Altec 421-8H-II vp2

15" · 8 Ω · 150 W · 98.2 dB · datasheet ↗

Thiele-Small parameters

Nominal size	15"
Impedance	8 Ω
Fs	25.6 Hz
Qts	0.28
Qes	0.292
Qms	6.944
Vas	501.7 L
Sd	855.3 cm²
Xmax	1.3 mm
Re	5.49 Ω
Bl	15.5 T·m
Mms	79.2 g
Pe	150 W
Sensitivity	98.2 dB

Alignment hint

EBP	88 · flexible
Sealed Vb (Qtc ≈ 0.71)	≈ 93.3 L

EBP 50-100: works in either a sealed or ported 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 421-8H-II vp1	26.9 +1.3	0.272 -0.01	479.3 -22.4	1.3 =	98.6 +0.4	close		+
Audio Nirvana CLASSIC 15 FERRITE	24.7 -0.9	0.271 -0.01	551.3 +49.6	1.1 -0.2	97.3 -0.9	close	80 W vs 150 W: lower power handling · Xmax 1.1 mm < 1.3 mm: lower excursion-limited SPL	+
Fluxmag 1504	25.5 -0.1	0.26 -0.02	530 +28.3	4 +2.7	97 -1.2	close		+
Altec 421-8LF	27.5 +1.9	0.254 -0.03	576 +74.3	1.3 =	99.9 +1.7	close		+
Audio Dynamique AD380PM100	25.5 -0.1	0.26 -0.02	530 +28.3	5 +3.7	97 -1.2	close		+
Monacor SP-380P	23 -2.6	0.27 -0.01	505 +3.3	4 +2.7	96.4 -1.8	close		+
Altec 619-8A	24.6 -1	0.241 -0.04	621.3 +119.6	1.3 =	98.6 +0.4	close	75 W vs 150 W: lower power handling	+
Altec 421-16LF	27 +1.4	0.246 -0.03	600.3 +98.6	1.3 =	96.8 -1.4	usable	16 Ω vs 8 Ω: amp load changes	+
Altec 604-8H	28.1 +2.5	0.269 -0.01	558.7 +57	3.8 +2.5	99.3 +1.1	usable	100 W vs 150 W: lower power handling	+
Supravox 400 EXC Ag 13V	25.3 -0.3	0.253 -0.03	555.6 +53.9	5 +3.7	98.7 +0.5	usable		+

Compare the closest 3 against the 421-8H-II vp2 →

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.