How to Select the Crossover Point to Use on a Subwoofer

To select the crossover point to use on your subwoofer, you'll have to choose between a passive crossover and an active one. The crossover is used to determine which frequencies are delivered to which speakers, subwoofers and amplifiers, as well as the levels at which they're delivered. It's relatively easy to choose a passive crossover point, but things get a little more complicated if you want to customize your audio experience by implementing an active one.

Difficulty: Moderate

Instructions

Pick a Passive Crossover Point

1. Choose a passive crossover if you're looking for a cheap, simple solution to your sound troubles. A passive crossover is a coil or capacitor that attaches right onto your speaker lead or subwoofer, filtering audio at prespecified ranges (which are specified on the packaging when you buy one).

2. Keep in mind that your subwoofer is used to re-create the bass frequencies in music. Thus, to select a crossover point that's going to make a tangible difference in your sound quality, you'll have to choose one that's in the middle range of the low-frequency end of the spectrum. Bass is usually defined as 300 Hertz or lower, so a passive crossover should be in the 200-hertz range to be effective.

3. Add a crossover point to your speakers rather than your subwoofer, if you'd rather simply filter out high frequencies from low frequencies and send each to a dedicated speaker. Due to the relatively limited range of bass frequencies, altering your speakers instead of your subwoofer can be a useful alternative.

Choose Active Crossover Points

4. Make use of a three-way network of active crossover points to maximize your car's audio system capabilities. Active points actually process the signal before it's sent along to your amplifier, and using low-pass, mid-pass and high-pass filters can help you customize your music-listening experience. Ideal levels are primarily identified through trial and error.

5. Use 100 hertz as a ballpark figure if you want your low-pass filter to create a deep, echoing boom. This is the preference of many rap and hip-hop fans. You can go as low as 80 hertz if you want to tighten the sound but keep its "boom." However, the lower your low-pass filter goes, the more difficult it becomes to distinguish subtleties in the sound.

6. Select a high-pass crossover point in the range of 3,000 hertz. This will ensure that low- and mid-range sounds are being separated from the highest-pitched sounds, allowing you to dedicate a speaker to playing back only the highest frequencies. The high-pass crossover point is more applicable to your amplifier and speakers than your subwoofer, because subwoofers are dedicated to low-frequency bass tones.

7. Use what's known as a band-pass active crossover point to moderate the frequencies that are higher than the low-pass threshold, but lower than the high-pass threshold. This will ensure their even distribution across all the speakers in your system. If your low-pass filter is set to 100 hertz and your high-pass filter is set to 3,000 hertz, your band-pass filter will be a "100-3,000."

8. Try a variety of different low-pass, high-pass and band-pass crossover points while you are playing the kind of music you expect you'll be listening to most often. Trial and error is the best way to optimize your listening experience, since everyone has their own individual preferences.

Tips & Warnings

• If you run a stereo system without a crossover point, your sound quality will suffer noticeably. The crossover is used to filter certain frequencies out, sending high frequencies to a dedicated speaker and low frequencies to another. When these filters aren't present, all speakers in the system reproduce similar frequencies, sounding more like a sonic jumble than a symphony.