SB Acoustics SB23NBACS45-4
woofer · EBP 66 → suits either box · nominal (full) — SB Acoustics datasheet (https://sbacoustics.com/wp-content/uploads/2026/05/8-inch-SB23NBACS45-4.pdf)
Thiele/Small parameters
| Fs (resonance) | 23 Hz |
| Qts | 0.33 |
| Qes / Qms | 0.35 / 5.4 |
| Vas | 95.0 L |
| Re / nominal Z | 3.3 Ω / 4 Ω |
| Xmax | — |
| Sensitivity | 87.0 dB (1 W/1 m, calc); 90 dB (2.83 V/1 m, mfr) |
| Power handling | 60 W |
Published (nominal) values, params full — verify by measurement (DATS/REW) before building.
Datasheet (PDF) ↗ — manufacturer-hosted
Recommended enclosures
| Sealed (Qtc 0.707) — Vb | 26.5 L |
| Sealed — Fc / F3 | 49.3 / 49.3 Hz |
| Ported (suggested) — Vb | 49.0 L |
| Ported — Fb / F3 | 28.2 / 30.2 Hz |
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About this driver
The SB Acoustics SB23NBACS45-4 is a 8″ woofer with a free-air resonance of 23 Hz and a total Q (Qts) of 0.33. Its efficiency-bandwidth product (EBP) of 66 points toward either alignment. In a 26.5 L sealed box it reaches an F3 of 49.3 Hz (Qtc 0.707); a suggested 49.0 L box tuned to 28.2 Hz extends to about 30.2 Hz. See the sealed vs ported guide for how to choose.
Recommended partners
modeled estimateThe tweeters below pair well with the SB Acoustics SB23NBACS45-4 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.
- Seas M64F001Good match· 92/100
Suggested crossover 993 Hz (4th-order, Linkwitz-Riley)
Build this pair → - Tang Band 75-1558SHGood match· 92/100
Suggested crossover 993 Hz (4th-order, Linkwitz-Riley)
Build this pair → - Tang Band W8-2314Good match· 92/100
Suggested crossover 993 Hz (4th-order, Linkwitz-Riley)
Build this pair → - Wavecor TW030WA05Good match· 89/100
Suggested crossover 993 Hz (4th-order, Linkwitz-Riley)
Build this pair → - Wavecor TW030WA06Good match· 89/100
Suggested crossover 993 Hz (4th-order, Linkwitz-Riley)
Build this pair → - Seas MR18REX-XFGood match· 89/100
Suggested crossover 993 Hz (4th-order, Linkwitz-Riley)
Build this pair →
Modeled estimate from T/S + geometry — no measurements. The verdict is robust; it improves with measured FRD/ZMA data.