Wood blocks underneath components?? snake oil?

Rotarius:

Why not try to minimize the problem by first isolating the chassis from the rack and then dampen the chassis?

Because isolating will 1) increase the number of vibrational modes in the system since each component will be vibrating at its own frequency 2) Do nothing to reduce the amplitude of those vibrations - you need to raise the resonant frequency to do that. Then you dissipate the HF / low amplitude resonances by, perhaps and composite shelf of differing materials laminated together.

IMHO you need to DRAIN the component's vibrations and rack's vibrations into a suitable shelf material (there are other threads at A-gon on suitable shelves which do this). Sorbothane isn't going to do this, rigid material will.

cdc,
1) Even if you rigidly couple all components in your rack, each component will still have a different resonant frequency due to differing mass, volume, materials which result in different natural frequencies. This based on scientific fact. A spring or an elastomer is typically used to reduce the amplitude of the wave that produces vibration in a medium btw. Rubber is used to isolate a jet engine from an aircraft frame. For the record, unless the component is bolted down to the shelf, it is not a "rigidly coupled" system to which you can apply the formulae from rigid body mechanics. A component on brass cones can very easily be disturbed compared to the rack it sits on.
2) Please read my earlier post on this subject. The only way to reduce magnitude of the vibrational force transferred from the shelf to the component is to have an isolator and damper in between. Increasing the mass of the platform helps in theory but for practical reasons can't be the only way to dissipate vibration. If the offending force can make it's way through concrete slabs of your floor, you will need a lot of mass to dissipate it if you do not want to use a real "isolator". BTW, what makes you so sure that by rigid coupling everything you have raised the natural frequency of all the components beyond the audible range? Glass ringing/resonance occurs at higher frequencies, why are glass shelves frowned upon by audiophiles in that case? Lastly, anyone in the isolation business ought to have measuring devices (that are readily available) and back up their claims with numbers. How many of them do?

Cdc, FWIW, You are probably correct. I doubt that we will agree on anything when it comes to this subject.

But, FWIW, I would pose a question which no one has ever answered for me. Assuming, for the sake of discussion, that you are correct regarding the "drain" theory, and assuming that you have a component, or part with-in which is more likely because each component part will have its own individual resonance point, which resonates at, say 5000hz, exactly what amplitude must this resonance reach before it actually affects the SOUND of the component.

IMHO, it's only an esoteric theory unless one can establish that it not only actually exists in the minds of our scientists, but as pratical matter for audiophiles that advertised methods actually work to solve a real problem experienced in audio components and their use in the home.

It seems to me that if we have a problem based on something as well explored by the scientific community as resonances/vibrations that there must also exist a method of quantifying the amplitudes necessary to cause a deterioration in sound quality. IMHO this is not an area where 'subjective' observations have much meaning (to me at least).

IMHO, the 'drain theory' is on the same level as someone saying that we aught to provide for compensation in out TT set ups for the effect of the moon. I mean it (the moon) sure effects our invironment - no arguement can be made there - so it must effect our TT's operation which are infinitely suseptible to all sorts of things, and we should be able to make adjustments to compensate, shouldn't we?

FWIW, I get a real kick out of someone saying that a 'component' has a resonance point which can be moved by choice of isolation/coupling. As I suggested above, if a component has 100 parts, it has one hundred resonances within, one for each uncommon part. Do these somehow combine to make just one resonance for the whole component? Perhaps I'm just speaking from ignorance - I guess I'll have to take some physics course so I can understand this

As indicated before, I think the drain theory offers more commercial opportunities than it actually solves real world problems. IHMO of course.

Excellent point Newbee, I will begin design on a moon shield immediately :>)