PC Apex posted a review on the Razer Barracuda HP-1 3D Audio Gaming Headphones

I said the HP-1 has big cans; the reason is that there is a lot going on inside. There has to be enough room for four speakers and hopefully enough room that they can provide accurate sound separation. If you look closely you can see the front and rear speakers are canted away from each other, presumably to afford greater separation. The sub-woofer sits behind the front, rear and center speakers.

Razer Barracuda HP-1 3D Audio Gaming Headphones Review