll them back to just below the distortion threshold. Re-adjust the crossover frequencies as needed to restore frequency balance.
Turn on your equaliser and start adjusting the sound to your personal preferences. Make any changes you want to your receiver, such as the tone, etc. Adjust the crossover frequencies once more until the sound is balanced.
Continue fine-tuning your receiver, equaliser, and crossover settings until you achieve a pleasing sound mix.
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