Feedback through turntable

Good stuff Slaw. I want to get rid of the last of the rubber in my system, the inner tubes in the original Seismic platforms. I have been planning on getting some of Geoffs springs, and perhaps some of the current Townshend Seismic Pods. I find the Pods more than a little overpriced, but what else is new?!

I too had a VPI HW-19, and considered it about as good as a suspended-subchassis design could go. But you're right---that MDF platform was it's weakness. I never heard the later acrylic version, having moved on to the Townshend Rock table, which certainly doesn't have THAT problem!

Todd, I learned of roller bearings from audiophile recording engineer Barry Diament, a leading proponent of them (using them under every piece of his gear, even his Maggie MG 3.7’s!). He had his own "cups" machined locally years ago, and on his website blog details their design. Contributors on his site have offered their homemade versions of the isolators, usually of very low cost with a corresponding reduction in effectiveness (due to the softness of the bearing cups, often of plastic, wood, or cheap pot metal).

There have been a few professional/commercial companies making roller bearings over the years, most famously Symposium Acoustics with their Roller Block, it’s cups machined from aluminum. The Jr. model is the best deal, a trio of 1-7/8" double-cups with a half inch ball bearing between the upper and lower cup, priced at $180/set. The major difference between Diaments design and the Symposium Jr. is in the Jr’s use of top and bottom cups, in contrast to Diaments preference for a single cup, with the ball bearing itself in direct contact with the bottom of the component.

There is a small company in Canada making two versions of a roller bearing, Ingress Audio Engineering. Their Model 2 is identical to the Symposium Jr, just without the Jr’s black anodized finish, priced at $120 for a set of three double-cups with ball bearings. They also offer their Model 3, made to Diaments specs, a single 1-7/8" Alcoa 7075 aluminum cup with a very large 2" diameter "bowl" machined into it. The gentler slope of the bowl resulting from it’s larger size results in the bearing having a lower resonant frequency, therefore possessing greater isolation properties. The cups are also polished to a smoother finish than are the Model 2. The Model 3 sells for $175 for a set of three cups and ball bearings. The Ingress email is [email protected], phone number (519)981-2031.

rotaries is absolutely correct; cones and spikes are not isolators, they are couplers---at least, in the very low frequencies needed for turntable isolation. The idea that cones and spikes provide wideband isolation seems to be a deeply-entrenched misconception amongst hi-fi fanatics, one that persists in spite of overwhelming proof to the contrary. Cones and spikes DO provide some isolation above around 10Hz, but below that frequency couple, not decouple, two physical bodies (such as a table and the shelf/platform it is sitting upon).

The Newport and MinusK isolation tables are state-of-the-art (providing deep isolation to at least 2Hz), but rather expensive (over $2000). A cheaper, and admittedly less effective, method of achieving isolation is with a combination of lateral and vertical decouplers---roller bearings for the former, air springs (or metal ones) for the latter. A mid-priced solution is the Townshend Audio Seismic products, available as single pods, platforms, and speaker stands. Audiogon member Folkfreak employs the Townshend Seismic products in his excellent system.