Sine Design

SB Acoustics SB20FRPC30-8

woofer · EBP 84 → suits either box · nominal (full) — SB Acoustics datasheet (https://sbacoustics.com/wp-content/uploads/2022/04/8in-SB20FRPC30-8.pdf)

Thiele/Small parameters

Fs (resonance)39.4 Hz
Qts0.45
Qes / Qms0.47 / 10.1
Vas66.3 L
Re / nominal Z6 Ω / 8 Ω
Xmax
Sensitivity91.2 dB (1 W/1 m, calc); 92 dB (2.83 V/1 m, mfr)
Power handling40 W

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

Datasheet (PDF) ↗ — manufacturer-hosted

Recommended enclosures

Sealed (Qtc 0.707) — Vb45.2 L
Sealed — Fc / F361.9 / 61.9 Hz
Ported (suggested) — Vb95.1 L
Ported — Fb / F335.2 / 32.8 Hz

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About this driver

The SB Acoustics SB20FRPC30-8 is a 8″ woofer with a free-air resonance of 39.4 Hz and a total Q (Qts) of 0.45. Its efficiency-bandwidth product (EBP) of 84 points toward either alignment. In a 45.2 L sealed box it reaches an F3 of 61.9 Hz (Qtc 0.707); a suggested 95.1 L box tuned to 35.2 Hz extends to about 32.8 Hz. See the sealed vs ported guide for how to choose.

Recommended partners

modeled estimate

The tweeters below pair well with the SB Acoustics SB20FRPC30-8 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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