How to Make a Passive Crossover for a Car Stereo
A passive crossover filters out lowpass or highpass frequencies from reaching midrange, midbass and tweeter speakers. Applying one to your car stereo system may improve the clarity and power of your mobile sound output.
- Difficulty:
- Moderate
Instructions
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1
Understand that there are three orders of passive crossover: a capacitor or coil on a speaker; a coil and capacitor on a speaker; and either two coils and one capacitor or two capacitors and one coil on a speaker.
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2
Know that a lowpass filter (a coil) allows low frequencies to pass through. The speaker could receive 5,000 Hz and lower or 100 Hz and lower depending on the size, or value, of the coil being used.
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3
Know that the highpass (capacitor) filter allows only highpass frequencies through to the speaker.
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4
Know that a bandpass filter (capacitor and coil) allows only midrange frequencies to pass through to the speaker.
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5
Consider the ohms rating of the speaker you will be putting a passive crossover on. You need to match the proper value of the coil or capacitor to the speaker. If you are using a 4 ohm speaker, you need to be using a coil or capacitor that is also 4 ohms.
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6
Obtain charts that match the proper ohms rating and value of the coil or capacitor to the frequency you want to reach. These charts can be obtained from companies that offer passive crossover components, including Pacific Accessory Corporation, Stinger (also known as Aamp of America), Scosche, and others.
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7
Determine the crossover frequency you want. Crossover frequencies for woofers include 80 or 85 Hz, 100 Hz, 125 Hz or 150 Hz and down. Crossover frequencies for midbass speakers include 85, 100, 125, 150, 300, 400 or 500 Hz to 4,000, 5,000, 6,000, 8,000 or 10,000 Hz. Crossover frequencies for tweeters are commonly 4,000, 5,000, 6,000, 8,000 or 10,000 Hz.
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8
Using the chart, select and purchase the proper value capacitor and/or coil.
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9
For a first-order lowpass filter, connect the coil in series to the positive lead of the speaker.
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10
For a first-order highpass filter, connect the capacitor in series to the positive lead of the speaker.
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11
For a bandpass speaker, connect the capacitor and coil in series to the positive lead of the speaker.
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1
Tips & Warnings
Make sure that the passive crossover can handle the power fed to it by the amplifier.
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Comments
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good stuff
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inspirevv32
Oct 03, 2010
Wow, not a transistor, a CAPACITOR I meant! Sorry for that... -
inspirevv32
Oct 03, 2010
Awesome article, tried te tips and they worked exact! I got a big transistor from an old computer power supply and it worked just as planned cut out the low end bass but stll left the mid and treble. Hope it takes the power my receiver puts out but if it came from a computer power supply, I would think it could. (Bigger the transistor = more treble & mid) (Smaller transistor = just treble) Havent really tried the coils of wire yet for low pass. But im guessing bigger the coil the lower the bass will be. Smaller coil leads to more mid range being with the bass.
