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Need big sound, slamming bass, and audiophile bass extension, but don’t want to see where it comes from? Then the new ISW-4 in-wall subwoofer is the product for you. Its two long-throw 200mm (8in) drivers allow the ISW-4 to move large volumes of air needed for high-quality low-frequency output but is nicely hidden inside a wall. Powered by a separate audiophile-standard 250W Class D amplifier the SA250 Mk2, the system keeps its cool even when the music movie action is whipping up a storm.


2-year manufacturer's warranty


  • in-wall subwoofer with back-box and matching external amplifier
  • ideal for a discreet home theater or stereo music system

Video Review:

In-Wall Passive Subwoofer:
The Bowers & Wilkins ISW-4 in-wall passive subwoofer features two long-throw 8" paper/aramid fiber cone woofers with rubber surrounds for high-quality, low-frequency bass output that can be hidden away in the wall. The ISW-4 is specifically powered by the included SA250 250W Class D amplifier. The ISW-4 in-wall subwoofer is perfect for both multichannel home theater and 2ch stereo applications.

Gold-Plated Spring-Post Terminals:
The B&W ISW-4 in-wall passive subwoofer is outfitted with gold-plated, spring-post terminals that will accommodate bare speaker wire (up to 12AWG), pin connectors, and banana plugs (single only). The gold-plated terminals provide excellent audio signal transfer and resist corrosion.

In-Wall Installation:
The ISW-4 in-wall passive subwoofer is primarily intended for installation into new construction of drywall (stud wall) and solid (brick or block-work) walls, but can also be installed in existing drywall construction (see "Custom Installation" booklet for further details). The included ISW-4BB back box in-wall enclosure is required for optimal performance and operation of the ISW-4 in-wall subwoofer.

The back box enclosure installs between two 16" OC wood studs or built into the brick/block wall. In both installations, the back box will need to be covered with sheetrock (plasterboard) followed by a plaster skim.
The ISW-4 will then require a rectangular cutout measuring 10" (w) x 19" (h) x 3.75" (d) for the included mounting bracket to fit into the installed back box. The mounting bracket secures into place using the integrated "dog-ear" clamps and Philips-head screws (make sure to leave 1" of clearance around the cutout to accommodate the "dog-ear" clamps.
Once the mounting bracket is secured in place, the in-wall passive subwoofer, along with the included foam gasket, can be placed inside the mounting bracket and secured using the supplied M5 bolts.
Finally, the supplied grille mounts between the speaker baffle and frame bezel. The grille and frame bezel extends 0.25" from the wall.

Technical Specifications:


In-wall subwoofer system with external rackmount amplifier

Drive units

2 x 200mm (8 in) Paper/Kevlar® cone

Frequency range (-6dB)

17Hz and 290Hz adjustable (EQ at A)

Frequency Response

- ±3dB 21Hz - 200Hz adjustable (EQ at A)

Bass extension

-6dB at 17Hz (position A)

-6dB at 21Hz (position B)

-6dB at 24Hz (position C)

Power Handling

200W 8Ω (minimum 6.3Ω)


Height: 494mm (19.5 in)

Width: 264mm (10.4 in)

Depth: 99mm (3.9 in)

Depth with grille: 114mm (4.5 in)

Cut-out size

Height: 485mm (19.9 in)

Width: 255 (10 in)

Net weight

6.4kg (14.1lb)


Semi-matte white suitable for customizing or pre-painting

Frame/Grille Accessories

Pre-mount kit for new construction

Back Box Dimensions

Height: 1406mm (55.4 in)

Width: 345mm (13.6 in)

Depth: 86mm (3.4 in)

Box Net Weight

9.6kg (21.2lb)