Review: Wisdom Audio SCS Subwoofer
Most subwoofers are large, roughly cube-shaped black boxes that look about as elegant as a Vietnamese potbellied pig. The SCS — or “suitcase sub”—is Wisdom Audio’s attempt to break from the big-box subwoofer paradigm without sacrificing performance. At 37 by 7 by 22.5 inches, it’s shaped like a long suitcase. The idea is that it’ll fit in places where most subwoofers won’t: along a wall, in a tight corner or under a couch or equipment rack.
To get the SCS down to 7 inches wide, Wisdom Audio had to rely on radical design. There’s no 12- or 15-inch driver lurking inside that skinny enclosure. Instead, Wisdom uses two 5 by 7.5-inch drivers in a unique acoustical arrangement the company calls a Regenerative Transmission Line. Inside, a center wall down the middle divides the enclosure into a U shape. At one of the U shape, on the skinny wall of the subwoofer, is a metal vent. The drivers are mounted in the center wall near that vent. The fronts of the drivers fire straight out and pass through the vent; their sound waves also resonate within the long chamber. The rear wave coming from the backs of the drivers has to travel through the U-shaped passage. According to Wisdom Audio, this arrangement produces extremely high efficiency and delivers much lower bass extension than its two small drivers might normally achieve.
You can read a clear explanation of Regenerative Transmission Line theory here (PDF).
Incidentally, the Regenerative Transmission Line is in some ways the opposite of a conventional transmission line speaker. In a standard transmission line, the sound coming off the back of the driver cone is completely absorbed by a long chamber lined with absorptive material, the goal being to eliminate any interference with the sound coming off the front of the driver cone. A traditional transmission line reduces efficiency, while the Regenerative Transmission Line increases efficiency. Yet there is a price to be paid for that efficiency, as we’ll see in the Measurements section.
A 400-watt amplifier powers the dual drivers. Jacks for RCA and XLR line-level input are provided: one each for left channel, right channel and LFE. (The latter bypasses the internal crossover.) Recessed controls adjust the level and the crossover frequency (from 50 to 80 Hz); you’ll need a screwdriver to adjust these. Cute inset handles in the shape of the Wisdom Audio logo make lifting and moving the long SCS easy.