Ingress Audio Engineering

Bluestone is quarried in western New Jersey, Pennsylvania and eastern New York.[15] It is also quarried in the Canadian Appalachians near Deer Lake in Western Newfoundland.[16]The Pennsylvania Bluestone Association has 105 members, the vast majority of them quarriers.[17] Bluestone from Pennsylvania and New York is sandstone defined as feldspathicgreywacke. The sand-sized grains from which bluestone is constituted were deposited in the Catskill Delta during the Middle to Upper Devonian Period of the Paleozoic Era, approximately 370 to 345 million years ago. The Catskill Delta was created from runoff from the Acadian Mountains ("Ancestral Appalachians").[18] This delta ran in a narrow band from southwest to northeast and today provides the bluestone quarried from the Catskill Mountains and Northeast Pennsylvania. The term "bluestone" is derived from a deep-blue-colored sandstone first found in Ulster County, New York.[citation needed] It can, however, appear in many other hues, mostly shades of grays and browns. Bluestone quarrying is of particular value to the economy of Susquehanna County, Pennsylvania. The Starrucca Viaduct, finished in 1848, is an example of Pennsylvania bluestone as a building material.[17]

The other, lesser known, type of American 'bluestone' is a blue-tinted limestone abundant in the Shenandoah Valley of Virginia. It is a limestone formed during the Ordovician Period approximately 450 to 500 million years ago, at the bottom of a relatively shallow ocean that covered what is today Rockingham County, Virginia. The limestone that accumulated there was darker in color than most other limestone deposits because it was in deeper waters exposed to less light. The darker blue color resulted in limestone from this region being dubbed bluestone and with two sequences measuring about 10,000 ft thick, it gives the area one of the largest limestone deposits in the world.[19] The stone eventually fades from a deep blue to a light grey after prolonged exposure to sun and rain. Given the abundance of the stone in the Rockingham County area, the first settlers used it as foundations and chimneys for their houses. When James Madison University was built, the local bluestone was used to construct the buildings because of its high quality and cultural heritage.[20]

@geoffkait, by "secrets" I meant how your springs differ from the commonly-available, off-the-shelf springs. I doubt you make them yourself, but you do cryogenetically freeze them. Anything else you care to divulge? ;-) Not that I expect you to; I wouldn’t!

In one of his video (viewable on You Tube), Max Townshend demonstrates the difference between his Seismic Pod and a bare spring of the same rate. Very interesting.

No offence taken, perhaps because I don't know what you meant ;-) .

Say, are ya gonna tell us why the roller bearing is no good for isolating a turntable? I haven't come up with anything better than the spinning moving mass of the platter pulling the ball bearings in the direction it is spinning (clockwise).

@uberwaltz and @elizabeth, the idea I came up with when I first saw Barry Diament's big Maggies on roller bearings, but transferred to my carpeted room and the pair of Tympani IVa I thought I would be able to shoehorn into that room (alas, that was not possible :-( ) was this:

Make a base plate out of Maple/Baltic Birch plywood/etc., and install three spikes in it to raise it off the carpet enough to make it stable (three is inherently stable, four a chore), and level it. Mount the Maggie feet/stand/base plate onto a similar piece of wood (may as well make it the same size as the one on the floor), and place the wood-mounted Maggie on top of the base plate/bottom piece of wood, with a trio of roller bearings between the two boards.

The same can be done with Geoff's springs, or even with both, using another board. Wood is cheap!

In looking at the diagram blowup of the GAIA on the IsoAcoustic website, I came to the conclusion that whatever isolation they are providing must be by way of some sort of rubber. They say it's not Sorbothane, but may it be Navcom? That stuff is still being made, and is used in firearms and other fields as mechanical dampers. I doubt it's the EAR rubber, but who knows?

I hope it's not, as the isolation properties of rubber doesn't extend very low in frequency, which is what we want. The lower the better. But remember when everyone ditched the springs in their VPI HW-19 tables for the SIMS Silencer Navcom pucks? Not all springs are created equal, and I don't think Geoff is going to share his secrets!

If I had the dough, I'd have a Herzan or Minus K under everything. Audiogoner folkfreak has his table on a Herzan (he had me over for a listen), and it's a thing of beauty! 

@uberwaltz, Barry Diament wrote that the roller bearings made more difference under his Maggie 20.7’s than under his electronics. But then he uses all solid state stuff, and records in digital. He uses the 20.7’s as monitors! You can see them on his website. He bolted the stock Maggie feet onto a 2’ square piece of plywood, then put a trio of bearings under the plywood. What I wonder is if he puts the bearing cups right on his carpeted floor, or on top of something else.

I have my Eminent Technology LFT-8b’s bolted onto Sound Anchor stands, which are a tripod design (inherently more stable than four feet, as found on loudspeaker outriggers). The SA’s come with spikes, but a set of roller bearings, GAIA’s, or Townshend Audio Seismic Pods can easily be substituted, which is what I intend to do. The Pods would run about $600, the GAIA II’s (good up to 120 lbs.) also $600 (they come in packs of four, so I would have two left for some other application), the Ingress V.2 only $140 if used single-cup style. The V.2 plus a set of Geoff’s springs would make a great budget isolation system. @geoffkait, how do you recommend your springs be partnered with roller bearings? I may just use my Symposium Jr’s, double cup style, therefore not having to be concerned about the LFT’s rolling off the bearings!

@redlenses03, if you want pneumatic isolation, and don’t mind spending a little money and time, you can keep your eyes open for the old Townshend Audio Seismic Sink platforms that were made in the 90’s-00’s. There were a few different versions, but they all shared the same basic design: an inner tube inside a top and bottom steel plate structure. The inner tube is inflated just enough to keep the top and bottom plates from touching; the lower the P.S.I., the lower the resonant frequency and the greater the isolation. A set of roller bearing on top of a Seismic Sink provides isolation is all planes.

Or, you can get the current Townshend Audio Seismic pods, but they’re around $100 each. Sets of Pods for a complete system can add up to quite a bit of money. But then two sets of the IsoAcoustic Gaia I’’s---enough for a pair of heavy loudspeakers---will cost you $1200, more than two sets of the Pods. The GAIA II is $600 for two sets, the GAIA III $400. Not too bad if you have light (under 70 lbs.) speakers.

I's still waiting for the same responses I got when I brought up Ingress Audio on another thread some time ago. A couple of posters claimed whatever sat on the bearings would roll right off and couldn't believe it would work.

"Pop quiz

Can anyone think of a reason roller bearings might not be a good idea under a turntable?"

So true @uberwaltz. For not much $, one can substitute harder, smoother tungsten carbide ball bearings for the stock steel balls. Symposium charges a small fortune for them, but they are available from ball bearing vendors for far cheaper.

By the way, whether or not anyone thinks the original Ingress was a "knock-off" of the Symposium Roller Block Jr., Symposium was in 1997 granted a patent for the "double-stack" design used in both bearings.

"Pop quiz 

Can anyone think of a reason roller bearings might not be a good idea under a turntable?"