Kinnara
SB Acoustics' open-source sealed two-way floorstander: an 8-inch paper-cone woofer under a 25.4 mm aluminium dome, in a 1098 mm walnut cabinet whose drawings are published in full.
About the Kinnara
The Kinnara is one of the designs SB Acoustics publishes as open source, alongside Tifa 6, Tifa 8 and Bromo. The drawings are in the open — overall dimensions, panel thicknesses, rebate depths, driver cut-outs, even the damping cut to size. Take them to a cabinet shop, or buy the cabinets ready-made from the factory and skip the sawdust.
It is a sealed two-way floorstander. Per cabinet: one 8″ SB20PFCS30-7 paper-cone woofer and one SB26ADC-C000-4 25.4 mm aluminium dome, crossed at 2300 Hz. SB Acoustics rates the finished system at 45–25,000 Hz and 6 Ω nominal. The cabinets are supplied as a pair in walnut veneer matt, without grilles, and the crossover comes as a set alongside them.
No exotic cone material and no origin story attached to it. A paper cone, an aluminium dome, and a drawing anyone can read — which is a fair description of how most good speakers were made before the marketing department got involved.
Its lines are drawn tall and narrow: 1098 mm high on a footprint 330 mm across. Inside, a slanted panel set at 10° means no two opposite surfaces run parallel down the length of the box.
Specifications
Every figure here is SB Acoustics’ own, published for the finished system.
| Specification | Value |
|---|---|
| Frequency range | 45 – 25,000 Hz |
| Sensitivity (2.83 V / 1 m) | 84 dB |
| Nominal impedance | 6 Ω |
| Maximum SPL | 105 dB |
| Recommended amplifier | 100 – 200 W |
| Crossover frequency | 2300 Hz |
| Enclosure type | Sealed |
| Drive units | SB26ADC-C000-4 and 8″ SB20PFCS30-7 |
The sealed alignment is the design decision that shapes everything else here. It is why the box is only 330 mm across, why the roll-off below 45 Hz is gradual, and why SB Acoustics asks for 100–200 W behind an 84 dB speaker. Sealed boxes trade sensitivity for control; the amplifier makes up the difference.
Woofer — 8″ SB20PFCS30-7
A 30.5 mm voice coil on a paper cone with a rubber surround, in a round-mount injection chassis. SB Acoustics lists it for acoustic-suspension use, which is precisely the job it does here: a Qts of 0.66 and an Fs of 39 Hz are the numbers of a driver drawn for a sealed box. SB Acoustics lists the part at 7 Ω nominal, and that is the figure the design is built on.
| Parameter | Value | Parameter | Value |
|---|---|---|---|
| Nominal impedance | 7 Ω | Free-air resonance (Fs) | 39 Hz |
| Sensitivity (2.83 V / 1 m) | 88 dB | Total Q (Qts) | 0.66 |
| Equivalent volume (Vas) | 59.5 litres | Moving mass (Mms) | 19.6 g |
| Force factor (Bl) | 5.6 Tm | Piston area (Sd) | 222 cm² |
| Voice coil diameter | 30.5 mm | Linear travel (p-p) | 11 mm |
| Rated power | 40 W | Net weight | 0.96 kg |
Paper is stiff for its mass and self-damping, which is why it has stayed in serious drivers for eighty years however unfashionable it looks on a specification sheet. The full parameter set for this and every other model we carry is in the SB Acoustics core-range catalogue.
Tweeter — SB26ADC-C000-4
A 25.4 mm aluminium dome on a ferrite motor, in an injection-moulded faceplate. Its free-air resonance is 680 Hz and the Kinnara crosses to it at 2300 Hz — better than an octave and a half clear of resonance, which is where a dome should be asked to start work. Rated at 120 W, 90 dB sensitivity, 4 Ω.
| Parameter | Value | Parameter | Value |
|---|---|---|---|
| Nominal impedance | 4 Ω | Free-air resonance (Fs) | 680 Hz |
| Sensitivity (2.83 V / 1 m) | 90 dB | Total Q (Qts) | 1.11 |
| Voice coil diameter | 25.4 mm | Flux density | 1.15 T |
| Rated power | 120 W | Net weight | 0.5 kg |
Aluminium, where the domes higher up the SB Acoustics range are textile and beryllium. On an open-source design meant to be built at home, a well-behaved dome crossed an octave and a half clear of its resonance is the engineering answer.
The cabinet, as drawn
Every figure here is read off SB Acoustics' own drawing. Two of them check each other: 294 mm of internal width plus two 18 mm side panels is 330 mm, which is exactly the overall width given.
| Dimension | As drawn |
|---|---|
| Overall height | 1098 mm |
| Overall width | 330 mm |
| Overall depth | 270 mm |
| Panel thickness | 18 mm |
| Internal width | 294 mm |
| Internal panel | Set at 10° |
| Tweeter cut-out | Ø100.7 mm, Ø88.5 mm bolt circle, four Ø7 mm holes, rebated |
| Woofer cut-out | Ø189 mm, Ø207 mm bolt circle, six Ø7 mm holes at 45°, rebated |
Both cut-outs are rebated, so the driver frames finish flush with the baffle. The drawing takes its dimensions before painting, depth excepted, and allows half a millimetre for the paint.
Every piece of damping is drawn and dimensioned
Most plans stop at “line the box with wadding”. This one gives you four pieces of 20 mm Dacron, cut to size, each with the surface it belongs on — and a cut pattern for laying them out on the roll.
| Piece | Size | Qty | Where it goes |
|---|---|---|---|
| A | 1300 × 290 mm | 1 | One layer over the top and back |
| B | 800 × 290 mm | 1 | One layer over piece A and the back |
| C | 800 × 180 × 40 mm | 2 | Two layers, left and right side panels |
| D | 900 × 125 mm | 2 | Two layers, over piece B and the front |
All four are specified as 9 oz white Dacron, 20 mm thick. Piece C is a taper — 180 mm at one end, 40 mm at the other — because it follows the slanted internal panel.
The cabinets arrive finished
Every cabinet in the photographs on this page is what turns up on the pallet. They are cut, assembled and finished at the same works that makes the drivers, on the same machines, to the same tolerances — so the job in front of you is the acoustics: mount the drivers, wire the crossover, fit the damping.
One finish, chosen to suit the design: walnut veneer, matt, on a set of two cabinets. The Kinnara is drawn to show its drivers, and the set is supplied without grilles.
Tell us which finish you want when you enquire and we will confirm it against the current factory list before anything is ordered.
Going deeper
The most interesting thing about the Kinnara is not on its spec sheet. There is a 1000 µF capacitor in series with the woofer, and it is not a filter — it is the bass alignment. It turns the sealed box from second order to third, flattens the resonance hump and removes sub-30 Hz excursion. It is also why SB had to build a special woofer for this kit, with a third of the magnet removed to raise Qts from 0.37 to 0.66.
We also built a pair in a ready-made cabinet about a third smaller than SB’s drawing and took them to Singapore’s Noising 2026 DIY meet. It cost us less than it should have — for reasons that follow directly from that capacitor.
Come and listen.
Bring your favourite tracks. Leave with something you'll keep for decades. No pressure, no commission-chasing.