BoxLab: Speaker Box Designer

Design speaker boxes and passive crossovers from your driver's Thiele-Small parameters — sealed, bass reflex, bandpass, passive radiator and horn. BoxLab runs the real acoustic math on your phone, offline, with no ads and no subscription. No simplified formulas: exact Small 1974 model for the passive radiator, true Webster 1D simulation for the horn, driver impedance with motional impedance, baffle diffraction, group delay and phase on every design. ✦ PRO-GRADE MATH • Passive radiator — Small (JAES 1974) pressure transfer function with double notch: ωp loaded on the driver cone excursion + ωr free-air on the SPL response • Horn — 1D Webster equation solved via cascaded ABCD matrices over 60+ segments, terminated by piston-in-baffle mouth radiation (Bessel J1 + Struve H1 series) • Exact horn profiles: exponential, Salmon hyperbolic, analytic tractrix, Le Cléac'h, conical (linear radius) • Alignment helper B4 / QB3 / C4 / SBB4 with suggested Mmp and target Vb ✦ ENCLOSURE DESIGN • Sealed box — Qtc, Fc, F3 with Butterworth / Chebyshev alignments • Bass reflex — 5 alignments (B4, QB3, C4, SBB4, EBS) + port velocity check • 4th-order bandpass with internal divider and port shown in 3D section • Passive radiator with Fp tuning and added-mass suggestion • Front / back-loaded horn with compression chamber and rear chamber ✦ PASSIVE CROSSOVER 2/3-WAY • Butterworth, Linkwitz-Riley, Bessel filters (1st–4th order) • Real driver impedance Z(f) with motional impedance Bl²/Z_mech • Zobel network + L-pad for tweeter attenuation • Manual override of every L/C component • Baffle diffraction — Vanderkooy edge model: baffle step, ripple and the arrival-time offset between drivers ✦ MULTI-DRIVER CONFIGURATIONS • Parallel, Series, Series-Parallel • Isobaric Series / Parallel — Vas halved, enclosure half the size • Push-Pull with HD2 harmonic cancellation (~12 dB) ✦ INTEGRATED 3D RENDERING • Oblique projection for sealed, ported, PR • Side section for bandpass (2 chambers + divider) and horn (chamber + actual flare from profile) • 6 ratio presets: Golden, EBU, Sepmeyer, Louden, Cube, Custom • Internal / external dimensions, panel area for material estimation ✦ MEASUREMENT & DISTORTION (PRO) • Real-time SPL meter A/C/Z + LAeq, 1/3-octave spectrum 16 Hz – 16 kHz • In-room measurement: pink noise / sweep + mic with overlay measured vs predicted • HD2 / HD3 / THD distortion vs frequency with push-pull toggle • Microphone offset calibration ✦ DATABASE & PROJECTS • Unlimited driver database (Pro) • Driver import via datasheet copy / paste — the parser extracts Fs, Qts, Vas, Bl, Re, Sd, Mms, Cms, Xmax, Pe • Save projects and Systems (woofer + midrange + tweeter + crossover + cabinet) • PDF export with vector charts, sharing and printing ✦ OFFLINE, ZERO TRACKING • 100% offline, no internet connection required • No accounts, no registration, no login • No data collected, no analytics, no ads • 9 languages: IT, EN, DE, FR, ES, JA, ZH (Simplified & Traditional), KO ✦ PRO ONE-TIME PURCHASE The free version includes sealed box, bass reflex, 2-way crossover, 3D dimensions, SPL meter, and up to 3 saved projects. Pro unlocks bandpass, passive radiator, horn, 3-way crossover, in-room measurement, distortion analysis, multi-module systems, PDF export, and unlimited projects. Pay once, no subscriptions, no renewals. Mathematically validated: 51 unit tests cover Thiele/Small, vented alignments, Small 1974 PR model, horn profiles and Webster simulation. For: DIY hobbyists, builders, audio engineers, acoustics students, sound engineers looking for a precision tool outside the studio.