Barry Diament bolted each of his Maggie 3.7’s onto the middle of a 2’ x 2’ plank of plywood, and placed a trio of roller bearings under the plank in an equilateral triangle. Symposium Acoustics sells their Roller Block Jr. in sets of three, each of the RB’s having two 1-7/8" blocks of black-anodized aluminum into each of which is carved a "bowl". A single ball bearing separates the two blocks, one blocks bowl facing up, the other down. Barry prefers to use only one bowl, with the ball in it being in direct contact with whatever is placed on top of the bearing. Because the ball would depress into the plywood base from the weight of the speaker, Barry put a square of hard tile in three locations on the bottom of the base, one for each ball to be in contact with. He does the same with the bearings under his electronics, but puts the tile directly on the bottom of each components casework. He argues that a ball bearing moving in a single cup has a lower resonant frequency than does the ball in two cups, thereby providing isolation to a lower frequency.
The Symposium Acoustics Roller Block is nicely machined out of Alcoa aluminum, the ball bearing free to move in the bottom of each bowl. When receiving mechanical vibration, the ball "wants" to move horizontally, but since the surface it is on (the bowl in the block) is not flat, in order to move it must "climb" up the side of the bowl. That movement is microscopic, and is what provides isolation; the object under the roller bearing is vibrating, and those vibrations try to move wherever they are most easily absorbed and transferred on. The ball bearings, rather than transmitting vibration through them and into whatever sits upon them (which is what spikes and cones do), instead moves microscopically, using up the energy it receives in attempting to climb up the side of the bowl. The larger the bowl, the lower the bearings resonant frequency, and the lower the frequency to which will the bearing provide isolation.
I don’t know the diameter of the bowl in the RB Jr., but it is not as large as it could be, or as Diament recommends. There is a machinist in Canada making his own version of a roller bearing, in fact two of them. The original consists of a pair of 1-1/2" aluminum blocks with bowls, pretty much an exact copy of the Symposium RB, but without the black-anodizing. Due to demand from myself and others, he has created a second version, one with a larger diameter, shallower bowl in a single block, the shallower bowl thereby, as I said, providing isolation to a lower frequency. This block is machined from a harder grade of aluminum, and polished to a smoother surface texture. The company is named Ingress Engineering, and it has a website with all the details and ordering information. The highest performance roller bearing around, and cheaper than the Symposium Roller Block!
The roller bearing provides isolation in all planes save vertical, hence the need for another form of isolation in addition to it, such as an air bearing or a spring. The Townshend Seismic Pod appears to provide vertical isolation, so may be the only device necessary. Gotta get me some!