Focal 40KX

15" · 8 Ω · 500 W · 89.2 dB · datasheet ↗

Thiele-Small parameters

Nominal size	15"
Impedance	8 Ω
Fs	34.6 Hz
Qts	0.82
Qes	0.97
Qms	5.3
Vas	64.8 L
Sd	804.3 cm²
Xmax	5.6 mm
Re	4.2 Ω
Bl	16.7 T·m
Mms	295.9 g
Pe	500 W
Sensitivity	89.2 dB

Alignment hint

EBP	36 · sealed
Sealed Vb (Qtc ≈ 0.71)	Qts too high

EBP < 50: favours a sealed (closed) 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
Rockville 819216020739	33 -1.6	0.886 +0.07	70.6 +5.8	12.9 +7.3	92.1 +2.9	usable	4 Ω vs 8 Ω: amp load changes	+
Rockville W15K9D4	33 -1.6	0.886 +0.07	70.6 +5.8	12.9 +7.3	92.1 +2.9	usable	4 Ω vs 8 Ω: amp load changes	+
MTX Audio T815-22	32.3 -2.3	0.635 -0.18	57 -7.8	6.1 +0.5	90 +0.8	usable	4 Ω vs 8 Ω: amp load changes	+
DD Audio 615 D2	32.3 -2.3	0.689 -0.13	81.6 +16.8	5 -0.6	90.5 +1.3	usable	300 W vs 500 W: lower power handling · Xmax 5 mm < 5.6 mm: lower excursion-limited SPL	+
Monacor RAPTOR 15	39 +4.4	0.696 -0.12	56 -8.8	7.4 +1.8	92 +2.8	usable	4 Ω vs 8 Ω: amp load changes	+
Monacor RAPTOR 15 MK2	39 +4.4	0.696 -0.12	56 -8.8	7.4 +1.8	92 +2.8	usable	4 Ω vs 8 Ω: amp load changes	+
MTX Audio T612S-22	33.6 -1	0.602 -0.22	58.9 -5.9	7.4 +1.8	91.2 +2	usable	4 Ω vs 8 Ω: amp load changes	+
Ground Zero GZRW 15XSPL D2	34.1 -0.5	0.59 -0.23	63.3 -1.5	11.3 +5.7	91.1 +1.9	usable	4 Ω vs 8 Ω: amp load changes	+
MTX Audio TH9515.44	31.9 -2.7	0.653 -0.17	70 +5.2	6.3 +0.7	93.3 +4.1	usable	2 Ω vs 8 Ω: amp load changes	+
Hertz Audio ES 380.5	32 -2.6	0.9 +0.08	98.8 +34	9 +3.4	87.1 -2.1	usable	4 Ω vs 8 Ω: amp load changes	+

Compare the closest 3 against the 40KX →

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.