Enclosure Designer

Enclosure Designer models sealed and vented loudspeaker enclosures. Work in the Design tab: choose a driver, set the box and port, and the plots on the right update live. The top tabs let you Compare designs, view off-axis behaviour (Baffle), manage the Drivers library, or read this Help. The left inputs and right graphs scroll independently.

Designs persist in this browser. Use New / Save / Save As / Duplicate / Delete in the header; the chip shows Saved or Unsaved changes. For a synced, backed-up library, Export each design as a .json into an iCloud Drive folder and Import it on any machine. Backup / Restore handle the whole library at once.

The driver dropdown is at the top of the Drive unit panel; its Thiele-Small parameters show beneath (shorthand, value, description). Add or edit drivers in the Drivers tab — New / Save / Duplicate / Delete plus JSON Export / Import. Edited drivers flow through to every design that uses them.

Toggle Ported / Sealed. For vented boxes, specify the alignment by Tuning Fb or by Port length — the other is computed. Inapplicable fields grey out automatically. The blue panel shows computed port area, equivalent diameter, length or Fb, and peak air velocity. Optimise offers Flatten Fb (vented) or Target Qtc to Vb (sealed).

Set the input power. Amp drive: Power-limited (default) treats the filters as active line-level EQ ahead of a power-capped amplifier, so a boost trades headroom rather than pushing excursion past the cap. Constant voltage shows filters as raw gain. Filters: high-pass and low-pass (Butterworth or Linkwitz-Riley, up to 48 dB/oct), parametric EQ, low and high shelves with Q, and a Linkwitz transform for sealed boxes.

Power convention: the power input is defined as watts into Re+Rs — the drive voltage is V = √(P·(Re+Rs)). Manufacturer AES/nominal ratings use the nominal impedance, so a given wattage here drives ~1–2 dB less voltage than "catalogue watts". Cone excursion, port air velocity and amplifier current are peak values for a sine at that voltage.

The SPL plot is the large chart, with F3/F6/F10 marked on the curve. Set fixed Y and X extents (or press Auto) so changes stay visible. Below sit excursion (with Xmax and Xmech limit lines), port velocity, group delay, step response, impedance and amplifier current. Hover any chart to read exact values.

Baffle: enter baffle size and driver position, choose Horizontal or Vertical, and an angle (or All 0–90°) to see directivity, with its own extents. Compare: overlay up to four saved designs on any metric. PDF (top right) builds a one-page build summary — enclosure, full port spec, driver, performance, the power at which the driver reaches Xmax (with and without filters), and the key plots — then opens a print view; choose Save as PDF.

Validated: the lumped-parameter engine (sealed + vented) reproduces the P&G spreadsheet reference bit-exactly — SWMini V3 (78 L, Fb 40.26 Hz) gives F3 55.72 Hz / 98.20 dB with the spreadsheet driver data, and F3 59.22 Hz / 98.68 dB with the current datasheet driver library. A regression suite (tests/engine-regression.js, 33 assertions) locks these numbers — run it with node before shipping any engine change. Port end corrections are physically validated (Jul 2026, DATS impedance sweeps on the SWMini at 12 °C, three flush port lengths + the V4 flared port + sealed + free-air/added-mass driver measurement): flush measured 0.431·d per end vs the 0.425 constant; flared measured 0.38–0.45·d per end vs overall length, mid-band on the 0.425 constant; the pre-v0.16 flared value of 0.25 is refuted. Supported tuning accuracy ≈ ±2% in Fb for a tight enclosure. Full write-up: Impedance Tests/Port End-Correction Validation — Results.md.

Calculated from first principles: box/port tuning (Helmholtz, end-corrected — Flush 0.85a, Free 0.61a, Flared 0.85a per JAES port literature), frequency response, cone excursion (peak), impedance, group delay and step response including filter phase, port air velocity (peak, per port, incl. filters), multi-driver scaling, filter/EQ responses (Butterworth, Linkwitz-Riley, RBJ biquads, Linkwitz transform), piston directivity and array factor.

Modelled / indicative (labelled in-app where active): port-resonance peak height; box-mode amplitudes; fill/leak Q values and the fill compliance factor; thermal compression (steady-state, no time constants); baffle diffraction (first-order edge model, not BEM — this also carries the free-space baffle-step behaviour); chuffing thresholds (17–34 m/s peak, flare-dependent); the thermal Max-SPL ceiling (flat rated power, no spectral weighting).

Known limits: the model is linear — port compression (above the dotted 17 m/s onset on the Max-SPL chart), Bl(x)/Cms(x) nonlinearity and suspension creep are not modelled, so Max-SPL is optimistic near the limits. Above Xmax the dashed Xmech ceiling shows the kinematic output limit at the mechanical stop (exact, since SPL at a given displacement is pure kinematics); the power to reach it is reported as a range — linear extrapolation up to +≈3 dB large-signal compression allowance for Bl droop and suspension stiffening — and is burst-only territory with >10% distortion. Voice-coil inductance is a first-order jωLe model (optional toggle; real coils are semi-inductive). Drive power is defined as watts into Re+Rs. Bandpass and passive-radiator enclosures are not supported.

Enclosure Designer — a loudspeaker enclosure modelling tool. Created by Jack Pitt.

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