I wouldn't say L7's are 'crap', but I would say they are designed for a goal that does not align with my needs. The square cone design lends itself to the idea of quantity over quality.
Consider a few things. One, you dont get cone area for free. Kicker advertises that you get the cone area comparable to a 15" round sub, using a 12" square cone. Sounds fantastic, right? The problem is, that 12" sub also requires the enclosure size comparable to a 15" round sub. To be frank, I dont care what the diameter of my sub is nearly so much as how much room it (it's enclosure) takes up in my vehicle. Once you realize this, you begin to see the less-than-honest marketing that goes into these square drivers.
Second thing to consider, there is a reason speakers have traditionally used round cone, their strength to weight ratio is inherently better. A round cone distributes the stress on the cone evenly throughout its surface, a square cone does not. To simplify the physics involved, look at it this way: the corners of a square sub are further from the center of the cone, where the force/stress from the t-joint originates, than are the edges of the cones along the 'flats'. That difference in distance means the corners see more stress than does the area of the cone along the flats. This means as the cone moves, its shape inherently creates a situation in which the cone is trying to warp. Round cones do not have this problem. Its easy to see this is true, just look at the Kicker square cone design, it has stiffening ribs running out to each corner from the center. Problem solved, right? Not exactly, these stiffening ribs mean additional cone material that does not add to the surface area, it merely works at keeping the cone rigid. That added material means more weight. While moving mass is less important on subs than it is with tweeters, its still somewhat of a factor, and again goes back to the idea of quantity over quality.
The only advantage I see to square cones is more efficient use of your baffle board profile. In other words, you can run an array of square cones, butted up against each other, with virtually no dead space. With round cones, even mounted right against each other, there will always be some of the baffle board that does not have cone covering it. This really is only important in installs where an array of subs is being used, or if space is so tight that you do have the enclosure volume to accommodate a 15" sub, but baffle board space of 12" or less. This IS an advantage over round subs, but the installs that require this advantage are few and far between.
Kicker is not the first company to utilize a square cone, no matter what they wish you to believe. They are simply the first company to successfully market them.
