Speaker Crossover Calculator

Speaker Crossover Calculator estimates passive two-way crossover component values for a woofer low-pass branch and tweeter high-pass branch using nominal driver impedances.

Speaker Crossover Calculator formulas

Inductance is calculated in henries, capacitance in farads, frequency in hertz and impedance in ohms. For second-order networks, the inductor and capacitor exchange series and shunt positions between the low-pass and high-pass branches.

Worked example

At 3,000 Hz with 8 Ω woofer and tweeter impedances, a second-order Butterworth starting network uses approximately 0.600 mH and 4.688 µF in the woofer branch. The tweeter branch uses approximately 4.688 µF and 0.600 mH. Nearby standard values may be selected, but measurements determine whether those substitutions improve the acoustic response.

Designing a practical speaker crossover

A passive crossover separates an amplifier signal into frequency ranges for different drivers. The low-pass branch reduces high-frequency energy reaching the woofer, while the high-pass branch protects the tweeter from excessive low-frequency energy. Electrical slope describes the ideal network, but the final acoustic slope also includes each driver’s natural response.

Nominal impedance is an approximation

A driver labeled 8 Ω does not remain at 8 Ω across frequency. Its impedance curve contains a resonance peak and usually rises at high frequencies because of voice-coil inductance. The Speaker Crossover Calculator assumes a resistive value at the crossover point. For better accuracy, use measured impedance data or an impedance-compensation network designed for the actual driver.

Butterworth and Linkwitz–Riley alignments

A first-order Butterworth filter uses one reactive component per driver and has a gentle 6 dB-per-octave electrical slope. A second-order Butterworth network is steeper and ideally has a Q of about 0.707. A second-order Linkwitz–Riley response uses a Q of 0.5 and is often selected when designers want the acoustic outputs to sum predictably after accounting for polarity and driver behavior.

Polarity and acoustic phase

Second-order electrical branches have a relative phase relationship that commonly leads designers to begin testing with one driver reversed. This is guidance, not a universal wiring rule. Driver acoustic centers, natural roll-off, enclosure geometry and listening axis affect the measured phase. Verify the summed response around the crossover frequency.

Component quality and ratings

Use capacitors with appropriate voltage and loss characteristics and inductors with suitable wire gauge, current capability and low DC resistance. Inductor resistance changes the woofer level and filter Q. Capacitor tolerance changes crossover frequency. High-power systems require components that tolerate expected RMS and peak conditions without overheating.

Measurement is essential

The Speaker Crossover Calculator provides textbook electrical values, not a finished loudspeaker design. Measure frequency response, impedance and distortion in the intended enclosure. Adjust for driver sensitivity using attenuation where needed and check tweeter power handling below the crossover point. Simulation based on manufacturer FRD and ZMA data is much more reliable than nominal impedance alone.

Review established passive-filter theory and measurement practice in the Linkwitz filter design reference. Always confirm manufacturer specifications and protect the amplifier from unsafe impedance.

Related electronics calculators

Frequently asked questions