← Back to Scan-Speak - 7" Discovery Mid-Woofer - 18W/4424G00
Where the figures for 18W/4424G00 come from
I take every figure from Scan-Speak's own product page or datasheet where I can. This lists where each figure on the 18W/4424G00 page came from.
- 11 from Scan-Speak's product page
- 32 from Scan-Speak's datasheet
- 2 worked out from Scan-Speak's figures
- 1 my estimate
- 4 from NB Audio's listing
General
| Driver type | Mid-Woofer | NB Audio's listing |
|---|---|---|
| Nominal size | 7" | NB Audio's listing |
| Nominal impedance | 4Ω | Maker's datasheet |
| Series | Discovery | NB Audio's listing |
| Power handling (RMS) | 50 W | Maker's datasheet |
| Power handling (program) | 110 W | Maker's datasheet |
| Sensitivity | 90.9 dB | Maker's product page |
| Suggested alignment | Ported | NB Audio's listing |
| Frequency range | fs – 8,000 Hz | Maker's datasheet |
Thiele/Small parameters
| Resonant frequency (Fs) | 49 Hz | Maker's product page |
|---|---|---|
| DC resistance (Re) | 3.2 Ω | Maker's product page |
| Minimum impedance (Zmin) | 4.1 Ω | Maker's datasheet |
| Voice coil inductance (Le) | 0.47 mH | Maker's datasheet |
| Mechanical Q (Qms) | 4.57 | Maker's datasheet |
| Electrical Q (Qes) | 0.42 | Maker's datasheet |
| Total Q (Qts) | 0.38 | Maker's product page |
| Equivalent volume (Vas) | 24.1 L | Maker's product page |
| Compliance (Cms) | 0.92 mm/N | Maker's datasheet |
| Moving mass (Mms) | 11.4 g | Maker's datasheet |
| Mechanical resistance (Rms) | 0.77 kg/s | Maker's datasheet |
| Force factor (Bl) | 5.2 T·m | Maker's product page |
| Effective piston area (Sd) | 137 cm² | Maker's product page |
| Linear excursion (Xmax, one-way) | 2.8 mm | Maker's datasheet |
| Mechanical excursion (Xmech) | 8 mm | Maker's datasheet |
| Displacement volume (Vd) | 38.36 cm³ | Worked out from the maker's figures |
| Efficiency bandwidth product (EBP) | 116.7 | Worked out from the maker's figures |
| Effective piston diameter (D) | 132 mm | Maker's datasheet |
| Impedance at resonance (Zo) | 38 Ω | Maker's datasheet |
Motor
| Voice coil height | 10.5 mm | Maker's datasheet |
|---|---|---|
| Air gap height | 5 mm | Maker's datasheet |
| Voice coil layers | 2 | Maker's datasheet |
Mounting
| Overall diameter | 179.2 mm | Maker's datasheet |
|---|---|---|
| Cutout diameter (suggested) | ≈ 145.3 mm | My estimate, from the maker's drawing |
| Mounting depth | 72.2 mm | Maker's datasheet |
| Flange thickness | 5.2 mm | Maker's datasheet |
| Bolt circle diameter | 167 mm | Maker's datasheet |
| Mounting holes | 6 | Maker's datasheet |
| Mounting hole diameter | 5.3 mm | Maker's datasheet |
| Volume displaced by driver | 0.28 L | Maker's datasheet |
| Voice coil diameter | 25 mm | Maker's datasheet |
| Weight | 1.1 kg | Maker's datasheet |
Materials
| Cone | Coated Fibreglass | Maker's product page |
|---|---|---|
| Surround | SBR | Maker's product page |
| Basket | Cast Aluminium | Maker's product page |
| Magnet | Ferrite | Maker's product page |
Typical box tunings
| Closed box: box volume | 13 L | Maker's datasheet |
|---|---|---|
| Closed box: corner frequency | 85 Hz | Maker's datasheet |
| Vented box: box volume | 26 L | Maker's datasheet |
| Vented box: box resonance | 48 Hz | Maker's datasheet |
| Vented box: corner frequency | 47 Hz | Maker's datasheet |
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: Datasheet