B&C 21DS115

21" · 8 Ω · 1700 W · 99 dB · datasheet ↗

Thiele-Small parameters

Nominal size	21"
Impedance	8 Ω
Fs	34 Hz
Qts	0.27
Qes	0.28
Qms	10.2
Vas	204 L
Sd	1620 cm²
Xmax	16.5 mm
Re	5.1 Ω
Bl	39.3 T·m
Mms	404 g
Pe	1700 W
Sensitivity	99 dB

Alignment hint

EBP	121 · ported
Sealed Vb (Qtc ≈ 0.71)	≈ 34.8 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
B&C 21SW152	32 -2	0.3 +0.03	200 -4	15 -1.5	96 -3	close	4 Ω vs 8 Ω: amp load changes · Xmax 15 mm < 16.5 mm: lower excursion-limited SPL	+
RCF LF21N551	35 +1	0.33 +0.06	200 -4	15 -1.5	97 -2	usable	Xmax 15 mm < 16.5 mm: lower excursion-limited SPL	+
Faital PRO 21XL3000	32 -2	0.22 -0.05	223.5 +19.5	17.67 +1.17	98 -1	usable	4 Ω vs 8 Ω: amp load changes	+
18 Sound 21NLW9601	37 +3	0.29 +0.02	175 -29	14 -2.5	98 -1	usable	Xmax 14 mm < 16.5 mm: lower excursion-limited SPL	+
Lavoce SAN215.30	35 +1	0.33 +0.06	200 -4	14.9 -1.6	95.7 -3.3	usable	Xmax 14.9 mm < 16.5 mm: lower excursion-limited SPL	+
18 Sound 21NLW9001	32 -2	0.31 +0.04	244 +40	14 -2.5	98 -1	usable	Xmax 14 mm < 16.5 mm: lower excursion-limited SPL	+
B&C 21DS115	32 -2	0.21 -0.06	219 +15	15 -1.5	100 +1	usable	4 Ω vs 8 Ω: amp load changes · Xmax 15 mm < 16.5 mm: lower excursion-limited SPL	+
Eminence NSW6021-6	29 -5	0.31 +0.04	224.58 +20.58	21 +4.5	97 -2	usable	6 Ω vs 8 Ω: amp load changes	+
Faital PRO 21XL3000	30 -4	0.25 -0.02	284.6 +80.6	17.67 +1.17	98 -1	usable		+
B&C 21SW152	32 -2	0.36 +0.09	200 -4	15 -1.5	96 -3	usable	Xmax 15 mm < 16.5 mm: lower excursion-limited SPL	+

Compare the closest 3 against the 21DS115 →

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 (1)

21" Tapped Hornsubtapped horn