All high excursion subs with a butyl rubber surround will have a problem with the surround deforming at the excursion limits. If you compare the ED sub on YouTube to the picture on the ED site, you will see that they changed from a tall, rubber surround to a flatter, wider, foam surround. It was a trade-off. The surround won't deform but they sacrifice cone area. Everything in subwoofer design is a tradeoff.
I run a pair of 15" TC-3000's in my home theater. They have a tall, rubber surround and more linear excursion than the ED driver being discussed. In this YouTube video , you can see that this surround also deforms at the excursion limits. As you can see, it deforms equally all around. That's good. That means the surround is still keeping the cone centered. I've taken my sub to these limits as well. In a free-air test like I linked to, the sub has very little mechanical noise. I have no problems with a surround doing that as long as it is even and quiet about it. I'd much rather have additional cone area.
The real downside to the rubber vs. foam was the extra ~200g of mass. The thing was a low end beast but don't ask it to play much over 60~80Hz which meant it wouldn't work too well in a car. The deformation, as you noted, did nothing to hamper the speaker, most people just don't realize that's a normal thing when you're pushing something that far.
I'm prepping some blown TC-2000 top assemblies for reconing and the surround is extremely heavy (for a surround). Same with a recone I'm doing of an Eclipse sub. The 12" recone kit with the rubber surround is as heavy as an 18" recone kit with a foam surround. But I have enough motor strength and amp power to overcome the extra weight.
Plus more moving mass is fun in the right application
That driver in an HT box is pretty much awesome. We just can't afford to have two variations of those things currently stocked...maybe one day, but the foam surround is still a beast in an HT app as well.
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