Port Tuning Calculator

Calculate port tube length and diameter for a ported speaker enclosure tuned to a specific frequency.

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How It Works

Port tuning uses the Helmholtz resonance formula: Lv = (c²·Sp)/(4π²·Fb²·Vb) - 0.825·Dv, where Lv is port length, Sp is port area, Fb is tuning frequency, Vb is box volume, and Dv is port diameter. The 0.825·Dv term is the end correction factor. Port velocity should stay below 15 m/s to avoid chuffing noise — use a larger diameter or multiple ports for high-output applications. Rule of thumb: port area (in²) should be at least equal to Sd (driver area) × Xmax (mm) / 100.