Vibration Control for Lightweight Tube Components


I'm looking for suggestions to isolate a lightweight tube preamp from vibration and resonance. Not acoustic vibration, but physical vibration from the stereo rack. When I touch the shelf the preamp sits upon, the sound can be heard thru the speakers.

I am using a heavy furniture grade stereo rack for my components, all using Herbie's Tenderfeet for isolation, including my TT. The preamp only weighs 7 lbs. and has Herbie's tube dampers applied, but needs to be decoupled from the heavy wood shelf. I've tried the Tenderfeet and Vibrapods under the preamp, but neither provided isolation from vibration.

So, what are owners of lightweight tube preamps and amps using for vibration control? (there is a limited amount of space between the shelves).
128x128lowrider57
Al wrote,

"Lowrider, I’d suggest trying Mapleshade Isoblock 1’s, or the lower priced generic equivalent that I think may be findable at Home Depot or elsewhere. Assuming that their 1.75 inch height can be accommodated. I say this even though the description recommends that they be used only in conjunction with isolation platforms."

Ah, the age old conundrum, should I isolate or should I couple?

;-)
The cheapest way to get great isolation: two Baltic Birch plywood shelves with a barely inflated bicycle tire between them, with a trio of roller bearings between the pre-amp and the top BB shelf (this design courtesy of Barry Diament). If you have the dough, a Minus K platform ($2500 or so). Alternative: a trio of the Townshend Audio Seismic Pods (about $750, I believe)
"The cheapest way to get great isolation: two Baltic Birch plywood shelves with a barely inflated bicycle tire between them, with a trio of roller bearings between the pre-amp and the top BB shelf (this design courtesy of Barry Diament). If you have the dough, a Minus K platform ($2500 or so). Alternative: a trio of the Townshend Audio Seismic Pods (about $750, I believe)"

i can do it better and cheaper. The issue with the bicycle inner tube approach is that the surface area of the air bladder/spring is too large relative to the volume. To maximize isolation effectiveness the surface area of the air spring or bladder must be minimized. Besides, a barely inflated inner tube doesn’t provide sufficient pressure/spring rate to actually do anything. That’s kind of the whole point of mass on a spring isolation.

Thanks everybody for the input so far, but I have a theory...
both preamps have exhibited the same problem; both have an exposed tube design on top of the unit.
The preamp sits on a shelf enclosed in thick wood (pine) open in front and back. If the shelf is tapped on, it may create resonances surrounding the unit thru the sides and shelf above it. These resonances may be picked up by the exposed tubes which are in close proximity. (The shelf is 10" high with enough room for air to circulate).
That would explain why a 30 lb. Rogue preamp picked up noise from tapping on the shelf. Does this theory make sense to anybody?

@geoffkait
 Ok thanks, I understand the concept of "mass on spring" now. In addition to the Mapleshade Isoblock 1, following this concept, there are Bright Star IsoNodes for isolation...

http://www.audioadvisor.com/prodinfo.asp?number=BSISO&variation=L4
IYO, would these be a good size and provide the right amount of spring rate?

@almarg ,
Al, as a test I used a wad of bubble-wrap as a cushion under the IC's and was unsuccessful. 

Lowrider,

according to the blurb for the IsoNodes they are vibration control devices as opposed to real (mass on spring) isolation devices. They are not springs nor do they act like springs, in other words. They are apparently some sort of viscoelastic damper. No offense intended to IsoNodes.

"IsoNode Large Isolation Feet are 1.25" wide and .75" tall and are great for integrated amps, preamps, DVD players, CD players, and more. Use them by themselves or with other isolation accessories such as platforms. Adhesive backing is included for easy attachment and positioning on your components."