Seas RM120
midrange · EBP 180 → suits a ported box · nominal (full) — Seas datasheet (https://www.seas.no/images/stories/lotus/pdfdataheet/rm_120_l0021-04s.pdf)
Thiele/Small parameters
| Fs (resonance) | 72 Hz |
| Qts | 0.35 |
| Qes / Qms | 0.4 / 2.95 |
| Vas | 4.0 L |
| Re / nominal Z | 3 Ω / — |
| Xmax | — |
| Sensitivity | — |
Published (nominal) values, params full — verify by measurement (DATS/REW) before building.
Datasheet (PDF) ↗ — manufacturer-hosted
Recommended enclosures
This is a midrange; Thiele/Small box parameters are not used for enclosure design.
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About this driver
The Seas RM120 is a 4″ midrange with a free-air resonance of 72 Hz and a total Q (Qts) of 0.35. Its efficiency-bandwidth product (EBP) of 180 points toward a ported alignment. See the sealed vs ported guide for how to choose.
Recommended partners
modeled estimateThe tweeters below pair well with the Seas RM120 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 27TBFC/G H1212-06Good match· 84/100
Suggested crossover 2.06 kHz (4th-order, Linkwitz-Riley)
Build this pair → - SB Acoustics SB29RDC-C000-4Good match· 84/100
Suggested crossover 2.06 kHz (4th-order, Linkwitz-Riley)
Build this pair → - Dayton Audio RS28F-4Good match· 84/100
Suggested crossover 2.06 kHz (4th-order, Linkwitz-Riley)
Build this pair → - Dayton Audio EC30-4Good match· 84/100
Suggested crossover 2.06 kHz (4th-order, Linkwitz-Riley)
Build this pair → - Eminence ALPHA-4-4Good match· 84/100
Suggested crossover 2.06 kHz (4th-order, Linkwitz-Riley)
Build this pair → - Eminence ALPHA-4-8Good match· 84/100
Suggested crossover 2.06 kHz (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.