Altec 421-8H-II
Thiele-Small parameters
| Nominal size | 15" |
|---|---|
| Impedance | 8 Ω |
| Fs | 38.7 Hz |
| Qts | 0.242 |
| Qes | 0.27 |
| Qms | 2.3 |
| Vas | 261.4 L |
| Sd | 825.8 cm² |
| Xmax | 1.3 mm |
| Re | 5.5 Ω |
| Bl | 17.5 T·m |
| Mms | 61.9 g |
| Pe | 150 W |
| Sensitivity | 101.1 dB |
Alignment hint
| EBP | 143 · ported |
|---|---|
| Sealed Vb (Qtc ≈ 0.71) | ≈ 34.7 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 |
|---|---|---|---|---|---|---|---|---|
| Tesla ARM 9408 | 35 -3.7 | 0.248 +0.01 | 260 -1.4 | 1.5 +0.2 | 99.6 -1.5 | close | 75 W vs 150 W: lower power handling | + |
| JBL 2135 | 40 +1.3 | 0.253 +0.01 | 297.3 +35.9 | 1.5 +0.2 | 101.5 +0.4 | close | + | |
| Altec 418-8LF vp CF2 | 36.3 -2.4 | 0.254 +0.01 | 230.3 -31.1 | 1.3 = | 99.7 -1.4 | close | + | |
| Altec 3156 | 38 -0.7 | 0.24 = | 246.4 -15 | 3.8 +2.5 | 99.8 -1.3 | close | + | |
| Great Plains Audio 3156 GPA | 38 -0.7 | 0.24 = | 246.4 -15 | 3.8 +2.5 | 99.8 -1.3 | close | + | |
| PD 153ERC002 | 38 -0.7 | 0.249 +0.01 | 263 +1.6 | 6.8 +5.5 | 100.9 -0.2 | close | + | |
| Precision Devices 153ERC002 | 38 -0.7 | 0.249 +0.01 | 263 +1.6 | 6.8 +5.5 | 100.9 -0.2 | close | + | |
| P.Audio WN-15N | 39.8 +1.1 | 0.251 +0.01 | 286.8 +25.4 | 3.5 +2.2 | 102.1 +1 | close | + | |
| JBL K130 | 40 +1.3 | 0.253 +0.01 | 297.3 +35.9 | 3.6 +2.3 | 101.5 +0.4 | close | + | |
| Electro-Voice EVM-15L | 43 +4.3 | 0.238 = | 245 -16.4 | 2.9 +1.6 | 102.8 +1.7 | close | 100 W vs 150 W: lower power handling | + |
Compare the closest 3 against the 421-8H-II →
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.