← Back to Peerless - 4" HDS Mid-Woofer - 830870
Where the figures for 830870 come from
I take every figure from Peerless' own product page or datasheet where I can. This lists where each figure on the 830870 page came from.
- 29 from Peerless' product page
- 4 from Peerless' datasheet
- 3 worked out from Peerless' figures
- 1 my estimate
- 4 from NB Audio's listing
General
| Driver type | Mid-Woofer | NB Audio's listing |
|---|---|---|
| Nominal size | 4" | NB Audio's listing |
| Nominal impedance | 8Ω | Maker's product page |
| Series | Peerless Woofer | NB Audio's listing |
| Power handling (RMS) | 25 W | Maker's product page |
| Sensitivity | 84.7 dB | Maker's product page |
| Suggested alignment | Ported | NB Audio's listing |
Thiele/Small parameters
| Resonant frequency (Fs) | 100 Hz | Maker's product page |
|---|---|---|
| DC resistance (Re) | 5.3 Ω | Maker's product page |
| Minimum impedance (Zmin) | 6 Ω | Maker's product page |
| Voice coil inductance (Le) | 0.198 mH | Maker's product page |
| Mechanical Q (Qms) | 1.92 | Maker's product page |
| Electrical Q (Qes) | 0.871 | Maker's product page |
| Total Q (Qts) | 0.6 | Maker's product page |
| Equivalent volume (Vas) | 1.73 L | Maker's product page |
| Compliance (Cms) | 0.38 mm/N | Maker's product page |
| Moving mass (Mms) | 6.08 g | Maker's product page |
| Mechanical resistance (Rms) | 1.99 kg/s | Worked out from the maker's figures |
| Force factor (Bl) | 4.93 T·m | Maker's product page |
| Effective piston area (Sd) | 56.8 cm² | Maker's product page |
| Linear excursion (Xmax, one-way) | 5 mm | Maker's product page |
| Mechanical excursion (Xmech) | 7.5 mm | Maker's product page |
| Displacement volume (Vd) | 28.4 cm³ | Worked out from the maker's figures |
| Efficiency bandwidth product (EBP) | 114.8 | Worked out from the maker's figures |
Motor
| Motor efficiency factor (β) | 4.6 (T·m)²/Ω | Maker's product page |
|---|---|---|
| Air gap height | 6 mm | Maker's product page |
| Voice coil winding height | 12 mm | Maker's product page |
| Voice coil layers | 2 | Maker's product page |
| Voice coil wire | CCAW | Maker's product page |
| Magnet size (OD × ID × thickness) | 81 × 36 × 15 mm | Maker's product page |
Mounting
| Overall diameter | 120.4 mm | Maker's datasheet |
|---|---|---|
| Faceplate | Round with two flats, Ø120.4 mm, 106.6 mm across the flats | Maker's datasheet |
| Cutout diameter (suggested) | ≈ 95.8 mm | My estimate, from the maker's drawing |
| Mounting depth | 55.3 mm | Maker's datasheet |
| Flange thickness | 4.5 mm | Maker's datasheet |
| Voice coil diameter | 25.7 mm | Maker's product page |
| Weight | 0.92 kg | Maker's product page |
Materials
| Cone | Polypropylene | Maker's product page |
|---|---|---|
| Surround | NBR | Maker's product page |
| Basket | Cast Aluminium | Maker's product page |
| Magnet | Ferrite | Maker's product page |
Not on file: Bolt circle. 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: Spec Sheet