Speaker Crossover Calculator (Component Values)

Bracket it from both drivers' limits: the tweeter sets the floor — cross at least an octave above its resonance (Fs 700 Hz → cross no lower than 1.4 kHz, higher with shallow slopes) or excursion and distortion soar; the woofer sets the ceiling — beaming begins where wavelength equals cone diameter (a 6.5-inch mid-woofer beams above ~2 kHz) and breakup follows. Typical sweet spots: 2–3 kHz for dome-tweeter two-ways, 80 Hz for sub/satellite splits (the THX convention — below where localization begins). The 2.5 kHz default is the industry's center of gravity for a reason.

Slope against phase and parts: 1st order (6 dB/oct) is one component per driver and the only type preserving a perfect transient waveform — but drivers must behave two octaves past the crossover, which real tweeters resent (distortion, power handling). 2nd order LR (12 dB/oct) protects drivers far better, sums flat with the tweeter inverted, two parts per driver. 4th order LR (the pro/studio standard) isolates drivers almost completely at the cost of four parts per leg and more group delay. Higher order = better driver protection, worse transient purity, more money in copper and film.

Three liars: impedance (the formula assumed 8 Ω; the driver's curve swings 6–40 Ω — a Zobel network flattens the woofer's rise, or the crossover point slides up and the slope warps), sensitivity mismatch (tweeters typically run 2–4 dB hotter than woofers and need an L-pad), and acoustic centers (the tweeter's voice coil sits ahead of the woofer's, so their outputs arrive misaligned at the crossover — the reason commercial designs measure, tilt baffles, or fix it in DSP). The values from this page are the correct STARTING point; speakers are finished with a measurement mic.

Passive remains right for finished consumer speakers (one amp, no electronics per box) — but actives have quietly won everywhere else: studio monitors, PA, car audio DSP and DIY-with-plate-amps all filter BEFORE amplification, where a crossover is software (any slope, any delay, driver time-alignment for free) and each driver gets a dedicated amp channel. The economics crossed over too: a 2×100 W DSP plate amp costs less than the film caps and air-core inductors of a serious LR4 passive network. Learn the passive math — this page — and then check whether your project shouldn't simply skip it.