Fostex FW 505

18" · 8 Ω · 150 W · 94.3 dB · datasheet ↗

Thiele-Small parameters

Nominal size	18"
Impedance	8 Ω
Fs	20 Hz
Qts	0.404
Qes	0.43
Qms	6.7
Vas	860 L
Sd	1300 cm²
Xmax	8.5 mm
Re	7.5 Ω
Bl	19.6 T·m
Mms	174.4 g
Pe	150 W
Sensitivity	94.3 dB

Alignment hint

EBP	47 · sealed
Sealed Vb (Qtc ≈ 0.71)	≈ 416.8 L

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
Altec 3182	18 -2	0.398 -0.01	991.1 +131.1	10.7 +2.2	93.5 -0.8	close		+
McCauley 6174	20 =	0.336 -0.07	733.4 -126.6	15.2 +6.7	95.4 +1.1	usable		+
Altec 3182 vp	20.3 +0.3	0.343 -0.06	1159.7 +299.7	10.2 +1.7	96.5 +2.2	usable		+
JBL 2245H	20 =	0.24 -0.16	821.2 -38.8	8.5 =	97.2 +2.9	usable		+
Zeuz DC181125ip	22.2 +2.2	0.458 +0.05	429.3 -430.7	8.5 =	95 +0.7	usable	4 Ω vs 8 Ω: amp load changes	+
AE Speakers IB18HT-4ohm	18.4 -1.6	0.567 +0.16	632.1 -227.9	16.7 +8.2	94.5 +0.2	usable	4 Ω vs 8 Ω: amp load changes	+
Pyle Audio PPA18 vp	24.2 +4.2	0.39 -0.01	503.2 -356.8	6 -2.5	93.1 -1.2	usable	16 Ω vs 8 Ω: amp load changes · Xmax 6 mm < 8.5 mm: lower excursion-limited SPL	+
Eminence 111712	21.6 +1.6	0.288 -0.12	736.2 -123.8	5.8 -2.7	97.1 +2.8	usable	Xmax 5.8 mm < 8.5 mm: lower excursion-limited SPL	+
AE Speakers IB18HT-8	18.4 -1.6	0.568 +0.16	632.1 -227.9	16.7 +8.2	91.5 -2.8	usable		+
Dibeisi PS1805-8	27.1 +7.1	0.4 =	473.8 -386.2	7 -1.5	96.1 +1.8	usable	Xmax 7 mm < 8.5 mm: lower excursion-limited SPL	+

Compare the closest 3 against the FW 505 →

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.