Audio Crossover Calculator — Frequency, Slopes & Component Values
Crossover settings
At crossover if known; otherwise nominal.
At crossover if known; otherwise nominal.
Your settings stay in this browser. No frequencies or driver details are uploaded or stored.
Passive 2-way network
Woofer low-pass
Tweeter high-pass
Important: These are textbook electrical starting values for resistive 8 Ω loads. Real loudspeakers are reactive, so verify the design with impedance and frequency-response measurements before building or using it at power.
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How to use this passive crossover calculator
- Choose a safe crossover frequency. Check both driver datasheets and measured responses. Keep the tweeter comfortably above its recommended minimum crossover frequency and away from high-distortion regions.
- Select the electrical slope. Higher orders attenuate out-of-band signals faster but need more parts and become more sensitive to real impedance and component tolerances.
- Use impedance at crossover when possible. A nominal 8 Ω driver may be far from 8 Ω at the selected frequency. Manufacturer impedance curves are better than the badge rating; an actual measurement is better still.
- Read parts in signal order. “Series” parts go in the signal path. “Shunt” parts connect from the indicated node across the driver branch. The displayed sequence describes the ideal ladder order.
- Model, build, and measure safely. Refine the network in loudspeaker-design software using measured driver impedance and response data. Disconnect the amplifier before wiring, and use components rated for the expected voltage, current, and heat.
The nearest E12 or E24 value is convenient for sourcing, but it is not automatically the best final part. Combining parallel capacitors or series inductors can approach an exact value; the components’ tolerance and the inductor’s DC resistance still matter.
Which crossover slope and alignment should you choose?
| Alignment | Electrical behavior | Typical trade-off | Starting polarity |
|---|---|---|---|
| 1st-order Butterworth | 6 dB/oct; each branch −3 dB at crossover | Fewest parts and gentle phase rotation, but drivers must overlap broadly and tolerate more out-of-band energy. | Same polarity |
| 2nd-order Butterworth | 12 dB/oct; each branch −3 dB at crossover | Simple and steeper, but the ideal in-phase voltage sum peaks after correcting the 180° branch relationship. | Reverse one driver |
| 2nd-order Linkwitz–Riley | 12 dB/oct; each branch −6 dB at crossover | Ideal flat on-axis sum after polarity reversal, with only two reactive parts per branch. | Reverse one driver |
| 3rd-order Butterworth | 18 dB/oct; each branch −3 dB at crossover | Faster attenuation and ideal flat voltage sum, but more components and greater sensitivity to load error. | Same polarity |
“Starting polarity” describes the ideal electrical network only. Driver diaphragm offset, natural roll-off, polarity conventions, and acoustic phase can change the correct measured connection.
Crossover formulas and assumptions
Let f be crossover frequency in hertz, R the branch load in ohms, and ω = 2πf. Inductance is calculated in henries and capacitance in farads. The general scaling is:
L = kL × R / (2πf)C = kC / (2πfR)
The topology-specific normalized coefficients are applied in circuit order:
- 1st-order Butterworth: low-pass L1 = 1; high-pass C1 = 1.
- 2nd-order Butterworth: low-pass L1 = √2 and C2 = 1/√2; high-pass C1 = 1/√2 and L2 = √2.
- 2nd-order Linkwitz–Riley: low-pass L1 = 2 and C2 = 1/2; high-pass C1 = 1/2 and L2 = 2.
- 3rd-order Butterworth: low-pass L1 = 3/2, C2 = 4/3, L3 = 1/2; high-pass C1 = 2/3, L2 = 3/4, C3 = 2.
These are constant-resistance, zero-source-impedance ladder equations. They calculate the electrical filter response, not the finished acoustic crossover. A real driver’s impedance curve, voice-coil inductance, sensitivity, enclosure, baffle diffraction, physical offset, and natural response all modify the result. For that reason, this page is a starting-value calculator rather than a substitute for loudspeaker simulation and measurement.
Electrical and design limits
Passive crossover parts can carry hazardous amplifier voltages and significant current. Turn off and disconnect equipment before changing wiring. Confirm amplifier load compatibility, driver power limits, capacitor voltage and type, inductor current capacity and DC resistance, and resistor heat ratings where additional compensation is used. If you cannot measure the loudspeaker or assess component ratings, consult an experienced loudspeaker designer or technician.
Audio crossover calculator FAQ
Which impedance should I enter?
Use the driver’s impedance magnitude near the crossover frequency when measured data is available. Nominal impedance is acceptable only for a first estimate because the actual value changes with frequency.
What is the difference between Butterworth and Linkwitz–Riley?
A Butterworth branch is 3 dB down at its cutoff. The 2nd-order Linkwitz–Riley option is 6 dB down at crossover, allowing its two ideal electrical branches to sum to unity after one branch is polarity-inverted.
Why does a 12 dB/octave network suggest reversing one driver?
The ideal second-order low-pass and high-pass branches are 180° apart at crossover. Reversing either driver corrects that electrical relationship. Measurements determine whether the real system follows the ideal case.
Are nearest E12 and E24 values exact equivalents?
No. They are the closest values in a preferred-number series. The CSV preserves both the exact result and the preferred alternative so you can compare them.
Does this include voice-coil inductance, Zobel compensation, or an L-pad?
No. The model treats each driver as a fixed resistance. It does not calculate impedance compensation, sensitivity padding, notch filters, baffle-step compensation, or response equalization.
Can I use the result for a car or home loudspeaker?
The ideal equations are not installation-specific, but real impedance, temperature, available space, amplifier loading, and component ratings matter. Model and measure the installed system.
Are my settings uploaded?
No. Calculations, copying, and CSV generation happen locally in your browser.
Technical references
- Rane — Linkwitz–Riley Crossovers: A Primer, for crossover order, slope, phase, and summing behavior.
- Linkwitz Lab — Crossovers, for LR2/LR4 transfer relationships and driver polarity.
- Analog Devices — Basic Linear Design, Chapter 8: Analog Filters, for normalized passive filter implementation and frequency/impedance scaling.