Dayton Audio 12" Ultimax subwoofer kit

The Dayton Audio 12-inch Ultimax subwoofer kit is aimed at the builder who wants a serious low-frequency driver without having to specify every part of the project from scratch. The Ultimax line is Dayton Audio's long-excursion subwoofer family, designed around a heavy motor and a suspension that stays linear well beyond the point where a general-purpose woofer begins to compress.

A twelve-inch cone is the size most home subwoofer projects settle on, and for good reason. It has roughly forty per cent more radiating area than a ten, so it reaches a given output level with less excursion and therefore less distortion, yet it still fits a cabinet that can be placed beside furniture rather than instead of it. Compared with a fifteen it asks for a considerably smaller box and stays cleaner through the upper bass, which matters if the subwoofer is crossed over above 80 Hz.

Long-excursion drivers of this type are unusually sensitive to enclosure choice, because their compliance and moving mass are deliberately set for small boxes. A sealed cabinet gives the gentlest roll-off and the best transient behaviour, and suits rooms where reinforcement below the tuning point can be relied on. A vented alignment trades that for several decibels of extra output near the tuning frequency, at the cost of a steeper cut-off below it and much less protection against very low frequency content.

Whichever route is chosen, simulate the alignment from the published Thiele-Small parameters before cutting any panels, seal the driver to the baffle properly, and brace the cabinet: at these excursions a panel that flexes will be heard.