We would first like to point out a few items on the OP’s brass cone examples and will follow up with a functionally proven theorem that has taken the first steps to qualify as a science.
Cones (spikes) - the Shape is rarely talked about. Using the image from the OP exposes so many fallacies that the product would never work.
1 Take the machined knurled rings with uneven edges. These establish notches in the body that create rough surfaces and shear waves. The energy has an unsymmetrical travel pathway that makes a lot of noise and distortion. With an uneven medium, the energy flows back into the speaker's chassis.
Reflected sound is like light reflection. It is ten times more evident on rough surfaces. The nuts on this cone design produce a lot of noise.
2 If you take a horizontal view and discover an exposed thread, the system becomes dysfunctional by establishing a separation in the mass and shape of the material. Using a separate nut for leveling the speaker breaks the transition of resonance flow. This designer needs to learn how a cone works before selling fancy-looking parts. Most spikes manufactured have zero capability of function other than raising speakers off the flooring.
3 The disc receptor has ninety-degree angles. Ninety-degree angles add noise and distortion—the same with wall, ceiling, and flooring angles. Ninety-degree angles limit performance in speakers, inside and outside of chassis, pucks, springs, etc. They are not beneficial for energy flow and sound.
The examples shown do not work, so you need to upgrade the designs before they qualify for analysis purposes.
Adding rubber or any material between the device and the floor other than an engineered coupling disc adds to the soup sandwich attempting to correct something doomed from the outset.
Impurities in the material also generate shear energy. There are hundreds of types of brass. Cheap brass means minimal attention to chemical manufacture and less performance. Chemistry is essential to the functionality of any cone shape.
Robert Maicks
Vibration Management Specialist
Tom DeVuono
Research & Product Development