Altec 421-8LF

15" · 8 Ω · 150 W · 99.9 dB · datasheet ↗

Thiele-Small parameters

Nominal size	15"
Impedance	8 Ω
Fs	27.5 Hz
Qts	0.254
Qes	0.28
Qms	2.75
Vas	576 L
Sd	825.8 cm²
Xmax	1.3 mm
Re	5.5 Ω
Bl	13.7 T·m
Mms	55.6 g
Pe	150 W
Sensitivity	99.9 dB

Alignment hint

EBP	98 · flexible
Sealed Vb (Qtc ≈ 0.71)	≈ 85.3 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 421-16LF	27 -0.5	0.246 -0.01	600.3 +24.3	1.3 =	96.8 -3.1	close	16 Ω vs 8 Ω: amp load changes	+
Altec 619-8A	24.6 -2.9	0.241 -0.01	621.3 +45.3	1.3 =	98.6 -1.3	close	75 W vs 150 W: lower power handling	+
Altec 604-8H	28.1 +0.6	0.269 +0.02	558.7 -17.3	3.8 +2.5	99.3 -0.6	close	100 W vs 150 W: lower power handling	+
Altec 421-8H-II vp1	26.9 -0.6	0.272 +0.02	479.3 -96.7	1.3 =	98.6 -1.3	close		+
Altec 604-8G	25.8 -1.7	0.252 =	624.4 +48.4	3.8 +2.5	98.7 -1.2	close	100 W vs 150 W: lower power handling	+
Supravox 400 EXC Ag 13V	25.3 -2.2	0.253 =	555.6 -20.4	5 +3.7	98.7 -1.2	close		+
Altec 421-8H-II vp2	25.6 -1.9	0.28 +0.03	501.7 -74.3	1.3 =	98.2 -1.7	close		+
Audio Nirvana CLASSIC 15 FERRITE	24.7 -2.8	0.271 +0.02	551.3 -24.7	1.1 -0.2	97.3 -2.6	usable	80 W vs 150 W: lower power handling · Xmax 1.1 mm < 1.3 mm: lower excursion-limited SPL	+
Altec 515-8LF	27.4 -0.1	0.255 =	470.1 -105.9	5.1 +3.8	98.4 -1.5	usable		+
Great Plains Audio 515-8LF GPA	27.4 -0.1	0.255 =	470.1 -105.9	5.1 +3.8	98.4 -1.5	usable		+

Compare the closest 3 against the 421-8LF →

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.