DIY speaker isolation base for a wood floor

6) The one where you get creative and figure out a way to have the springs and sorbothane between the two slabs at the same time ... or maybe the springs and a stack of lightly compressed cork. That way you get isolation and dampening.


Which springs are you getting? If you have them at the bottom, you need the right springs for 125lbs (spring and two slabs). The resonant frequency of the spring is a factor of spring constant and loading.

Oops I don't know. I went by today and they had 6 so I had them order 2 more. I should have taken them home with me. I can call Friday and find out though. This is fine line technical. Thanks.

Should I get conical springs?

If you have large diameter springs and do not overly compress them, you don't need conical spings. Conical springs have better stability the you can make one layer sit within another, but you shouldn't be compressing them that much. It is a bit harder to calculate the operating point for a conical spring.

My original Nimbus Sub Hertz Platform used a SINGLE geometrically correct airspring. It was a convoluted Goodyear rubber airspring that expanded to a height of about six inches with 35 LB of pressure. It was three inches in diameter. The advantage of a single airspring is that you get much lower resonant frequency for the system. That’s how I got below 1.0 Hertz in some directions. The Nimbus was also designed to achieve isolation in six directions.

The problem for a single single in case it’s not obvious is that it is very unstable for any load above about five LB. So I used a clever system of horizontal springs located at the bottom of the airspring to provide the necessary lateral support so that components up to 40 pounds could be isolated with stability. Otherwise the airspring would just flop over. I also incorporated a large auxiliary air canister that was connected to the airspring with a brass air fitting. The top plate of the Nimbus was connected via four 3’ long steel rods to a sub-plate located below the aux air canister. 60 LB of dead weigh were placed on the sub plate to lower the center of gravity, required along with the lateral spring system to achieve stability under load.

The Nimbus was also tricked out so that the top bolt holding the airspring to the top plate was adjustable so that the top plate could be made perfectly level after setup. The “perfect geometry” of the airspring is defined as very small surface area on top and very large internal volume. Hence the large air canister. Voila! 🤗