DIY speaker isolation base for a wood floor

The granite slabs should be fairly large in dimension, maybe 18x18. 24x24 would be even better, more stable. If you can find one slab two inches thick, use that but only one slab. You want to reduce Center of Gravity height, not increase it. How heavy and tall are the speakers?

Use as many springs as you need to get the whole thing stable. Minimum 4. Might need more than 4. Did you calculate the spring rate of the springs based on total mass of speaker + Granite?

Thanks Geoff here is what I know.
102 lb load rated springs.
Spring constant 126.25 lbs per sq inch.
1.375" OD x 0.177" steel wire and 2.75 " length.
The slabs weigh 32 lbs and I  have four
The speakers are around 72 lbs.
I can get more when I go to town. I can't wait to try these. Thanks

It sounds to me like your springs are more suitable for a 400 LB speaker. The spring rate of the system is the spring rate of a spring x the number of springs.

Speakers are 42 inches tall.

People in little places , and theres billions of them. Wouldnt fit these in there places . I feel a strong spousal dispute.