Twin 200 mm drivers hidden in a wall
ISW-4 needs a larger opening and a tall rear enclosure.
The single Bowers & Wilkins ISW-4 subwoofer fits a 485 × 255 mm wall cut-out. Its baffle measures 494 × 264 mm and is 21 mm thick; behind it, the sealed back box occupies 1406 × 345 × 86 mm. The difference between visible face and actual volume is decisive: reserve a wall cavity more than 1.4 metres long before closing the structure.
Key features
- 485 × 255 mm cut-out; 494 × 264 × 21 mm baffle.
- Sealed 1406 × 345 × 86 mm back box, 27.5 litres.
- Twin 200 mm woofers; 8-ohm nominal impedance (6.3-ohm minimum); 250 W.
- CDA-4D amplifier required; paintable frame and grille.
Drivers and power
Two long-throw 200 mm paper and Aramid Fibre woofers move more air than ISW-3's twin 165 mm units. The braced MDF back box has a 27.5-litre volume. This passive subwoofer requires a separate CDA-4D amplifier and speaker cable from the rack. The -3 dB response is 25 to 222 Hz and the -6 dB range extends from 19 to 400 Hz.
Structural dimensions
Nominal impedance is 8 ohms, with a 6.3-ohm minimum, and the power rating is 250 W. The front assembly weighs 6.4 kg and the back box 9.6 kg. Frame and grille are paintable. Reserve the box's full length between studs, check support for the baffle and route cable to CDA-4D before finishing the wall: the 485 × 255 mm opening is only the visible final cut.
The back box is a separate element from the front panel, rather than merely clearance behind the two cones. The wall must contain its full 1406 mm height, 345 mm width and 86 mm depth. It is best allowed for when the stud layout is designed. Once installed, the larger baffle and paintable grille remain visible; the 27.5-litre acoustic enclosure remains hidden in the structure after fitting.
