Vibration Control for Lightweight Tube Components

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?

I think what you are referring to is known as a "sympathetic vibration" effect.
I suppose the possibility can’t be completely ruled out, but it seems to me to be unlikely. In part because the tube types in the two preamps are different, and also in part because you’ve been using tube dampers. Also, I’ve had many different tube components on pine shelving over the years (what is referred to as 1 inch pine, which is actually about 3/4 inches thick), without a lot of space around the components, and without ever having that kind of problem. Although I don’t think the tubes in any of those components were quite as exposed as the ones in your two preamps. (I have used anti-vibration products under the feet of many of those components, btw. The particular products I’ve used are no longer made, however).

I have no particular knowledge of or thoughts about the IsoNode feet.

Best regards,
-- Al

Thanks for stating your experiences, Al. And as far as my thoughts on "sympathetic vibration" go, you're right about the different tube types and the use of tube dampers. The Rogue used 4 12AU7's which are low noise and rarely microphonic.

In both cases, with the Rogue and the Atma-Sphere, I've removed the stock feet. As mentioned earlier, the only solution to remove the noise with the Rogue was to isolate beneath the unit and mass load on top.

 I wonder if the new lightweight preamp should sit on some MDF with isolation footers between the pine and the MDF.

I run my ModWright LS 36.5 on 3 Daedalus DiD,s isolation devices on a bamboo cutting board from Ikea "Lamplig" on 4 RTOM Moongel dampening gels on my rack. The cutting board and gel pads are very affordable and made a difference but the DiD's on their own are incredible. I wasn't having any issues with noise but per Dan Wright's recommendation tried the DiDs and am floored how they have elevated the sound of my 36.5 to another level. The 36.5 is great on its own but with the DiDs, piano, cymbals, brushes on a snare are much cleaner and have longer decay: the 36.5 breathes more... more open.

Try the IKEA Lamplig with the Moongels first. They're cheap. The cutting board has a grove on one side so face that side down and place four Moongels to the inside edge of the grove. This tweak with shipping is less than $40. The DiD's are $160 ea. and worth it. I only have one set but will be getting another set for my CD player. I tried them under my CD player and they work there as well but the improvement was much greater on my tube preamp. I'm using Herbie Tube Dampers so I was a little surprised how drastic the DiDs improved things. 

If you live close to a Guitar Center or any drum shop you can get Moongels there. Us drummers use Moongel on cymbals and heads to control resonances. Try just the Moongels under the feet of your pre first to see if that alone works. A package of six gels is $7.

Lowrider57 wrote,

"@geoffkait, I thought they might be "spongy" like the 1/2 tennis ball concept."

-- tennis balls or 1/2 tennis balls don’t have the right spring action to act like a real spring either. You actually need to match the spring rate of the springs to the mass of the component. I’m not saying tennis balls or bicycle inner tubes or gooey type devices won’t do anything, I’m just saying they’re just not as effective as real isolation devices, like my springs. While gooey or rubbery type materials like these or say Sorbothane might seem like good materials, even perfect materials for audio applications, they seem like such a good idea, right? But they are a pig in a poke. You will do much better with mass on spring plus very hard materials to support the iso device and to support the component on the iso stand, generally speaking. It has been 20 years since the Vibraplane iso stand blew into town. That changed everything.

"The ad goes on to state...
IsoNode feet are specially engineered from a unique polymer that rejects a wide range of vibration trying to enter from underneath the component. The highly compliant IsoNode acts as both a liquid and a solid for superior vibration control. Vibration and resonance that could interfere with the performance of sensitive electronic circuitry are converted instead to extremely minute amounts of heat and harmlessly released."

-- They are apparently viscoelastic in nature and act together with the load as constrained layer dampers. I’m not saying they won’t work to some degree but to deal with very low frequency vibration you need real isolation, as opposed to "vibration control." You can have both, which is why they suggest they can be used UNDER a real iso stand. At least that’s what they say. How you should support a real (mass on spring) iso stand is another issue unto itself as well as how you should mount the component on the iso stand.

"BTW, I googled "mass on spring" and I see that the spring has a non-negligible mass."

-- A spring (steel spring, air bladder or bicycle inner tube or air spring) would usually be what, 1/100 the mass of the component being isolated? Where I come from that’s negligible. My springs are the lightest in the business, coming in at around 1/200 the mass of the load.

Geoff---When you say "I can do it cheaper and better" and "My springs are the lightest in the business", may I take that to mean you market such a product? Can you direct me to a site, or provide contact/product info?