Kappa Perfect was conceived and introduced in 1998 as a high-end line of car audio products. Infinity's claim in 1999, when Kappa Perfect Subwoofers were originally released, was that it had the longest one-way linear excursion of any subwoofer on the market. Additionally, Kappa Perfect subwoofers incorporated a somewhat higher Qts than other sealed-box woofers available at the time, which made them appropriate for use in small sealed and vented boxes. The Perfect 12d VQ represents the latest generation of "Perfect" (no modesty here) subwoofers.
Built on a proprietary four-spoke cast frame design, the dual voice coil 12d VQ weighs in at a healthy 22 lbs. The frame is well conceived and has four sets of vents below the spider that provide for substantial airflow out of the top plate voice coil/gap area.
The motor system used on the 12d VQ is pretty unique and patent pending. "VQ" stands for Variable Q. Infinity engineers, however, came up with a clever way to allow a user to personally customize and optimize the Q of his subwoofer for specific applications from small sealed boxes to larger vented or bandpass boxes and even infinite baffle applications. This is accomplished with multiple inserts marked Mid Q and Low Q. High Q (a Qts of about 0.6) is attained by using no insert at all and just having a gaping 2.5-inch hole in the back of your woofer.
Horsepower for this ride is provided by two stacked magnets, sandwiched between the milled and polished 10mm-thick front and back plates. Together the plates and magnets create the magnetic field that drives the 3.2-inch-diameter voice coil. Engineering at Infinity is pretty much state-of-the-art and the company used a good deal of computer software to design this motor system.
All of this drives a new proprietary metal cone made from a magnesium alloy Infinity calls M3D or Magnesium Metal Matrix Diaphragm. According to the literature, this material is 20 times "deader" than aluminum cones and has superior stiffness and damping compared to other materials. With a 5-inch-diameter dust cap made from the same material that reinforces the cone at its midpoint, the slightly curved M3D cone is indeed quite stiff. However, I was surprised that the outside rim wasn't turned downward, which is often seen with aluminum cones and also enhances their stiffness. I'm guessing this has to do with the bending quality of the magnesium compound.
In The LabThe same LinearX LMS analyzer with Windows software was used to make both free-air and added mass impedance measurements. Parameters shown in the Data Chart were used to produce computer simulations of two factory-recommended box volumes, one using the Mid Q insert and one using the Low Q insert. The sizes chosen from the factory selection were a 1.0-cubic-foot sealed box using the Mid Q insert and a 1.75-cubic-foot vented box using the Low Q insert and tuned to 32Hz with a 4-inch-diameter port.