Audio & Speakers
Passive Crossover
fc = 1 / (2π√(LC))
Capacitor and inductor values for 1st–4th order low-pass and high-pass speaker crossover networks.
Design →Subwoofer Box Enclosure Comparison
Vb (sealed / ported / bandpass)
Compare sealed, ported, and bandpass enclosure volumes from Thiele-Small driver parameters side by side.
Design →Subwoofer Vent/Port
L = (23562.5 · d² / (fb² · Vb)) − 0.732d
Port length and minimum diameter to tune a bass-reflex enclosure without chuffing or port noise.
Design →Audio calculators for subwoofer enclosure design and speaker system tuning: sealed and ported box volumes, vent port length and minimum diameter, and 1st-through-4th-order passive crossover networks.
Each tool uses Thiele-Small driver parameters where applicable and ships with worked examples drawn from common woofer specs. Built for car-audio, home-audio, and pro-audio enclosure projects.
When to use these calculators
Use the subwoofer box calculator to compare sealed vs ported vs bandpass enclosure tradeoffs before cutting wood. Use the vent port calculator to size ports for a target tuning frequency without chuffing or port-noise. Use the crossover calculator to spec capacitor and inductor values for 6/12/18/24 dB-per-octave slopes.
These are educational tools — always cross-check against your driver manufacturer's recommended enclosure specs before building.
Frequently Asked Questions
- What's the difference between a sealed and ported subwoofer box?
- A sealed (acoustic suspension) enclosure offers tighter transient response, smaller box volume, and gradual low-end rolloff (12 dB/octave). A ported (bass reflex) enclosure adds a tuned vent for additional output below tuning, with a steeper 24 dB/octave rolloff and a larger box. The Subwoofer Box Enclosure Comparison calculator computes both side by side.
- How do I tune a ported box?
- Port tuning frequency is set by port length, port cross-sectional area, and box internal volume. Lower frequencies need longer ports. The Vent Port calculator solves for length given a target Fb, or for minimum diameter given displacement (Vd) to avoid port noise at high SPL.
- Do these calculators replace box-modeling software?
- For final enclosure design, modeling software (WinISD, BassBox) simulates frequency response, group delay, and excursion — these calculators give you the volumetric and port-length starting point. Use them to spec a box quickly, then verify in a simulator.