Crossover Calculator
A crossover network splits an audio signal into frequency bands so each speaker driver handles only the range it was designed for. The woofer gets low frequencies through a low-pass filter, and the tweeter gets high frequencies through a high-pass filter. This calculator gives you the exact capacitor and inductor values for first-order (6 dB/octave) and second-order Butterworth (12 dB/octave) passive crossover designs.
The component values depend on three things: the crossover frequency, the speaker impedance, and the filter order.
First-order crossover (6 dB/octave):
- High-pass capacitor: C = 1 / (2pifc x Z)
- Low-pass inductor: L = Z / (2pifc)
- Uses just one component per driver
- Gentle slope means drivers overlap significantly near the crossover point
- Phase-coherent (no phase shift between drivers at crossover)
Second-order Butterworth (12 dB/octave):
- Steeper rolloff with two components per driver
- Uses sqrt(2) multiplier for flat amplitude response
- Introduces 180 degrees of phase shift (reverse tweeter polarity to compensate)
- Better separation between drivers reduces interference
Common crossover frequency choices:
- 80-120 Hz: Subwoofer to midrange
- 200-500 Hz: Woofer to midrange (3-way system)
- 2000-4000 Hz: Midrange to tweeter
Use non-polarized film capacitors (polypropylene preferred) and air-core or low-DCR inductors for best audio quality. Electrolytic capacitors work in budget builds but add distortion.