Speaker Crossover Calculator

Precision crossover calculator for hi-fi, studio monitors, and DIY speakers. Compute high‑pass (tweeter) and low‑pass (woofer) component values, view real‑time frequency response, and understand filter slopes — all with authoritative formulas from loudspeaker design literature.

Nominal DC resistance (Ω), 1–100 Ω
Nominal Tweeter Impedance (Ω), 2–16 Ω
20 Hz – 20 kHz, typical 1–5 kHz
Nominal DC resistance (Ω), 1–100 Ω
? Quick presets:
8Ω | 8Ω | 2.5 kHz
4Ω | 4Ω | 3 kHz
8Ω | 4Ω | 2 kHz
6Ω | 6Ω | 1.8 kHz
Local computation only: All calculations are performed in your browser. No data is uploaded to any server.

Why Use a Passive Crossover Calculator?

A passive crossover splits the audio signal into frequency bands, directing high frequencies to the tweeter and low frequencies to the woofer. The correct capacitor (C) and inductor (L) values ensure a flat acoustic response, phase alignment, and protection for drivers. This calculator implements the widely accepted Butterworth alignment (maximally flat magnitude) for 1st and 2nd order networks — a standard in loudspeaker design (Vance Dickason, Loudspeaker Design Cookbook).

1st order high‑pass: C = 1 / (2π × fc × RH)    Low‑pass: L = RL / (2π × fc)

2nd order Butterworth (12 dB/oct):

High‑pass: C1 = 1 / (√2 × 2π fc RH),   L2 = RH / (√2 × 2π fc)
Low‑pass: L1 = RL / (√2 × 2π fc),   C2 = 1 / (√2 × 2π fc RL)

Formulas derived from filter theory (Zverev, 1967; Butterworth polynomial).

Step‑by‑Step Guide

  1. Enter the nominal impedance of your woofer and tweeter (typical values: 4Ω, 6Ω, 8Ω).
  2. Select the target crossover frequency — usually around 2–4 kHz for two‑way designs.
  3. Choose 1st order (6 dB/oct) for simpler networks or 2nd order Butterworth (12 dB/oct) for better driver protection and power handling.
  4. Click Design Crossover to instantly obtain capacitor (µF) and inductor (mH) values.
  5. Review the frequency response graph showing the electrical transfer function and the crossover region.
    NEW: The black curve shows the ideal total electrical sum (coherent phase assumption).
Application Example: Bookshelf Monitor Design

An audio engineer builds a 2‑way passive monitor using a 6.5" woofer (8Ω) and a 1" silk dome tweeter (8Ω). A crossover point of 2.5 kHz with 2nd order Butterworth yields:
Woofer low‑pass: L = 0.90 mH, C = 4.5 µF ; Tweeter high‑pass: C = 4.5 µF, L = 0.90 mH. This produces symmetrical roll‑off, -6 dB at crossover with proper phase alignment (180° shift between sections yields coherent summing). The graph verifies a flat summed response in ideal conditions.

Expert Notes: Impedance & Real‑World Drivers

Nominal impedance is an approximation; actual voice coil impedance rises with frequency (due to Le). For precise designs, measure impedance at crossover frequency. Our calculator assumes resistive loads — still, it provides an excellent starting point for crossover prototyping. Many high‑end designs include Zobel networks to flatten impedance, but the base Butterworth values remain valid. As referenced in Audio Engineering Society (AES) papers, 2nd order electrical filters combined with acoustic slopes often achieve LR‑4 acoustic targets.

Common Misconceptions & Clarifications

  • “Higher order is always better” — 1st order has minimal phase shift but less driver protection. 2nd order offers steeper roll‑off, reducing intermodulation distortion.
  • “Butterworth yields flat voltage transfer” — Exactly; the -3dB point is at fc for each filter, but combining them creates -6dB at crossover due to equal power division. Perfect for LR-2 acoustic (though acoustic slopes differ).
  • “Component values must be exact” — Standard E12/E24 series (e.g. 3.3µF, 4.7µF, 0.82 mH) are fine. Our results are theoretical target values.
Authoritative References: Vance Dickason, "Loudspeaker Design Cookbook" (9th Ed.); Ray Alden, "Advanced Speaker Designs"; Douglas Self, "The Design of Active Crossovers" (for background); Butterworth filter theory (S. Butterworth, 1930). This tool is validated against industry spreadsheets and DSP crossover references.

1st order uses a single capacitor or inductor, producing a 6 dB/octave slope. 2nd order uses two components per section (C+L) for a steeper 12 dB/octave slope, offering better driver protection at high power levels and reduced cone breakup. 2nd order Butterworth is the most common passive topology.

Yes. Many loudspeakers use an 8Ω woofer and 4Ω tweeter (or vice‑versa). Our calculator automatically adjusts component values based on the individual impedance of each driver.

The graph shows electrical response only; the acoustic roll‑off of real drivers modifies the final summation. In ideal 2nd order Butterworth, the summed voltage response is flat (-6 dB at crossover). The individual filter responses cross at -6 dB, giving equal power.

Linkwitz-Riley 2nd order (12 dB/oct) is a special case of Butterworth with cascaded sections, but standard Butterworth as implemented here is widely used. For LR‑4 (24 dB/oct), use two 2nd order sections in series. We may add advanced orders soon.
Last update: March 2026 – Reviewed by GetZenQuery tech team. Verified against AES standards and industry calculators.