LR24 · Linkwitz-Riley 24 dB/oct
Enter your driver's resonant frequency and cone diameter to instantly calculate safe Linkwitz-Riley LR24 high-pass and low-pass crossover points with an interactive response curve.
165.1 mm effective cone diameter
Safety multiplier: 1.3× Fs
HPF Cutoff (LR24)
—
1.3× Fs applied
Beaming / LPF Limit
661 Hz
c / (π × ø)
LR24 Response Curve
LR24 standard: Both HPF and LPF are set 6 dB down at their crossover frequencies and sum to 0 dB in the passband with 360° total phase alignment.
The Linkwitz-Riley LR24 alignment — two cascaded 2nd-order Butterworth filters — is the preferred crossover topology for active DSP systems for one fundamental reason: it produces a perfectly flat summed magnitude response at every frequency. Each filter presents −6 dB at the crossover frequency, and because a 4th-order LR pair accumulates 360° of total phase shift between the high-pass and low-pass outputs, both drivers are in polarity at the crossover point. Add them together and you get 0 dB — no peak, no dip, no colouration. Butterworth crossovers, by contrast, produce a +3 dB peak at the crossover point when drivers are summed acoustically, and Bessel alignments require careful spacing compensation. LR24 avoids both artefacts, making it the go-to choice for high-end DSP active builds.
Acoustic beaming occurs when the wavelength of sound becomes shorter than the radiating surface. A large cone acts as a piston; at low frequencies its output disperses omnidirectionally, but as frequency rises the radiation narrows into a forward-firing beam. The onset frequency is approximately f = c / (π × d), where c is the speed of sound (343 m/s) and d is the effective cone diameter in metres. For a 165 mm cone driver this falls near 660 Hz. Cross your midbass above this point and off-axis listeners hear a frequency response hole — the driver's high-frequency output simply misses them. Keeping the LPF at or below the beaming frequency preserves wide dispersion across the listening plane and is essential for a realistic soundstage. Smaller drivers beam at higher frequencies, which is why tweeters — with dome diameters of 19–30 mm — can operate well past 20 kHz without audible beaming artefacts.
Every driver has a resonant frequency (Fs) below which its suspension stiffness drops sharply and voice coil excursion rises rapidly for a given input voltage. Operating a driver below Fs at significant power levels risks bottoming the voice coil, tearing the spider, or melting the tinsel leads. Setting a high-pass filter above Fs — at a safe multiple — prevents the DSP or amplifier from driving the cone beyond its mechanical limits. The required safety margin depends on driver size and application: a robust subwoofer handling 20 Hz signals only needs a 1.2–1.5× multiplier; a 1" dome tweeter with an Fs of 800 Hz should be protected at 2–2.5× its Fs to keep the voice coil excursion within its small Xmax rating and ensure thermal survival at high SPL. High-power builds require wider margins because peak programme material can deliver 6–10 dB above the average power level, turning occasional transients into potential driver failures.
FAQ
Everything you need to set up LR24 active crossovers in your DSP with confidence.