Hey Litefoot, I heard you have a set of Hartley's! Me too. I acquired a bunch from the daughter of a long audiophile/apple farmer. They are excellent sounding speakers and rather rare. I think the poly cone idea is a good one. I have a CM IV with the 24" woofer, and maybe a Holton or a JR with the 18". I also got two other enclosures with MSGs. cheers.