Basswright: Speaker Box Design

Speaker box design from the numbers on a driver's spec sheet. Enter the Thiele-Small parameters and see how a sealed, ported, bandpass or passive radiator box will behave before you cut a panel. Basswright handles subwoofer box design too, and works as a ported box calculator with the response curve in front of you instead of a table of numbers.

What you can do
• Type or paste Fs, Qts, Vas, Re, Sd and Xmax from the spec sheet. Missing values are derived and contradictions are flagged. Dual voice coils, several drivers and isobaric pairs are supported.
• Four box types: sealed, vented (ported), 4th-order bandpass and passive radiator. Only the alignments your driver can actually reach are offered.
• A full-screen response curve. Drag the -3 dB point along the curve, or set volume and tuning by hand. Compare up to three variants, A, B and C, on one graph with a cursor readout.
• Limits on the graph, not in a footnote: cone excursion against Xmax, port air speed, impedance, group delay and Max SPL. A strip under the frequency axis shows which limit comes first at your power.
• Input as amplifier power into the final load, as voltage, or as 2.83 V. Subsonic filter, wall fill and cabin gain for a car are included.
• Ports: round, slot or flared, one or several. Physical length with end correction, peak air speed, pipe resonance, and an L-port when the port is longer than the box is deep.
• Box dimensions: net, gross and external volume side by side, with port, driver and bracing taken out. Set your wall thickness, or fix the outside size and let the rest follow. Wedge shape too.
• Cut list: panels with cut-outs and port openings, an exploded view, PDF on A4 or Letter, and CSV. A project can be saved as a file.
• How we calculate: every formula on one screen. Metric or imperial, and each unit can be switched on its own.

For the workshop and the car trunk
Plan a sealed box for a small mid-woofer, a ported box for a 12-inch sub, a bandpass or a passive radiator design, then take the cut list to the saw. Speaker enclosure design stays in one project: tuning, port length and panel sizes move together, so a change in the box volume updates the port and the panels with it.

Private by design
Everything stays on your phone. Basswright has no internet access, asks for no permissions and needs no sign-in. Export a project to a file when you want a copy, or delete all data in Settings.

Please note
Results are estimates from the small-signal Thiele-Small model and the parameters you enter. Real drivers, boxes, rooms and cars differ. Check dimensions, materials, amplifier power and driver limits before you build. The app is not responsible for damaged drivers, amplifiers or materials.

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