In a cone driver distortion increases rapidly as the excursion of the cone (travel in and out) increases. Drivers made for subwoofer use generally have a large range of excursion, but it's obvious by looking at a busy subwoofer that the full range is easily used up. The more cone area you have the less excursion is necessary, and therefore the lower the distortion. Large drivers, 12" 15" 18" (and even 30") are most suitable. Multiple drivers also help, and a pair of 10" (roughly equal to one 12") is sometimes used.
The custom design subwoofer systems of my three front channels include three 15" and three 12" cone drivers. Even so, they have less area than my Maggies.
The custom design subwoofer systems of my three front channels include three 15" and three 12" cone drivers. Even so, they have less area than my Maggies.