18 Sound 21LW400

21.5" · 8 Ω · 1600 W · 99.5 dB · datasheet ↗

Thiele-Small parameters

Nominal size	21.5"
Impedance	8 Ω
Fs	28 Hz
Qts	0.234
Qes	0.24
Qms	9.32
Vas	385 L
Sd	1662 cm²
Xmax	9.3 mm
Re	5 Ω
Bl	34.5 T·m
Mms	324.9 g
Pe	1600 W
Sensitivity	99.5 dB

Alignment hint

EBP	117 · ported
Sealed Vb (Qtc ≈ 0.71)	≈ 47.3 L

EBP > 100: favours a ported (bass-reflex) alignment.

Rules of thumb from T/S parameters only. Verify against a real simulation before cutting wood.

Substitute candidates

Driver	Fs (Hz)	Qts	Vas (L)	Xmax (mm)	Sens (dB)	Fit	Notes	Compare
RCF LF 21N451 v2017	30 +2	0.259 +0.02	375 -10	8.6 -0.7	99.3 -0.2	close	Xmax 8.6 mm < 9.3 mm: lower excursion-limited SPL	+
RCF LF 21N451	30 +2	0.239 =	440 +55	8.9 -0.4	100.4 +0.9	close	Xmax 8.9 mm < 9.3 mm: lower excursion-limited SPL	+
Beyma 21LEX1600/Nd	30 +2	0.272 +0.04	394 +9	9.3 =	99.3 -0.2	close		+
B&C 21 DS 115	30 +2	0.234 =	269 -116	7.6 -1.7	98.7 -0.8	usable	Xmax 7.6 mm < 9.3 mm: lower excursion-limited SPL	+
18 Sound 21NLW9000C	29 +1	0.248 +0.01	257 -128	8.1 -1.2	100.5 +1	usable	4 Ω vs 8 Ω: amp load changes · Xmax 8.1 mm < 9.3 mm: lower excursion-limited SPL	+
Beyma 21QLEX1600/Fe	30 +2	0.281 +0.05	309 -76	8.4 -0.9	98.1 -1.4	usable	Xmax 8.4 mm < 9.3 mm: lower excursion-limited SPL	+
Beyma 21PW1400FE	30 +2	0.343 +0.11	401.5 +16.5	10 +0.7	98.6 -0.9	usable		+
B&C 21 SW 150	29 +1	0.261 +0.03	254 -131	7.5 -1.8	99.4 -0.1	usable	4 Ω vs 8 Ω: amp load changes · Xmax 7.5 mm < 9.3 mm: lower excursion-limited SPL	+
LaVoce SAN214.50LD vp	30 +2	0.223 -0.01	250 -135	7.2 -2.1	98.4 -1.1	usable	Xmax 7.2 mm < 9.3 mm: lower excursion-limited SPL	+
RCF LF 21X451	28 =	0.369 +0.13	385 =	13 +3.7	97 -2.5	usable		+

Compare the closest 3 against the 21LW400 →

Ranked on parameter similarity only (Qts, Fs, Vas, Xmax, sensitivity). Same nominal size required. A hint, not a simulation, model the swap before cutting or buying.

Used in enclosures (0)

No enclosure in the catalog uses this driver yet.