What a 2-Way Crossover Does
A 2-way crossover splits audio into two bands so each speaker driver plays what it handles best: the woofer plays low/mid frequencies and the tweeter plays high frequencies. This improves clarity, reduces distortion, and protects your tweeter from low-frequency energy.
In a passive speaker, this split is created with inductors and capacitors. The exact component values depend on your chosen crossover frequency and the impedance of each driver. This calculator gives you a fast starting point for common textbook designs.
How This Calculator Works
Enter your target crossover frequency plus woofer and tweeter nominal impedance (for example, 8 Ω and 8 Ω). Then select filter type:
- 1st-order (6 dB/oct): one component per driver branch. Simpler and lower parts count.
- 2nd-order Butterworth (12 dB/oct): two components per branch, steeper roll-off and better separation.
Results are displayed as practical values in mH and µF along with approximate nearest E12 part values for easier component shopping.
Core Equations Used
1st-order network
Lwoofer = Zw / (2πfc)Ctweeter = 1 / (2πfcZt)
2nd-order Butterworth network
L = (√2 × Z) / (2πfc)C = √2 / (2πfcZ)
For 2nd-order designs, each branch (low-pass and high-pass) uses one series and one shunt component. In practice, these equations assume ideal resistive loads and are best treated as a baseline for further tuning.
Practical Build Tips
- Use air-core inductors for low distortion where possible.
- Prefer film capacitors in the tweeter path.
- Measure actual driver impedance curves if you want precision.
- Keep inductor coils physically separated and rotated to reduce magnetic coupling.
- Expect final voicing to require listening tests and measurements (REW, DATS, etc.).
Why Nominal Impedance Is Only a Starting Point
Real drivers are not flat resistors. Impedance changes with frequency, enclosure loading, and resonance. So a “2.5 kHz crossover” from textbook math may acoustically land somewhere else. That is normal. Designers often add compensation networks (like Zobel impedance correction, L-pad attenuation, notch filters, or baffle-step compensation) to get the final response right.
FAQ
Can I use this for car audio or home speakers?
Yes. The math is generic for passive 2-way crossovers.
Should I pick 1st-order or 2nd-order?
If you want simplicity and low component count, start with 1st-order. If you need better driver protection and cleaner band separation, choose 2nd-order.
Do I still need measurements?
Absolutely—if your goal is high fidelity. The calculator gives electrical target values, not final acoustic perfection.