ESX QXE8D2 - 20cm subwoofer

QUANTUM QXE  Subwoofers impress with their very compact design. The QXE6D2
subwoofer appears almost delicate, but with its die-cast aluminum basket, dual magnets with 2 x 40 oz. and stitched surround, it signals: "Caution, it can get very loud!"
The two larger subs have powerful 2 x 63 oz. dual magnets and, just like the QXE6D2, a pole core bore and a vented T-plate for optimal cooling.
The QXE6D2 uses a large 2" (50 mm) voice coil with an RMS power handling of 250 watts, while the QXE8D2 and the brand new QXE10D2 model even use a 2.5" (64 mm) voice coil with a power handling of 400 and 600 watts RMS, respectively.
Extremely long-wound voice coils with a winding height of 30 or 36 mm allow the woofers a linear stroke of +/- 10 mm. All three models have a dual voice coil with 2+2 Ω each. This allows impedances of 1x4 Ω or even 1x1 Ω to be configured.
This makes it easy to operate several subwoofers in series on a single amplifier.