← Back to Scan-Speak - 7" Illuminator Mid-Woofer - 18WU/4741T00
Where the figures for 18WU/4741T00 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 18WU/4741T00 page came from.
- 9 from Scan-Speak's product page
- 28 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 | Illuminator | NB Audio's listing |
| Power handling (RMS) | 70 W | Maker's datasheet |
| Power handling (program) | 150 W | Maker's datasheet |
| Sensitivity | 87.2 dB | Maker's product page |
| Suggested alignment | Either | NB Audio's listing |
| Frequency range | fs – 4,000 Hz | Maker's datasheet |
Thiele/Small parameters
| Resonant frequency (Fs) | 34 Hz | Maker's product page |
|---|---|---|
| DC resistance (Re) | 3.3 Ω | Maker's product page |
| Minimum impedance (Zmin) | 4.6 Ω | Maker's datasheet |
| Voice coil inductance (Le) | 0.4 mH | Maker's datasheet |
| Mechanical Q (Qms) | 3.76 | Maker's datasheet |
| Electrical Q (Qes) | 0.39 | Maker's datasheet |
| Total Q (Qts) | 0.36 | Maker's product page |
| Equivalent volume (Vas) | 38.4 L | Maker's product page |
| Compliance (Cms) | 1.2 mm/N | Maker's datasheet |
| Moving mass (Mms) | 19.1 g | Maker's datasheet |
| Mechanical resistance (Rms) | 1.1 kg/s | Maker's datasheet |
| Force factor (Bl) | 5.9 T·m | Maker's product page |
| Effective piston area (Sd) | 154 cm² | Maker's product page |
| Linear excursion (Xmax, one-way) | 9 mm | Maker's datasheet |
| Mechanical excursion (Xmech) | 16 mm | Maker's datasheet |
| Displacement volume (Vd) | 138.6 cm³ | Worked out from the maker's figures |
| Efficiency bandwidth product (EBP) | 87.18 | Worked out from the maker's figures |
| Effective piston diameter (D) | 140 mm | Maker's datasheet |
| Impedance at resonance (Zo) | 31.9 Ω | Maker's datasheet |
Motor
| Voice coil height | 8 mm | Maker's datasheet |
|---|---|---|
| Air gap height | 20 mm | Maker's datasheet |
| Voice coil layers | 4 | Maker's datasheet |
Mounting
| Overall diameter | 184 mm | Maker's datasheet |
|---|---|---|
| Cutout diameter (suggested) | ≈ 158.7 mm | My estimate, from the maker's drawing |
| Mounting depth | 104.8 mm | Maker's datasheet |
| Volume displaced by driver | 0.45 L | Maker's datasheet |
| Voice coil diameter | 42 mm | Maker's datasheet |
| Weight | 1.7 kg | Maker's datasheet |
Materials
| Cone | Sandwich Paper | Maker's product page |
|---|---|---|
| Magnet | Neodymium | Maker's product page |
Typical box tunings
| Closed box: box volume | 17 L | Maker's datasheet |
|---|---|---|
| Closed box: corner frequency | 61 Hz | Maker's datasheet |
| Vented box: box volume | 35 L | Maker's datasheet |
| Vented box: box resonance | 35 Hz | Maker's datasheet |
| Vented box: corner frequency | 35 Hz | Maker's datasheet |
Not on file: Bolt circle, Flange thickness. 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: Datasheet