Best Isolation HRS? SRA? Zoethecus? Symposium?

No doubt here that the Vibraplane is the best isolation device on the market. That being said there are a couple of reasons for this. In order to isolate properly you must have a combination of mass and isolation. You must decouple from the surface that is vibrating in both the Horizontal and vertical planes. The Vibraplane addresses both issues. It weighs in at 150 lbs. Things at rest tend to stay at rest, ask Newton. It has a highly damped air suspension system. This isolates down to an astonishing 2.5 hz. The footers used on the Vibraplane use an ingenious slip plate technology isolating in the Horizontal Plane!!!!

There is a reason that the worlds scientific community uses Vibraplanes and a handful of other manufactures for the test equipment. IT WORKS!!! They are not direct coupled plates. Their R&D DEPENDS on results!! I've yet to hear about an electron microscope being used on a Silent Running Platform.

I've used both and while the Silent Running is very good and works well it fails in comparison to the Vibraplane. It is an audiophile tweak, where the Vibraplane is a real world industry performer.

I am a dealer for the product because it is the best and there is nothing else out there like it. We know that ADOG is a dealer for the Silent Running. Jeff, we would all benefit with a little more transparancy from your posts. We know you have an axe to grind.

Geoffkait - I can see where you are a little confused and having difficulty understanding seismic isolation.

"If what you said were actually true, the mass of the entite house (much more than 150 lb) would provide sufficient isolation."

We are talking about isolated mass here Geoff. The house like the Silent running is directly coupled to the earth, the source of the vibration. When you isolate and decouple an object properly it must have mass in order to stay put. So the earth vibrates away while the platform stays in place, partly because of the mass of the platform and partly due to the isolation. This is why they operate so well.

"Furthermore, "electron microscopes," as a class, are not the end all do-all devices you suggest; in the overall scheme of things their performance is good but not great. "

Alright, but if they are not isolated proper the performance is greatly diminished. It's not the resolution of the device I am talking about here it is increase in performance to enhance usability. Obviously the move sensitive the device the more important the isolation to obtain results. A great deal of the Vibraplanes are used in clinical, industrial and research applications where under normal consditions you will not yeild results.

Take a look at SOS's follow up response. It has a very clear indication of how the unit is designed.

Geoffkait

Nice to know that four course on vibration I took in university can be boiled down to one easy sentence Geoff. It is far more complex in study than what you have stated. It has everything to do with inertia.

"The heavy mass used in Vibraplane is employed to lower the resonant freq. of the "mass on spring" system and has nothing whatsoever to do with inertia, as you suggested. System resonant frequency is a (strict) function of the Sq. Root of spring rate over the mass."

What you talk of is a simple machine, a text book example not a real world application. What you talk of is a single degree of freedom spring and mass system. It does not particularly apply. Yes, additonal mass will lower the resonant frequency of the platform but is not the sole or most important reason for the mass. You could simply damp, clamp and change the resonant frequency with out the mass. You have completely ignored Newton and Kinetics all in one foul swoop. How about your transmission ratios, harmonic ground motion, forced periodic motion etc.?

"Thus, if vibraplane employed an even heavier mass, all things being equal, it would be an even better isolator. But not because of the reason you gave."

Beg to differ here sir. A larger mass requires larger surface areas and will not necessarily translate to better isolation. It introduces another set of issues. It is a large reason as to why it operates the way it does. Mass limits movement the isolators decouple from the source of the vibration. It is similar in operation to an inertia base under large rotating pieces of equipment, conversly though they are trying to limit the vibration transmitted into a building. Mass is key in keeping things in place and limiting both movement and transmission of vibration.

Hey Geoff with out getting into a pissing match here. We may be talking about two different things.

I am not discussing the resonant frequency here. I am discussing the use of mass to keep the platform in place. Things at rest tend to stay at rest. The higher the mass the more extenal force it takes to move the object.

If the platform were directly coupled to a stand via cones etc. the seismic churning of the earth will disturb the platform. The better the isolation the less the transmitted force. The larger mass simply keeps in place. With out the mass the transmitted forces will allow the platform to move sympathetically with the seismic vibrations.

As for the density of the materials used, VP utilizes a large billet of steel underneath to make up the 150 lbs this thing weighs. A denser material would be much more expensive and in many case more difficult to work with.

Design of industrial and institutional vibration platforms is not the simple mass-on-spring you seem to think it is. They employ over 15 PE's on staff. Check out many of the vibration and acoustic control companies around and you will find that most of these companies are made up of PHD's. Not because they want to look important but because it is a very difficult field to understand.

If it were as easy as you seem to think it is they would just employ a couple simple dense slabs of Corian separted by a couple of springs. Or every one would just use two pieces of MDF with a Thermarest mat in between.

Rest assured my textbooks are well dusted. I am PE Mechanical Engineer and work with a number of Vibration consultants on my projects on a daily basis.

Hey Geoff, I must agree. Cheers and Happy Holidays. Sorry I was not trying to knock you or anything else. Just a good lively debate. Thanks for keeping me on my toes.

Depleted uranium is a great idea, it may also have many other sonic benefits. ;-)

TBG, Kuzma uses a silcone, fluid damped isolator in their Reference Turntable to excellent effect. I've not used another fluid (apart from air) system.

"...or you could partially fill the bladders with fluids as Kworks does. Filling the center with sand would also lower the resonant frequency.

Guidocorona; Thanks for your Christmas Cheer, Ha Ha Ha, love it!