Speaker Box Designer

Turn this on to get a driver's response shape from just Fs, Qts, and Vas — handy for a quick estimate, or a datasheet that doesn't list a full Thiele/Small set. This works because a driver+box's acoustic output shape (SPL and group delay) depends only on the combined total Qts, not on how it splits between electrical and mechanical damping, and not on Sd or Re — but that also means impedance, excursion, absolute SPL, port/line velocity, and Maximum Output Level all genuinely need those, so they're hidden rather than shown from made-up numbers.

Baffle width only affects the Room placement directivity estimate below — it's the enclosure's front panel width, not the driver's own cone size. A baffle wider than the driver stops sound diffracting around to the rear/sides at a lower frequency than the bare driver would.

Near-field reinforcement from specific nearby surfaces. Enable any that apply and set the distance and reflectivity for each — they're modeled independently, so they don't need to match (e.g. 30 cm to a bare back wall, 90 cm to a curtained side wall). Reflectivity is the share of arriving energy the surface bounces back rather than absorbs: bare wall/tile/glass ≈ 90-98%, painted drywall ≈ 85-95%, carpet or heavy curtains ≈ 60-85%, dedicated bass absorption lower still.

Soft furnishings barely affect bass but absorb progressively more as frequency rises, so checking this fades every enabled boundary's reflectivity down toward roughly half its set value by the top of the modeled range, instead of holding it constant across all frequencies.

A separate, smooth low-frequency boost from the room's overall size acting as a pressure chamber — no nulls, and independent of exactly where the speaker sits in the room (unlike Room placement above).

An optional lowpass filter, modeled as an active/electronic crossover placed ahead of the power amplifier (as in a powered subwoofer or an active crossover) — not a passive LC network wired in series with the driver. Because it sits upstream of the amp, it scales the voltage that reaches the driver above cutoff (and therefore SPL, excursion, and port/line-outlet velocity) without adding to the driver+enclosure's own electrical impedance.