Description
The SB21SDCN-C000-4 is a 21 mm coated fabric dome tweeter from SB Acoustics, and it’s a compact, high-performance tweeter using a neodymium magnet system. Think of it as the neodymium-powered sibling of the SB21SDC, offering a tighter form factor and slightly different tonal qualities.
Features
- Large surround dome for increased acoustic output
- Copper cap for reduced voice coil inductance and minimum phase shift
- Compact low distortion neodymium motor system
- Non-resonant rear chamber with optimized damping for improved dynamics
- CCAW voice coil for low moving mass
- Long life silver lead wires
- Low resonance frequency
Specs
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- Nominal Impedance 4 Ω
- DC resistance, Re 3.1 Ω
- Voice coil inductance, Le 0.04 mH
- Effective piston area, Sd 4.9 cm2
- Voice coil diameter 20.4 mm
- Voice coil height 1.5 mm
- Air gap height 2.0 mm
- Linear coil travel (p-p) 0.5 mm
- Moving mass incl. air, Mms 0.25 g
- Free air resonance, Fs 850 Hz
- Sensitivity (2.83V/1m) 90 dB
- Mechanical Q-factor, Qms 2.44
- Electrical Q-factor, Qes 2.45
- Total Q-factor, Qts 1.22
- Force factor, Bl 1.3 Tm
- Rated power handling* 40 W
- Magnetic flux density 0.9 T
- Magnet weight 0.01 kg
- Net weight 0.06 kg
* IEC 268-5, high-pass Butterworth, 2600 Hz, 12 dB/oct.
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✅ Key Strengths
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Compact size with high performance – easier to fit in slim or small designs.
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Neodymium motor – smaller but strong, great for saving baffle space.
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Smooth, natural sound – soft dome plus low Fs = great integration.
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Rear damping chamber – helps achieve a low Fs and better transient response.
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Crossover flexibility – can safely cross over around 2 kHz.
⚙️ Ideal Applications
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Slim tower or monitor speakers
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Bookshelf speakers where space is tight
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High-end 2-way DIY systems
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Any design where smooth treble and small form factor are priorities
🔧 Crossover Tips
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Recommended Crossover Point: ~1.8–2.5 kHz (2 kHz is a safe sweet spot)
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Use 12–18 dB/octave slopes for best protection and blend
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Good match with:
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SB13PFC25-4 (5″ woofer)
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SB15NRXC30-4 (5.5″ woofer)
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SB17NRXC35-4 (6.5″ woofer)
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⚖️ Comparison: SB21SDCN vs SB21SDC
| Feature | SB21SDCN-C000-4 | SB21SDC-C000-4 |
|---|---|---|
| Magnet Type | Neodymium | Ferrite |
| Size (Faceplate) | 72 mm | 104 mm |
| Fs | ~950 Hz | ~900 Hz |
| Sensitivity | ~90 dB | ~91 dB |
| Compactness | More compact | Larger |
| Sound Signature | Slightly faster/leaner | Slightly warmer/full |
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