mpfrank

The best foam surrounds I have used come from Audidogs https://tinyurl.com/yjbzdcl4 They have the proper internal slant to match the woofer cone. Many others are flat and don't fit well.

Hi Doug. I still have mine and would be happy to sell it. As has been posted, the effect is subtle, as most music doesn't have much sound below the frequency response of the Allison speakers.

Hi Gitendra. A year after your post, I do still have it if you are still interested.

I actually have one of these that I bought used on Ebay. I have used it with Allison 115 speakers - 8"woofer - and I couldn't tell any difference. Could be the speakers, could be the room, could be the electronic subwoofer itself, could be the music, could be my ears. Anyway, I'd be happy to sell it if anyone's interested.