Who make's em? All I seem to be able to find are 4 ohm versions, save for those good folks at Eden who had the heart to make an 8 ohm 18" --anyone else? I know Yamaha makes 18" PA units (Not sure about 8 ohms though), but I seem to remember conflicting reports of using a PA sub for soley bass purposes. Is my memory shot on that one, or what? Anyway, I was wondering if any of you knew. I'd really like to add an 18" to my rig, and an 8 ohm is what I need to not blow the amp's load (already have an 8 ohm 410). Any info/suggestions/advice?