RCF LF 21N551
Thiele-Small parameters
| Nominal size | 21.5" |
|---|---|
| Impedance | 8 Ω |
| Fs | 35 Hz |
| Qts | 0.331 |
| Qes | 0.35 |
| Qms | 6.2 |
| Vas | 200 L |
| Sd | 1730 cm² |
| Xmax | 7.7 mm |
| Re | 5.2 Ω |
| Bl | 37.6 T·m |
| Mms | 433.8 g |
| Pe | 2000 W |
| Sensitivity | 97.7 dB |
Alignment hint
| EBP | 100 · flexible |
|---|---|
| Sealed Vb (Qtc ≈ 0.71) | ≈ 56.1 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 |
|---|---|---|---|---|---|---|---|---|
| B&C 21 SW 152 | 32 -3 | 0.297 -0.03 | 198.2 -1.8 | 7.5 -0.2 | 98.9 +1.2 | close | 4 Ω vs 8 Ω: amp load changes · Xmax 7.5 mm < 7.7 mm: lower excursion-limited SPL | + |
| B&C 21 SW 152 v2013 | 32 -3 | 0.297 -0.03 | 200 = | 7.5 -0.2 | 99.5 +1.8 | close | 4 Ω vs 8 Ω: amp load changes · Xmax 7.5 mm < 7.7 mm: lower excursion-limited SPL | + |
| Ciare NDK 21-4 | 28.5 -6.5 | 0.322 -0.01 | 232.4 +32.4 | 8 +0.3 | 97.4 -0.3 | close | 4 Ω vs 8 Ω: amp load changes · 1500 W vs 2000 W: lower power handling | + |
| Ciare NDC 21-5 | 32.2 -2.8 | 0.344 +0.01 | 270.8 +70.8 | 8.8 +1.1 | 97.2 -0.5 | close | 1500 W vs 2000 W: lower power handling | + |
| Eminence NSW6021-6 | 29 -6 | 0.304 -0.03 | 224.6 +24.6 | 10.3 +2.6 | 97.7 = | usable | 4 Ω vs 8 Ω: amp load changes | + |
| Beyma 21SW1600ND | 33 -2 | 0.382 +0.05 | 268 +68 | 8.9 +1.2 | 97.6 -0.1 | usable | + | |
| Dayton Audio PSS545HE-4 VORTEX | 28.8 -6.2 | 0.27 -0.06 | 212.1 +12.1 | 8.6 +0.9 | 97.8 +0.1 | usable | 4 Ω vs 8 Ω: amp load changes | + |
| SB Audience NERO-21SW1100D | 32 -3 | 0.339 +0.01 | 312.6 +112.6 | 8.1 +0.4 | 98.6 +0.9 | usable | 1100 W vs 2000 W: lower power handling | + |
| B&C 21 SW 115 v2015 | 33 -2 | 0.353 +0.02 | 278 +78 | 9.3 +1.6 | 100.6 +2.9 | usable | 4 Ω vs 8 Ω: amp load changes | + |
| P.Audio SD-21 | 41 +6 | 0.412 +0.08 | 200.6 +0.6 | 5.7 -2 | 98.8 +1.1 | usable | 1000 W vs 2000 W: lower power handling · Xmax 5.7 mm < 7.7 mm: lower excursion-limited SPL | + |
Compare the closest 3 against the LF 21N551 →
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.