< p> The 600f Series offers a wide range of DD AUDIO’s most popular Power Tuned Subwoofers designed for remarkable power handling, to be a serious bassheads daily driver.< br> < br> < br> REVISION ‘F’< br> Previous revisions of the 600, 700 and 800 Series subwoofers made them bigger and better and in this latest “f” revision they receive precision engineered, thermal cooling enhancements of major significance along with some design work that is literally cutting edge.< br> < br> THERMAL TRANSFER< br> The “f” revision subwoofers were specially engineered to deliver improved thermal transfer. The Dual Stage Aluminum Heat Sink works to conduct heat away from soft components, into open chambers where the Free Flow Cooling System is pushing through cooler inducted air in order to expel this heat.< br> < br> MORE XMAX< br> As the top plate thickness was increased the voice coil winding was lengthend to keep more coil wire in the gap. More coil wire surrounded by both motor steel and billet aluminum pulls more heat away from the coil in all conditions, optimizing electrical efficiency in long term usage.< br> < br> TALLER SURROUNDS< br> Increased Xmax and excursion required enhancements to the moving system, therefore taller surrounds have been tooled and the spider refined to fully optimize the new motor design. The taller surrounds are double stitched to fiberglass loaded non-pressed cones. Double layer, multiple spiders continue the DD tradition of long term durability.< /p>