Elipson Back Box IW8

An in-wall speaker radiates as much sound backwards as it does into the room. In a hollow partition or suspended ceiling, this portion of the sound is lost in the service void, passes into the adjacent room and makes the bass dependent on the cavity behind the board. This PVC enclosure closes off the back of the Elipson Architect IN series IW8 in-wall speaker and gives it a stable support during installation.

A sealed volume behind the driver

Elipson presents the Back Box IW8 as a sealed enclosure. Without it, the IW8’s 21 cm bass driver operates in whatever space it finds behind the plasterboard. This space may be a gap of a few centimetres between two studs, a suspended ceiling plenum of several cubic metres or a cavity crowded with ducts. Bass behaviour changes from one location to another, and two identical speakers installed on either side of a television can sound different.

With the enclosure, each IW8 has the same sealed air volume, regardless of the wall. The two channels of a stereo pair, or the front speakers of a home cinema system, maintain a consistent sound. This volume does have a limitation, however: a 92 mm-deep enclosure does not extend the bass as a large open cavity sometimes would. The IW8 reaches down to 55 Hz, and a subwoofer remains the right answer for the lowest bass in cinema sound.

Less sound transmitted through the partition

The PVC shell acts as a barrier to sound emitted backwards. A supplied layer of damping material is placed inside to absorb some of the energy circulating there and improve isolation. This material is rated M1: in France, this reaction-to-fire classification denotes materials that are combustible but not flammable. This is a point to consider in a suspended ceiling carrying electrical cables, or in a shop, restaurant or meeting room, locations where the IW8 is also installed.

The enclosure does not make a partition soundproof. Vibrations transmitted through the wall or ceiling structure continue to travel. However, the enclosure eliminates the most direct path, that of the rear sound wave passing through the cavity and then the board on the opposite side. In a bedroom adjoining the living room or beneath a converted loft, this difference is noticeable.

A stable base for wall or ceiling installation

The enclosure provides a mounting surface for the speaker. It attaches to a defined support rather than just the edge of a plasterboard sheet, which is useful in ceilings, where the speaker sits horizontally and the board is often more fragile. Connection is made via a gold-plated push terminal supplied with the enclosure and a cable extension linking it to the speaker. Six screws complete the package. The assembly weighs 0.6 kg and adds almost nothing to the load supported by the wall or ceiling.

The depth to check before cutting

The enclosure’s cut-out dimensions are 219 × 321 mm, with a depth of 92 mm. The width and height remain slightly smaller than the IW8’s cut-out dimensions. Depth, however, is the constraint to check first.

A standard partition built on 48 mm tracks does not provide 92 mm of clear space. Wall lining on a wider frame, a thick partition or a suspended ceiling is better suited. The precise location must also be checked: a metal stud, joist, ventilation duct or pipe in the planned position means moving the speaker a few centimetres. Checking the cavity before cutting avoids unpleasant surprises.

Technical Specifications

Dimensions and Weight

• Cutout dimensions (W × H × D): 219 × 321 × 92 mm
• Weight: 0.6 kg

Included Accessories

• Gold-plated push terminal
• 6 screws
• Cable extension
• M1 damping material