Audio Crossover Calculator
Design 2-Way Passive Speaker Crossovers.
What is an Audio Crossover?
An Audio Crossover splits the full-range audio signal into separate frequency bands. It sends high frequencies to the Tweeter (which can be destroyed by bass) and low frequencies to the Woofer.
This calculator designs Passive Crossovers, which sit between the amplifier and the speakers using large capacitors and inductors.
Crossover Types & Formulas
1st Order (6 dB/octave)
The simplest crossover. Just one component per driver. It has a gentle slope.
Low Pass (Inductor): L = Z / (2π × f)
High Pass (Capacitor): C = 1 / (2π × Z × f)
2nd Order (12 dB/octave)
Most common. Offers better protection for tweeters. We use the Linkwitz-Riley alignment (Q=0.5) for flat summing.
Low Pass: L = Z / (π × f), C = 1 / (4π × Z × f)
High Pass: C = 1 / (4π × Z × f), L = Z / (π × f)
Practical Applications
- Hi-Fi Speakers: Almost all bookshelf speakers use a passive 2-way crossover inside the box.
- Car Audio: Component speaker systems come with external crossover boxes to separate the door woofer from the dash tweeter.
- PA Systems: Protecting horn tweeters from blowing out during high-volume events.
FAQ
What capacitors should I use?
Non-Polarized capacitors are required. For audio quality, Polypropylene film (MKP) capacitors are best. Cheap datasheets use "Bi-polar Electrolytic" caps, which degrade over time.
Should I reverse the tweeter polarity?
For 2nd Order (12dB) crossovers, yes! A 2nd order filter shifts phase by 180°. Wiring the tweeter "backwards" (+ to -) brings it back in phase with the woofer relative to the listener.
Does impedance matter?
Yes, critically. A crossover designed for 8Ω speakers will have the wrong frequency if connected to 4Ω speakers. The crossover frequency will double or halve depending on the circuit.