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Where the figures for SB21SDC-C000-4 come from
I take every figure from SB Acoustics' own product page or datasheet where I can. This lists where each figure on the SB21SDC-C000-4 page came from.
- 20 from SB Acoustics' product page
- 6 from SB Acoustics' datasheet
- 4 worked out from SB Acoustics' figures
- 1 my estimate
- 2 from NB Audio's listing
General
| Driver type | Tweeter | NB Audio's listing |
|---|---|---|
| Nominal size | 0.75" | NB Audio's listing |
| Nominal impedance | 4Ω | Maker's product page |
| Power handling (RMS) | 40 W | Maker's product page |
| Sensitivity | 91 dB | Maker's product page |
Thiele/Small parameters
| Resonant frequency (Fs) | 720 Hz | Maker's product page |
|---|---|---|
| DC resistance (Re) | 3.1 Ω | Maker's product page |
| Voice coil inductance (Le) | 0.04 mH | Maker's product page |
| Mechanical Q (Qms) | 2.41 | Maker's product page |
| Electrical Q (Qes) | 1.55 | Maker's product page |
| Total Q (Qts) | 0.95 | Maker's product page |
| Compliance (Cms) | 0.1954 mm/N | Worked out from the maker's figures |
| Moving mass (Mms) | 0.25 g | Maker's product page |
| Mechanical resistance (Rms) | 0.4693 kg/s | Worked out from the maker's figures |
| Force factor (Bl) | 1.5 T·m | Maker's product page |
| Effective piston area (Sd) | 4.9 cm² | Maker's product page |
| Linear excursion (Xmax, one-way) | 0.5 mm | Maker's product page |
| Displacement volume (Vd) | 0.245 cm³ | Worked out from the maker's figures |
| Efficiency bandwidth product (EBP) | 464.5 | Worked out from the maker's figures |
Motor
| Voice coil height | 1.5 mm | Maker's product page |
|---|---|---|
| Air gap height | 2.5 mm | Maker's product page |
| Magnetic flux density | 1.02 T | Maker's product page |
| Magnet weight | 0.13 kg | Maker's product page |
Mounting
| Overall diameter | 92 mm | Maker's datasheet |
|---|---|---|
| Cutout diameter (suggested) | ≈ 61.0 mm | My estimate, from the maker's drawing |
| Mounting depth | 26.5 mm | Maker's datasheet |
| Flange thickness | 3.3 mm | Maker's datasheet |
| Bolt circle diameter | 80 mm | Maker's datasheet |
| Mounting holes | 4 | Maker's datasheet |
| Mounting hole diameter | 4.2 mm | Maker's datasheet |
| Voice coil diameter | 20.4 mm | Maker's product page |
| Weight | 0.33 kg | Maker's product page |
Materials
| Cone | Fabric | Maker's product page |
|---|
Not on file: Vas. Either the maker doesn't publish it or I haven't found it yet.
What the labels mean
- Maker's product page: copied from the maker's product page.
- Maker's datasheet: read off the maker's own datasheet or drawing.
- Worked out from the maker's figures: Vd = Sd × Xmax, EBP = Fs ÷ Qes.
- My estimate, from the maker's drawing: measured off the maker's drawing, usually within ±0.3 mm (up to ±0.5). The suggested cutout is the basket's width on the drawing plus 1 mm of clearance (1.5 mm on drivers over 200 mm). Measure before you cut.
- NB Audio's listing: how I've filed it in the store.
Check them yourself: SB21SDC-C000-4 Datasheet