A definite sonic improvement in tightening up the bass. 1. Start with 4 aluminum cones. I used some old Mod Squad Tip Toes. 2. 16x16 slab of granite. 3. 1/8 cork. 4. 1/2 inch neoprene rubber. 5. 1/8 cork. 6. Top with another 16x16 slab of granite. 7. Enclosed with a wood cradle to hide the mechanism. The granite is from scraps from a shop and was cheap. The added 1/4 inch of neoprene to 1/2 inch thickness did help. Let me hear your thoughts.