Energy damping or energy transfer?


Are there some generally accepted guidelines about which components to isolate (in terms of vibration damping) and which components to "couple" to the rack (which is also coupled to the floor)?

I freely admit to being clueless here (I'm still trying to get my head around cables and power cords), but it seems like the "brass spikes" guys are saying something completely different from the Vibrapod-type isolation guys.

Given what they're asking for these products and the potential number of components involved, it's like considering a major component upgrade.

Also, has anyone noticed once a component is isolated/coupled that either the interconnect or power cord is affected? Thanks. If this has been kicked to death in the past, just posting a link would be great.
lrdmax
You could do searches here and at Audio Asylum and spend the next month reading about this topic.

I think the only thing that responds well to "coupling" is speakers. Most electronic components benefit better from isolation, and there are dozens of ways to achieve this. If you are into the DIY thing, it ca be a fun and interesting pursuit.
If you were to do a blind AB test w/a system using after-market damping and a system using the factory supplied rubber feet, I doubt you could tell the difference. Yes, TTs need damping, but IMO the magic cones, energy dispersion crystals, maple blocks, and the like for other components are nice to look at but that's about it. No carbon fibre cone or isolation block is going to improve your CD player, amp, or preamp one iota.
I was talking about stereos one night with a chemist. He related a story to me because I was contemplating buying a Sistrum stand for my stereo which uses the coupling and draining philosophy.

He told me that at Rohm and Haas, where he works, they had the multi-million dollar electron microscopes sitting on damping pads that would hold the microscopes steady through an earthquake. Then he said, "but that nothing can stop airborne vibrations".

I went with the Sistrum stand!
Thanks for the replies. Looks like 2 to 1 in favor of isolation for components.

Among other applications, I'm working on a custom equipment rack that uses an angle iron frame with hardwood shelves. I wasn't sure if I should try to couple the shelves to the frame (by epoxying some type of small points to the shelves and having the points contact the frame) or isolate the shelves from the frame.
For isolation, I was thinking about a combination of cork and sorbothane.

Then there's the issue of isolating/coupling the components and the shelves, or, like Bojack says, DO NOTHING. ;-)
Before you take the approach that 2 out of 3 people are in favor of isolation, it might be in your best interest to try bother ways and see for yourself.

I found that too much isolation or damping had the tendency to dull the sound, where coupling brightens it. You'd be doing yourself a great disservice if you don't experiment.

An audiophile will always experiment trying to get the best sound in their system. Taking the majorities opinion and running with it blindly, especially when only three people have responded, may or may not be right for your system.
Krell man's chemist friend is correct when he said, "nothing can stop airborne vibrations".

That's why you need to expedite the transfer of resonant energy away from the component.

Of course if you'd like to trap those vibrations (captured in a moment-in-time but can only dissapate over a period of time)inside your component you can always put some kitty litter or sorbithane material underneath the component.

-IMO
I've been thinking about this topic some lately. It seems to me that the ideal system would be a combination of isolation and coupling. Depending on where you live, floor- & structure-borne vibration can really kill your hi-fi's low-level resolution, especially for vinyl playback. That's where isolation comes in--air suspensions, sandboxes, squishy feet, etc.--to keep the floor & structure-borne vibes from getting to your component. On the other hand, component-generated and airborne vibration are also destructive to low-level info. In theory, coupling seems to be the solution here, whether it's to a support that dissipates vibrations quickly (constrained layer platforms, some solid wood platforms) or to a support that resists movement in the first place (heavy stone slabs and the like). So my theoretical ideal would be to couple the component to a vibration 'sink', and then to isolate that system via some kind of suspension. This ignores energy storage in suspensions or coupled platforms, and probably other issues I'm unaware of.

This idea is based in part on personal experience. I live near a busy intersection. By far the best thing I've put under my turntable--an unsuspended Rega P3--is a DIY, inner-tube-based air platform. The improvement is not subtle. My theoretical explanation is that the air suspension is isolating my TT from traffic-generated vibrations. Second part of my idea is based on my experience that my 'table sounds better if it has hard feet between it and the suspended platform (made of mdf). The setup is pretty crude, but it will remain in my system until I buy or make something prettier that does the same thing.

I've also put my tube amp on a similar air-suspended platform, but I don't hear any obvious differences with it. With speakers, common sense tells me that the speaker cone's mass is too small a fraction of the cabinet's mass for it to make a difference, but damned if I don't like my stand-mounted speakers better on spikes than on blu-tak. This could have to do with cabinet resonances rather than movement of the cabinet relative to the speaker cone though.

Brent
Krell man, you're right. My "statistical summary" was kind of tongue in cheek; sometimes kind of hard to get that across in print. Given the frequency with which this topic is apparently covered around here, I guess I didn't really expect a lot of posts, hence my summary.

I would like to try both approaches in developing my rack. Without going to the expense of buying lots of brass cones, any suggestions for testing out the coupling idea? Thanks.
Cbrentc, I've thought about similar turntable damping tweaks. 2 thoughts come to mind, there.

1. How about putting that inner tube in a solid box with the inner tube inflated just enought to stick above the top of the box so that the shelf that the TT sits on still floats slightly above the box, but the box itself restricts any lateral type movements that result from vibrations.

2. Acknowledging Krell man and Stehno's assertion that "nothing can stop airborn vibrations", what if you had a large dust cover that could cover the entire TT and rest on the shelf itself and then weight that down with something quick? Would that work in helping stop airborn vibrations?

It wouldn't be a good solution for heat-producing components, but for a turntable? Maybe....

Anyone ever try shipping peanuts (those styrofoam things) as damping material?
If you want to maintain dynamic coherence within your system then pursue direct coupling of resonant energy and its discharge to the the higher mass or ground. You must focus and direct energy, shorten.. and not impede or slow its path. I agree with Stehno make it go away as quick as you can. In my opinion mechanical damping of most electro-mechanical devices is analogous to the variable and mostly deleterious effects of capacitor coupling within speakers and electronic audio components. Tom

1. How about putting that inner tube in a solid box with the inner tube inflated just enought to stick above the top of the box so that the shelf that the TT sits on still floats slightly above the box, but the box itself restricts any lateral type movements that result from vibrations.

That's almost exactly what I'm using. Only difference is that the top of the platform is slightly lower (~1/8") than the top of the box, but there's a big enough gap that the platform doesn't touch the box. It began life as a sandbox. I recently dumped the sand and stuck a 16" BMX tire tube in there. As I said, not elegant, but if it works...


2. Acknowledging Krell man and Stehno's assertion that "nothing can stop airborn vibrations", what if you had a large dust cover that could cover the entire TT and rest on the shelf itself and then weight that down with something quick? Would that work in helping stop airborn vibrations?

I've had similar thoughts, maybe putting a turntable inside a cabinet, & then isolating the 'table from the cabinet/shell. Rega recommends listening to their turntables with the lid on. I would guess that this is to isolate the cartridge & arm from airborne vibration. Consensus on the web is that the lid resonates and transmits airborne vibrations to the plinth & the rest of the 'table, which is sonically detrimental. I prefer listening with the lid off myself.

Brent
Generally it is better to dampen vibrations. Most often blu-tak does the job. Sometimes a very flappy & resonant speaker enclosure (poor design) may benefit from anchoring or coupling it to the stand and the floor as this may reduce certain resonances or shift them below the audible range.

If you want to maintain dynamic coherence within your system then pursue direct coupling of resonant energy and its discharge to the the higher mass or ground.

That's probably true in most cases. In my case, there's likely more energy coming from the structure of my building than from my turntable. At least that's my guess as to why I like my turntable better with the airbox. But, again, I live near a busy intersection, and I live on the third floor of an apartment building. Between the traffic and other residents' activities & appliances, I may have a higher than average amount of building-borne vibration to deal with.

Brent
Cbrentc,

LOL ....your thoughts make me think that someone should extend their noise cancelling headphones into a device to cancel vibrations....all you need is a 3 axis accelerometer tied to the device you want to stabilize and then a negative feedback loop to a 3 axis vibration servo that actively vibrates the device in the opposite way and cancels out all vibration ...airborne or otherwise.....this is the kind of stuff which is used in inertial guidance systems...it would not be cheap! (Of course the device would need its own internal damping...but this is common already)

Worth a patent perhaps?
Shadorne, in fact the vibration servo device could be another small speaker installed in the stand or support device! Brillant idea!
Bob P.
What would be the resolution and the bandwidth of the servo?
It's been our experience that all different products perform differently, and even can be different in various applications.
Primarily, the idea of vibration transfer would be aimed at taking the vibrations away from the equipment and down into a larger mass which is capable of dissipating the vibrational energy.
The idea of local damping would be aimed at trying to dissipate the vibrational energy right there at the equipment.
Basically, the difference in need would dictate the product used, because if the need is greater than the local damping product used can provide, then the overload of vibration will be reflected back into the components as the Zener Viscoelastic Model demonstrates.
In a highly vibration-laden environment such as an audio listening room, it is very likely that any small viscoelastic product would be overloaded very quickly, and thus return the vibrations into the components, causing smear.
To deal with large amounts of vibrational energy, a means to transfer the energy to something which has the capacity to dissipate those vibrations more effectively(large mass, house, earth) might be a better choice in many applications.
There are products which are designed to do this.
Some are more effective than others.
Shadorne,

I'll check the Patent Office website & get back to you. . .

As to my thoughts above, it's all speculation. I do prefer the way my TT sounds when it's 'suspended', though. Maybe it would sound even better with the listener suspended too. I'll look for patents of 'audiophile swings' while I'm on it.

Brent
What is dynamic coherence, and how do vibrations affect it? Thanks -- anyone.
My stand has a door on it which stops airborne vibration as far as I can tell. As soon as I got it, I noticed my stereo was less bright.
Cdc -- Clever. I've noticed, however, that doors tend to reflect light, thus making the system more bright. That's one reason I took the door off my system.