Sine Design

Seas L18RCY-P

woofer · EBP 89 → suits either box · nominal (full) — Seas datasheet (https://www.seas.no/images/stories/prestige/pdfdatasheet/H1085_L18RCY_P_Datasheet.pdf)

Thiele/Small parameters

Fs (resonance)33 Hz
Qts0.31
Qes / Qms0.37 / 2.01
Vas38.0 L
Re / nominal Z5.6 Ω / 8 Ω
Xmax—
Sensitivity87.5 dB (1 W/1 m, calc); 88 dB (2.83 V/1 m, mfr)
Power handling80 W

Published (nominal) values, params full — verify by measurement (DATS/REW) before building.

Datasheet (PDF) ↗ — manufacturer-hosted

Recommended enclosures

Sealed (Qtc 0.707) — Vb9.0 L
Sealed — Fc / F375.3 / 75.3 Hz
Ported (suggested) — Vb15.9 L
Ported — Fb / F343.2 / 47.5 Hz
Open in designer →Use my measured parameters →Buy at Parts Express →

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About this driver

The Seas L18RCY-P is a 6″ woofer with a free-air resonance of 33 Hz and a total Q (Qts) of 0.31. Its efficiency-bandwidth product (EBP) of 89 points toward either alignment. In a 9.0 L sealed box it reaches an F3 of 75.3 Hz (Qtc 0.707); a suggested 15.9 L box tuned to 43.2 Hz extends to about 47.5 Hz. See the sealed vs ported guide for how to choose.

Recommended partners

modeled estimate

The tweeters below pair well with the Seas L18RCY-P in a two-way design — each grade is a modeled estimate of the crossover match, with a suggested crossover point. Open any pair in the guided builder to design the crossover and total the parts.

Modeled estimate from T/S + geometry — no measurements. The verdict is robust; it improves with measured FRD/ZMA data.

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