Speaker box calculator — sealed response comparison & panel plan
Turn small-signal driver parameters into two ideal sealed-box response curves and a measured rectangular cabinet scenario. Keep the net air volume, occupied-volume allowance and butt-joint panel dimensions together in downloadable files.
Speaker Enclosure Studio
Choose your inputs, or load the working example to explore the result. Your files stay on this device.
Supported scope: Ideal sealed-box response only, from 5–1000 Hz. The separate Helmholtz circular-port length is a geometric reference; no vented frequency response, port velocity, excursion, power handling, SPL or room simulation is claimed. · One rectangular cabinet, uniform wall thickness and simple butt joints. No driver holes, recesses, kerf, bracing design, structural approval or actual driver-fit verification. The PDF is a dimensioned reference; the panel SVG has millimeter dimensions. · Net volumes 1–1000 L; supplied displacement 0–100 L. Original files stay unchanged; saved project JSON up to 15 KB. No automatic persistence or account.
Your inputs
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Your result
Review your output, then save it to your device.
Make the next step clear.
Your findings, assumptions and next steps will appear here after you run the check.
Speaker Enclosure Studio · https://enclosure.kitforma.com/ · KitForma
Compare two net volumes with Qtc, Fc and F3
Dimensioned six-panel plan and separate port reference
Editable project, real PDF, SVG and numerical CSV
Understand the evidence.
Focused guides explain the rules, the edge cases and the checks worth doing before you act.
Compare sealed volumes without confusing Qtc and F3
Read a transparent small-signal model and retain its assumptions.
Read the guide ↗Field guide / 02Turn net volume into a butt-joint panel plan
Understand the dimensions and occupied-volume allowance before cutting.
Read the guide ↗Field guide / 03Use the separate circular-port reference carefully
Keep acoustic effective length, physical length and displacement distinct.
Read the guide ↗Before you start
Does the response chart model a ported box?
No. Both curves are ideal sealed-box responses. A separate optional Helmholtz calculation estimates the physical length of one circular port for the selected net volume, tuning and end correction. It does not turn the sealed response into a vented simulation.
How are Fc, Qtc and F3 calculated?
Fc = Fs × sqrt(1 + Vas/Vb), and Qtc = Qts × sqrt(1 + Vas/Vb). The second-order high-pass response is evaluated numerically across 5–1000 Hz. F3 is solved analytically at half power relative to the high-frequency asymptote; it is not necessarily equal to Fc.
What is the difference between net and gross volume?
Net is the modeled air volume. The plan adds your total occupied-volume allowance to obtain the internal rectangular volume. Driver baskets, braces, ports and other objects must be accounted for by you. A missing or inaccurate allowance changes the real air volume.
Which joints does the cut list assume?
Front and back are full external width by height. The two sides are full external height by internal depth. Top and bottom fit between the sides and front/back: internal width by internal depth. Thickness is uniform. No kerf, rebates, holes or material-strength allowance is added.
Can the tool tell me the loudest or safest design?
No. It compares ideal small-signal response and dimensions. It has no excursion, thermal, port-speed, baffle diffraction, room or vehicle model, and it does not approve construction. A real design needs measured driver data and verification of the intended assembly.
Can I edit and reopen the design?
Yes. Change the two net volumes in the result and prepare new files, or save and reopen the project JSON. The initial report downloads describe the original submitted run. No hidden automatic browser backup is created.
Sources & assumptions
Formats, algorithms and supported features are documented below. Check the stated scope and inspect your output before using it.
- Linkwitz — Closed-box analysis ↗
Small-signal closed-box modeling and the limitations of equalizing a real driver.
- UNSW Physics — Helmholtz resonance ↗
Lumped acoustic resonance, effective neck length and end effects.
- Analog Devices — Linkwitz closed-box circuit ↗
Second-order system response and measured resonance/Q context.
Reviewed 2026-10-19. Read our methodology or report an issue.