Vibration elimination vs. Coupling / Tuning

byteme · « **on:** 3 Oct 2003, 03:51 pm »

Here's a question I've been trying to read up on lately and get some information about.

There seems to be two general (probably more) theories or camps from what I've found on how components should be, for lack of a better word, mounted on a shelf (or floor/stand in the case of speakers). This is only as it pertains to components and not intended to extend to eliminating all vibration by stapling your cables to wood boards for example.

One, is to try and couple it to the shelf media using cones, etc made of carbon fiber, brass, ceramics, you name it. Sometimes this is done into woods of various types. However, by doing so aren't you adding the resonance of the wood/brass/ceramic into the equation, effectively tuning the system with whatever material you use?

The other method I've seen is to try and isolate the component and keep if free from vibration. There are many things tried for this too, from used tennis balls, vibrapods, reverse pole magnets to "float" the component, sorthobane, bike innertubes, etc. The argument here obviously is that vibration is bad and to put something between the component and shelf to avoid incoming, and in some cases absorb outgoing vibrations from the component.

Are these two mutually exclusive? If so, which route to go? Is it the same answer for ALL components or not (i.e. should speakers be coupled and transports be isolated?) For example, is it bad that I've got my speakers on 6 vibrapods which sit on a hunk of MDF with three spiked feet into the floor? Is this the best of both worlds or does one (the vibrapods) negate the effects of the spikes? Should I kill the vibrapods and just use spikes or kill the spikes and put the vibrapods on Marble or granite or MDF?

Hantra · « **Reply #1 on:** 3 Oct 2003, 04:14 pm »

Quote from: byteme

However, by doing so aren't you adding the resonance of the wood/brass/ceramic into the equation, effectively tuning the system with whatever material you use?

Yes, you are. Different materials used for coupling will sound different. Usually the materials known for faster drainage sound best IMO. Brass drains very fast, and I have found that all around, it's a good coupler b/c it's very close to the chassis material most of the time.

On some occasions, I have found wood to be equally as effective with different effects per the type of wood. Woods that are good IMO are myrtle, birch, and sometimes maple. Stay away from pine, and soft woods. Redwood is the worst wood I have ever heard for this use. I'd rather use tennis balls! Well. . Not really. It actually sounds much better than the best "isolation" you can get with squishy materials.

Quote from: byteme

Are these two mutually exclusive? If so, which route to go? Is it the same answer for ALL components or not

I'd say they are mutually exclusive unless you are using a turntable. The rules don't apply there. In most every other component, drainage actually helps several orders of magnitude more than "isolation". Isolation in audio is like the tooth fairy. It doesn't exist. It's physically impossible for all but the .0001 percentile who can have perfect conditions to isolate their gear from airborne vibrations.

Even then, there is so much chaotic vibration inside your gear that's created by your gear, one should still drain off as much as possible and as quickly as possible.

L8r,

B

gary · « **Reply #2 on:** 3 Oct 2003, 04:56 pm »

here are my opinions on the issue: you want to isolate your components from vibrations coming up through the supports, add mass to them, and damp the remaining vibrations, which will pretty much be airborn ones. i've written a white paper on this (if you want to read it click on the 'vibration and audio link' at www.pandathumbaudio.com) but the basic approach is this:

start with something stiff, mdf or a cutting board is fine.

next put down an innertube, barely inflated (you can get 12" tubes at most bike shops, mcmaster.com carries them down to 5")

on top of the innertube goes a granite surface plate. (grizzly.com carries them, but shipping gets expensive for the larger ones)

on top of the granite goes compliant footers that will convert vibrational energy to heat.

finally, your component goes on top.

while most approaches common in the audiophile world might do one thing well (or one thing less than well), this gives you isolation (the innertube), mass coupling (the granite), and passive damping (the footers) at the same time. naturally i'd recommend my own footers, but there are others that would work well, such as the ones from herbie's audio lab. the total cost will be under $100 and you'll end up with something that's a very, very good approximation of a $100k+ newport vibration isolation table. i've got my tube amp supported this way, and the improvement is not subtle.
http://www.pandathumbaudio.com/download/System2.jpg

as for speakers, i'd suggest you try swapping out the vibrapods for some sorbothane. you can buy a sheet ~0.2" thick from mcmaster.com for less than $20, and cut it into small square pieces. the size would depend on the weight of your speakers, i could help you with the place to start but it'd involve trial and error to find what's optimal. this should give you most of the benefits you hear with the vibrapods, and at the same time tighten the bass up nicely.

-gary

gary · « **Reply #3 on:** 3 Oct 2003, 05:09 pm »

Quote from: Hantra

In most every other component, drainage actually helps several orders of magnitude more than "isolation". Isolation in audio is like the tooth fairy. It doesn't exist.
B

could you elaborate on what you mean by "drainage"?
it sounds like you are confusing vibration with a liquid that's only going to flow downwards with the pull of gravity. has someone told you that spikes and cones are "mechanical diodes"?

-gary

Psychicanimal · « **Reply #4 on:** 3 Oct 2003, 05:21 pm »

Quote from: gary

could you elaborate on what you mean by "drainage"?
it sounds like you are confusing vibration with a liquid that's only going to flow downwards with the pull of gravity. has someone told you that spikes and cones are "mechanical diodes"?
-gary

This is going to get really good--Byteme started it all!

Drainage? Vibration sink? Is that correct?
Hmm, ask anyone who has used non-resonant, Caribbean Moca wood...

_scotty_ · « **Reply #5 on:** 3 Oct 2003, 05:44 pm »

Quote from: byteme

Here's a question I've been trying to read up on lately and get some information about.

There seems to be two general (probably more) theories or camps from what I've found on how components should be, for lack of a better word, mounted on a shelf (or floor/stand in the case of speakers). This is only as it pertains to components and not intended to extend to eliminating all vibration by stapling your cables to wood boards for example.

One, is to try and couple it to the shelf media using c ...

I thought I would toss this idea into the mix. Based on my personal experience. I am using a Stan Warren Modified SACD1000. I have friends in Chicago who insisted I try Darumas under my player.This is a device that is intended to isolate a component from horizontally propagated
vibrations present in the environment. Electron microscope users and manufacturers whose production processes are susceptible to structure born vibration use devices that isolate them from both vertical
horizontal vibrations. These people have an objective reference they can see if the device actually does something or not. Snake oil and magic
materials won't work here. I tried the Darumas and they work. Apparently the Circuitry in the SACD 1000 is revealing enough after Stan modifies it
to tell you how important proper isolation is. Ideally I would purchase an product intended for industrial use and isolate the SACD1000 in both planes but my wallet isn't deep enough. I have tried them under preamps and amps with no observable effect. In fact my preamp doesn't seem to be affected by anything at all. Yes, it is plugged into the wall. The power amp likes a constained layer dampening footer I constructed out of layers of ceramic tile, cork, and Dynamat Super. I would suggest trying the Darumas under your player or transport and see what you hear. YMMV
but they worked for me.

byteme · « **Reply #6 on:** 3 Oct 2003, 05:50 pm »

So, Hantra, can I assume you're more in the coupling camp, but using something that has properties which absorb and drain off vibration, ex. Brass footers?

Gary, what I'm reading from you is that vibration is the enemy and go to many layers to defeat it. Your sandwich reciepe is similar to those I've seen before. I've read your white paper. The effect that your after (specifically in this instance with Sorthobane) is exactly the same as vibrapods aim at. My question to you then would be, why Sorthobane vs. Vibrapods?

Psychic,

In your use of the Moca wood (by the way, what is your source for this? Is it readily available?) are there other things used as well? Do the components sit on spikes into the wood or directly on the wood with thier standard feet. Or are you suggesting another sandwich reciepe? If so, what is it?

Scotty

Where do you get these suckers?

Thanks!

gary · « **Reply #7 on:** 3 Oct 2003, 06:21 pm »

Quote from: byteme

Gary, what I'm reading from you is that vibration is the enemy and go to many layers to defeat it. Your sandwich reciepe is similar to those I've seen before. I've read your white paper. The effect that your after (specifically in this instance with Sorthobane) is exactly the same as vibrapods aim at. My question to you then would be, why Sorthobane vs. Vibrapods?

i have never used vibrapods, or even seen them for that matter. i have read their patent, and IMO it's not overly impressive (the patent that is, not necessarily their design). if anyone wants to see it, i have it in pdf format and could certainly post it or email it. anyway, according to their claims what they're trying to do is isolate vibration with the geometric design of the vibrapod.

i am, on the other hand, trying to damp vibration with a viscoelastic polymer. and when it comes to converting mechanical energy (vibrations) to heat, sorbothane works better than any other material i know of. so to sum up i'm taking advantage of the material properties of sorbothane, instead of a mechanical design such as the vibrapod. hopefully that makes sense to you. (of course sorbothane supports have to be designed properly in order to work right, and as i point out in the white paper i feel i'm the only one who's bothered to do this for audio applications).

-gary

Hantra · « **Reply #8 on:** 3 Oct 2003, 06:21 pm »

What is drainage? It should be obvious. Drainage is providing outlets for the vibration to leave the component. Faster is better here since we ALL agree that non-sympathetic vibration is bad.

Quote

add mass to them, and damp the remaining vibrations, which will pretty much be airborn ones

This won't work man. There is no way that energy can escape a component if it's sitting on a bouncy rubber innertube, or whatever else you put it on that doesn't allow vibration to escape. Your components generate a hell of a lot more chaotic, and audible vibration than does your floor.

Therefore, it's the lesser of two evils. You can't attack both if you are in the 99.999 percentile. If you can only choose one, I submit that drainage/coupling is far superior, and that can be proven with listening tests, AND science.

Merely adding mass for the sake of adding mass may damp certain frequencies, but when you lower the resonant frequency, you lengthen the time that an object will vibrate. And they all WILL vibrate regardless of what we do.

Quote

when it comes to converting mechanical energy (vibrations) to heat, sorbothane works better than any other material i know of

Can you prove this? I didn't think so. . .

B

gary · « **Reply #9 on:** 3 Oct 2003, 06:54 pm »

Quote from: Hantra

What is drainage? It should be obvious. Drainage is providing outlets for the vibration to leave the component. Faster is better here since we ALL agree that non-sympathetic vibration is bad.

how about this: you are entitled to your own opinions, you are not entitled to your own facts (i think strom thurmond said it). just because you use a term like "drainage" doesn't make it physically viable.

Quote from: Hantra

This won't work man. There is no way that energy can escape a component if it's sitting on a bouncy rubber innertube, or whatever else you put it on that doesn't allow vibration to escape. Your components generate a hell of a lot more chaotic, and audible vibration than does your floor.

um, what is this "chaotic vibration", and how is it generated? are you talking about vibration due to SPL in the air? the point of the innertube is to isolate the component from vibrations that would come up through whatever is supporting it. and you're right, vibrations aren't going to be dissipated through the tube. that is, in fact, the whole point of my design.

Quote from: Hantra

Therefore, it's the lesser of two evils. You can't attack both if you are in the 99.999 percentile. If you can only choose one, I submit that drainage/coupling is far superior, and that can be proven with listening tests, AND science.

ah. coupling is a better word, thank you.

Quote from: Hantra

Merely adding mass for the sake of adding mass may damp certain frequencies, but when you lower the resonant frequency, you lengthen the time that an object will vibrate. And they all WILL vibrate regardless of what we do.

and this is why the sorbothane is suggested. the microphonic vibration of the granite ("ringing" as it is often called) will be greatly attenuated when passing through the sorbothane. if you want i can work out the numbers, but it's well over a 50dB drop and probably more like 100dB. and remember, we're talking about very small amplitudes to begin with. additionally, sorbothane will damp the airborn vibrations in the component very effectively.

Quote from: Hantra

Quote:
when it comes to converting mechanical energy (vibrations) to heat, sorbothane works better than any other material i know of

Can you prove this? I didn't think so. . .

no offense, but did you read what i said? try again, and pay special attention to the part where i said "better than any other material i know of". it's pretty easy for me to prove that i don't know of anything that works better. and if you do know of anything that works better than sorbothane in this application i'd certainly like to hear about it.

-gary

[edited to fix a typo]

byteme · « **Reply #10 on:** 3 Oct 2003, 07:03 pm »

Quote from: gary

are you talking about vibration due to SPL in the air? the point of the innertube is to isolate the component from vibrations that would come up through whatever is supporting it. and you're right, vibrations aren't going to be dissipated through the tube. that is, in fact, the whole point of my design.

-gary

Gary,

Here's where I don't get it about the sandwich theory. Based on this reciepe:

Component
Sorthobane (or other) foot
granite
innertube
rack shelf

Isn't the innertube redundant? Why wouldn't just the sorthobane footer be enough? If it's going to take the airborne vibrations and convert them to heat isn't it also capable of converting the vibration coming from the rack shelf into heat? And what of the vibration the component itself creates - what happens to those in this equation?

And, I'm not trying to argue I'm trying to learn...

Hantra · « **Reply #11 on:** 3 Oct 2003, 07:18 pm »

Quote

what is this "chaotic vibration", and how is it generated? are you talking about vibration due to SPL in the air?

Dude, go back and read what I said. Nevermind. Let me post it for you. . .

I said:

Quote

Your components generate a hell of a lot more chaotic, and audible vibration than does your floor.

When I say components, I am not talking about speakers. I'm talking about the components we are trying to "isolate". Have you never put your hand on top of a CD player, or even an ultra high-end transport, and felt the vibration the component created? ? ?

Even if it's not mechanical vibration, electrical vibration is also something that needs to have an outlet. You even allude to electrical vibration in your "white paper", which is why I am surprised you wouldn't want to couple the component to let that out.

Quote

no offense, but did you read what i said? try again, and pay special attention to the part where i said "better than any other material i know of".

Heh. . That makes sense now. So basically you have a "white paper" on something that you have no phyical evidence of at all, right? And all this "knowledge" in the "white paper" is coming from your own personal listening preferences, and not facts?

I'm sorry man. . . But to date, I know of no one that has been able to measure any amount of vibrational energy being converted to heat with Sorbothane, or anything like that.

I'm not disrespecting or anything, but I would just be a bit more careful when you are presenting things as if they are FACTS, and not just your own preferences, and ideas.

B

gary · « **Reply #12 on:** 3 Oct 2003, 07:19 pm »

Quote from: byteme

Gary,

Here's where I don't get it about the sandwich theory. Based on this reciepe:

Component
Sorthobane (or other) foot
granite
innertube
rack shelf

Isn't the innertube redundant?

wow that was a quick response...
the innertube is indeed somewhat redundant. however, the system will work much better with the innertube in place than without it. and yes, i've tried both.

Quote from: byteme

Why wouldn't just the sorthobane footer be enough? If it's going to take the airborne vibrations and convert them to heat isn't it also capable of converting the vibration coming from the rack shelf into heat? And what of the vibration the component itself creates - what happens to those in this equation?

the problem is that sorbothane (or any other similar support) simply cannot attenuate large-amplitude vibrations well enough, and this is where the innertube comes into play. to test this, i put a small "pool" of water on one of my components and stomped on the floor next to it with my foot while looking at the reflection of a distant image on the surface of the water. with only the sorbothane in place, the image was distorted by waves on the surface of the water. adding the innertube yielded a very significant visible improvement.

anyway, i'm working on a way to quantitatively measure component vibration, but it's not easy, even with the right equipment. hopefully i'll get there sooner or later, and then i'll be able to measure different approaches/products and compare them with hard numbers.

Quote from: byteme

And, I'm not trying to argue I'm trying to learn...

well, both is fine too

-gary[/i]

gary · « **Reply #13 on:** 3 Oct 2003, 07:43 pm »

Quote from: Hantra

Have you never put your hand on top of a CD player, or even an ultra high-end transport, and felt the vibration the component created? ? ?

Even if it's not mechanical vibration, electrical vibration is also something that needs to have an outlet. You even allude to electrical vibration in your "white paper", which is why I am surprised you wouldn't want to couple the component to let that out.

i really think you're hung up on this "drainage"/"mechanical diode" thing. the sorbothane is indeed coupling the component to the granite, and it will attenuate any vibration that passes through it. it will therefore damp the vibrations of the component. now if you want to, you can think of the sorbothane footer as a "drain" in the same way you think the cones & spikes behave. i'll cringe, but you can do it.

Quote from: Hantra

Heh. . That makes sense now. So basically you have a "white paper" on something that you have no phyical evidence of at all, right? And all this "knowledge" in the "white paper" is coming from your own personal listening preferences, and not facts?

my knowledge is coming from my education, background, and studying the issue. in this case i was emphasizing to you that i never claimed sorbothane to be the best material for vibration damping, just the best i knew of.

Quote from: Hantra

I'm sorry man. . . But to date, I know of no one that has been able to measure any amount of vibrational energy being converted to heat with Sorbothane, or anything like that.

well, sorbothane is used in plenty of industrial applications by plenty of people who have measured its performance quantitatively. i can assure you that if that wasn't the case, they wouldn't be running a profitable business. after work i'll post some sources for you and anyone else to read.

Quote from: Hantra

I'm not disrespecting or anything, but I would just be a bit more careful when you are presenting things as if they are FACTS, and not just your own preferences, and ideas.

it is a fact that vibration is attenuated when passing through a viscoelastic material such as sorbothane. how's that? furthermore i never made any subjective claims in the white paper, or anywhere else on my site for that matter.

-gary

Hantra · « **Reply #14 on:** 3 Oct 2003, 07:58 pm »

Quote

i really think you're hung up on this "drainage"/"mechanical diode" thing.

I never ever said anything about a "mechanical diode". In fact, I am unaware that such a device exists. But that's just those crazy laws of physics talking. they probably don't really exist anyway. . .

Quote

you can think of the sorbothane footer as a "drain"

Not hardly man. Sorbothane doesn't drain any vibration, so why would I consider it similar to a drain?

Quote

my knowledge is coming from my education, background, and studying the issue.

Well that's good. I think you're oversimplifying your studying by omitting some MAJOR sources of vibration. Ones to which you allude in the "white paper".

Quote

well, sorbothane is used in plenty of industrial applications by plenty of people who have measured its performance quantitatively.

If you can point me toward anyone credible who has ever measured the exact amount of energy converted to heat by Sorbothane, I will admit my wrong. I just don't think it has ever happened.

Secondly, it's a completely different thing to measure the "performance" of Sorbothane, and measure its ability to magically morph energy into heat. Basically all Sorbothane does is bounce vibrations which are trying to flow toward the ground (those freaky physicists again!), right back into the component at a different frequency. HOW can that be good?

Quote

it is a fact that vibration is attenuated when passing through a viscoelastic material such as sorbothane.

Like I said. . Show me the measurements of energy converted to heat.

Thanks,

B

_scotty_ · « **Reply #15 on:** 3 Oct 2003, 08:12 pm »

Quote from: gary

no offense, but did you read what i said? try again, and pay special attention to the part where i said "better than any other material i know of". it's pretty easy for me to prove that i don't know of anything that works better. and if you do know of anything that works better than sorbothane in this application i'd certainly like to hear about it.

-gary

[edited to fix a typo]

Excuse me, Hantra and Byteme,but both of your claims can be substantiated or refuted by actual existing measurement technologies. If you use solid state strain gauge accelerometers in two planes you can measure the before and after effect of your various vibration control strategies.

gary · « **Reply #16 on:** 3 Oct 2003, 08:15 pm »

Quote from: Hantra

I never ever said anything about a "mechanical diode". In fact, I am unaware that such a device exists. But that's just those crazy laws of physics talking. they probably don't really exist anyway. . .

well, the term "drainage" implies uni-directionality. and it's usually mentioned in conjunction with the term "mechanical diode". dissipation would be a better one to use, so long as you understand that vibrations will go in both directions: they'll be coming up through the spikes as well.

Quote from: Hantra

Secondly, it's a completely different thing to measure the "performance" of Sorbothane, and measure its ability to magically morph energy into heat. Basically all Sorbothane does is bounce vibrations which are trying to flow toward the ground (those freaky physicists again!), right back into the component at a different frequency. HOW can that be good?

now i understand your misconceptions. sorbothane doesn't just 'bounce' vibrations back. they pass through it, and lose energy as they do. by definition, a viscoelastic such as sorbothane is a damped spring. now when you push on a perfect spring and release, the same energy comes back. but when you push on a damped spring and release, less energy comes back. conservation of mass says the energy has to go somewhere, so where does it go? heat. it's the same phenomenon that makes the ride in your car smooth... your shocks are damped springs in much the same way that the sorbothane is. if you do a google search for terms like "system dynamics" dashpot and viscoelastic you'll probably find some better explanations than that.

-gary

gary · « **Reply #17 on:** 3 Oct 2003, 08:33 pm »

Quote from: _scotty_

Excuse me, Hantra and Byteme,but both of your claims can be substantiated or refuted by actual existing measurement technologies. If you use solid state strain gauge accelerometers in two planes you can measure the before and after effect of your various vibration control strategies.

absolutely. another alternative would be to use two non-contact laser position sensors hooked up to an oscilloscope or DAQ board in a computer. i'd love to do that, but unfortunately if i did i could probably sell footers for $20 a set until i died without ever turning a profit

not that i'm making anything on these anyway, it's basically a write-off against some consulting income.

-gary

Hantra · « **Reply #18 on:** 3 Oct 2003, 09:38 pm »

Quote

Hantra and Byteme,but both of your claims can be substantiated or refuted by actual existing measurement technologies.

Maybe so. But the difference is that I don't have a "white paper", and I don't purport to have any physical evidence other than listening, AND I'm not selling a product.

Gary's claims on the other hand can not be proven with science. If they could, he would have come back with some.

Just trust your ears. It's no trouble at all to get both, and listen. It's easy to hear the difference. You either like slow, nasty sound where the vocalists sound drunk, or you don't.

L8r,

B

gary · « **Reply #19 on:** 3 Oct 2003, 10:21 pm »

Quote from: Hantra

Gary's claims on the other hand can not be proven with science. If they could, he would have come back with some.

this conversation is clearly over.

for anyone actually interested in learning about the subject, the following paper is worth reading:
http://www.csaengineering.com/actsys/viscoelasticmaterials.shtml

here is the material properties pdf document from sorbothane, which shows the impulse response and transmissibility of the material along with a couple of other polymers for comparison (at the bottom):
http://www.sorbothane.com/PDF/sor_matprop.pdf

here is an excellent paper on viscoelastics and their use in damping:
http://www.anatrol.com/pdf/white_papers/Insight.pdf

here is a paper about advances in viscoelastic damping in the automotive industry:
http://www.me.mtu.edu/~mrao/india-usa_u011.pdf

-gary