Recommend 8" Driver for Aperiodic Cabinet

[konut]

I have 2 cabinets that measure 14 1/2"D X 11" W X 20" H of triple constrained layer construction with 2 ScanSpeak SSV aperiodic vents. Presently Visaton B200 full range drivers reside in them. I would like to turn them into subs. My current main speakers use a passive line level high pass filter at 70hz, 24db per octave. I use a12" powered sub with these. What I'm looking to do is make stereo subs from 70hz down to ? and then low pass in the powered sub. Are there any 8" drivers that naturally low pass at 70hz suitable for these cabinets?

[Taterworks]

I think you just made a transducer designer somewhere have a heart attack. It's difficult enough to get drivers to roll off smoothly and naturally in the midband.

I think you need to come up with some passive crossover arrangement, or an active crossover and suitable amplification for the subs. In fact, you might as well scrap altogether the idea of reusing these existing cabinets with other drivers -- put Visaton B200s in them and sell them if you can. Design a cabinet that's properly suited to the drivers you want to use.

[konut]

If not a heart attack, maybe a good laugh. The natural roll off would have been the ideal cheapo solution. Next cheapest option would be a pair of 70hz 24db per octave line level passives before a stereo amp. If the natural roll off is out of the question then a nice, flat 8"er, with no strange out of band resonances, suitable for the aperiodic box. It wouldn't have to extend to subterranean levels, I've got the powered sub for that. I already had the nice enclosures so I just thought I'd put the question out there.

[technofreak]

Maybe these? They use the same frame as B200, so it would be easy swapping. And I quess they would work nicely in those boxes.

[konut]

Those would work but, looking at the freq. response curve on the Visaton site, they have a low sensitivity at the frequencies I would be using them at. Any other recommendations?