So my original statement was this: "Of course it's important to ensure the platter bearing and tonearm are sufficiently isolated from each other..."
In this context I was referring to isolation from unwanted vibrations. I wasn't suggesting any sort of flexibility here. And don't really see how, even if I were referring to physical isolation, flexibility would be implied.
Which is why I was, and I suppose still am, confused by your initial response. Regardless, and unless there's still something you think I'm misunderstanding, both the direct drive motor and the tonearm will be rigidly mounted to the plinth.
The challenge remains - and this is why I made the statement in the first place - how to design a plinth that has characteristics capable of ensuring that the two components are isolated from each other in terms of not catching each others' unwanted transmissions.
Your original statement about isolating a tonearm and platter/motor assembly FROM EACH OTHER in itself leads the reader to believe that physical/mechanical isolation of these components FROM EACH OTHER is suggested.
It's all about the wording.....
If you had said "From external vibrations due to possible speaker feedback", which is the understood norm in turntable designs, this thread would not be ongoing with these explanations.
Your "In this context I was referring to isolation from unwanted vibrations."
would have been better understood by stating the specific source (aka external or speaker-driven) vibration.
The description by MS is clearly confusing by itself, and contains the usual marketing talk, and since you are not experienced in understanding turntable design, of course you would wonder about this "isolation" thing.
Your concerns about a Direct Drive motor (and its possible vibrations) also suggests your lack of understanding about them, and we've provided you with the information to put your mind at ease about that.
And with that, I'll leave any further commentary to the others here.
The options available to come to understand how changing a material will change a Resonant Mode within the TT>Tonearm>Cartridge is relatively easy to achieve.
I have a history of exchanging materials that are coupled to a TT and find this simple interaction one of the most satisfying parts of owning a TT, as much can be achieved from a little investigation.
I am aware of those who have experiences and have shared in a few of the experiences, that has shown how noticeable changed to a SQ can be achieved by exchanging Tonearm Mounting Plates if able to be exchanged.
From my own experiences I have discovered SQ Changes can be achieved
by exchanging Head Shells to differing materials and producing different Tracking Weights.
It can be achieved by trying different materials as a Platter Mat and combinations of different materials used on a Platter.
It can be produced by using different footer materials or footer designs, along with Sub Plinths produced in different materials or composites of materials.
For the OP the following is a deviation from your initial inquiry, but as you are inquisitive about this subject, I have offered a further contribution.
To get the project underway, choosing the Material for the Plinth is maybe not the most important consideration.
As there are already material choices on your list that are known for their valued properties as a Plinth Material.
If a home built plinth was produced from easy to acquire material,
it will be a good exercise to refine a few machining skills and help in producing a Plinth to be used with the intent of learning about the environment that is to be produced for the TT be set up in and function in.
My in use TT Stand only supports a TT and the Phonostage.
I have always liked to investigate with multiple materials, so went down a route that enables this to happen
I opted not to go for the Wall mounted Bracket as my other Source Devices are on a Wall Mounted Rack.
The TT Mounting Assembly of materials is purpose produced from the Ground Up to offer as much Isolation as possible.
The Selected Materials are used for their impressions they have made on me over the years.
There is no Science behind the design, just good old Building Philosophy and using ears as a Judge.
The Base Footers are Granite Blocks seated on a Short Weave Carpet, laid on top of the Granite Blocks is a Dense Structural Foam .
The Base for the Stand is a 12mm Steel Sheet, seated on Dense Foam.
The Racks Frame is made from Two Timber Species and is set upon the
Steel Sheet.
Under the Granite Shelving of the Rack is more Structural Foam, and on top of the Granite Shelve is more Dense foam.
Sitting on the Dense Foam is a Box to serve as a Flotation Design,
it is a Male / Female Two Piece Box Made from a increased compression
type of plywood.
The Upturned Female Section of the Box has a purpose made Internal Base that acts as a Psuedo Pnuematic Support for the Male insert section of the Box.
On the Top of the Male Insert are Four Audio Technica AT 616 Footers.
On the AT 616 Footers is a Sub Plinth made from a extremely High Compressed Foam, which is one of my favourite attenuation materials,
it is used as shelves elsewhere.
On the Sub Plinth are 4 X Solid Tech 'Feet of Silence' Footers and on to the
'Feet of Silence' is a the 20mm Thick MU25 TT Plinth.
I have exchangeable Head Shells and a variety of materials as Platter Mats, as well as a Phosphor Bronze Platter (yet to be used).
To get to the level of Performance I am experiencing has not been too expensive, without the Branded Footers Footers and the Long Term owned Rack, it was cheaper than purchasing Panzerholz as a Plinth Blank.
As some of the materials are purchased as used, and I repurposed these materials.
It has required a willingness to trial, but also kept the enjoyment of the replays as part of the process, as the system is only temporarily not used, while a Tier is added or exchanged.
The perceived improvement at certain times, when introducing a Tier of Material was very noticeable, and some added materials were perceived as offering very little in improvement, and some were seen to offer a little more of something that was present for the Better.
With a Mounting Assembly > TT > Tonearm > Cartridge, it is commonly a host of little changes that as a whole will bring one substantial change.
If the mounting for the Plinth is as good as can be achieved in a set environment, allowing for any budget limitations, there is a great base for a project to be achieved.
When the Final Materials are selected for the End Game Plinth, it can be a good assurance that there has been a investigation before hand to enable it to deliver its very best, when mounted on a Produced Assembly of materials.
My experience is at present, I have the Valued Materials for a Plinth in my Possession, but with the present arrangement for the Mounting, I am not feeling the need to rush into making a change.
I am not suggesting at any time that such a Assembly of Materials is gathered to produce a mimic to this Mounting System, although I am sure it would impress with its performance enhancing properties.
The general idea is that there are more simple options to be trialled and investigated and the learning to be had will serve as a good starting place, to begin to understand a variety of attenuation that can be achieved and start to see where you lean toward.
I have a history of exchanging materials that are coupled to a TT and find this simple interaction one of the most satisfying parts of owning a TT, as much can be achieved from a little investigation.
I am aware of those who have experiences and have shared in a few of the experiences, that has shown how noticeable changed to a SQ can be achieved by exchanging Tonearm Mounting Plates if able to be exchanged.
From my own experiences I have discovered SQ Changes can be achieved
by exchanging Head Shells to differing materials and producing different Tracking Weights.
It can be achieved by trying different materials as a Platter Mat and combinations of different materials used on a Platter.
It can be produced by using different footer materials or footer designs, along with Sub Plinths produced in different materials or composites of materials.
For the OP the following is a deviation from your initial inquiry, but as you are inquisitive about this subject, I have offered a further contribution.
To get the project underway, choosing the Material for the Plinth is maybe not the most important consideration.
As there are already material choices on your list that are known for their valued properties as a Plinth Material.
If a home built plinth was produced from easy to acquire material,
it will be a good exercise to refine a few machining skills and help in producing a Plinth to be used with the intent of learning about the environment that is to be produced for the TT be set up in and function in.
My in use TT Stand only supports a TT and the Phonostage.
I have always liked to investigate with multiple materials, so went down a route that enables this to happen
I opted not to go for the Wall mounted Bracket as my other Source Devices are on a Wall Mounted Rack.
The TT Mounting Assembly of materials is purpose produced from the Ground Up to offer as much Isolation as possible.
The Selected Materials are used for their impressions they have made on me over the years.
There is no Science behind the design, just good old Building Philosophy and using ears as a Judge.
The Base Footers are Granite Blocks seated on a Short Weave Carpet, laid on top of the Granite Blocks is a Dense Structural Foam .
The Base for the Stand is a 12mm Steel Sheet, seated on Dense Foam.
The Racks Frame is made from Two Timber Species and is set upon the
Steel Sheet.
Under the Granite Shelving of the Rack is more Structural Foam, and on top of the Granite Shelve is more Dense foam.
Sitting on the Dense Foam is a Box to serve as a Flotation Design,
it is a Male / Female Two Piece Box Made from a increased compression
type of plywood.
The Upturned Female Section of the Box has a purpose made Internal Base that acts as a Psuedo Pnuematic Support for the Male insert section of the Box.
On the Top of the Male Insert are Four Audio Technica AT 616 Footers.
On the AT 616 Footers is a Sub Plinth made from a extremely High Compressed Foam, which is one of my favourite attenuation materials,
it is used as shelves elsewhere.
On the Sub Plinth are 4 X Solid Tech 'Feet of Silence' Footers and on to the
'Feet of Silence' is a the 20mm Thick MU25 TT Plinth.
I have exchangeable Head Shells and a variety of materials as Platter Mats, as well as a Phosphor Bronze Platter (yet to be used).
To get to the level of Performance I am experiencing has not been too expensive, without the Branded Footers Footers and the Long Term owned Rack, it was cheaper than purchasing Panzerholz as a Plinth Blank.
As some of the materials are purchased as used, and I repurposed these materials.
It has required a willingness to trial, but also kept the enjoyment of the replays as part of the process, as the system is only temporarily not used, while a Tier is added or exchanged.
The perceived improvement at certain times, when introducing a Tier of Material was very noticeable, and some added materials were perceived as offering very little in improvement, and some were seen to offer a little more of something that was present for the Better.
With a Mounting Assembly > TT > Tonearm > Cartridge, it is commonly a host of little changes that as a whole will bring one substantial change.
If the mounting for the Plinth is as good as can be achieved in a set environment, allowing for any budget limitations, there is a great base for a project to be achieved.
When the Final Materials are selected for the End Game Plinth, it can be a good assurance that there has been a investigation before hand to enable it to deliver its very best, when mounted on a Produced Assembly of materials.
My experience is at present, I have the Valued Materials for a Plinth in my Possession, but with the present arrangement for the Mounting, I am not feeling the need to rush into making a change.
I am not suggesting at any time that such a Assembly of Materials is gathered to produce a mimic to this Mounting System, although I am sure it would impress with its performance enhancing properties.
The general idea is that there are more simple options to be trialled and investigated and the learning to be had will serve as a good starting place, to begin to understand a variety of attenuation that can be achieved and start to see where you lean toward.
There is a school of thought that ideally the turntable bearing and tonearm should vibrate (or not vibrate) in UNISON, that is, tightly coupled. If they vibrate independently then their contact point when the stylus meets the groove would create a chasm and vibrate more than the sum of the two components, hence the use of grommets at the tonearm base a la SME is not ideal. The COMBINATION of tonearm and turntable bearin should be isolated or decoupled from extra vibration such as speakers and footfall noise, etc... This adherence to tight coupling leads to some extensive measures such as using the same mounting material machined as one piece from bearing to tonearm base to ensure if any possible vibration generated they would vibrate in unison.
Thank you directdriver. Are you also of the opinion that in a good direct drive table that motor vibration is not an issue of concern - and that external vibrations are the main concern? That opinion is has been stated by several users on this thread.
One reason I continue inquiring is because of some communications I've received on a different thread. For example:
"Direct drive has this challenge as you note, the motor shaft is coupled to the platter directly, hence the name. Most of these systems mount the motor to the plinth and then the tonearm to the plinth without a third brace or casting to couple them more rigidly. The idea being that the plinth should be designed to be rigid enough to keep alignment and also to provide damping. Belt drives, when properly isolated, do not require damping and it is actually another benefit of that system since damping effects playback. In a DD system where it is unavoidable to have some coupling of vibrations, creating a feedback loop with the stylus and record (platter), damping is often a topic of much design concern."
See in bold. It sure reads as if this contributor believes that direct drive motor resonances are worthy of some consideration. Either that or I've misconstrued his intent. I've sought clarification.
But you can imagine that for a newbie like me, when what appears to be inconsistent messages are offered by folks who seem to be experts, confusion quickly ensues.
Last edited:
Thank you again for your input. I think the shorter version of this is that you recommend I use an established material(s) and focus on quality of build and then experiment next with a variety of setup variables. Then once I've acquired some first-hand experience and knowledge of my own, I can start to expand. And that this makes sense because in the big scheme of things, the plinth design is only one of many variables and not the biggest area of concern.
Is that about right?
The only thing I'd say from here is, as I wrote to directdriver, that I've received some seemingly contrary input from someone who seems to be an experienced user on a different site:
"Direct drive has this challenge as you note, the motor shaft is coupled to the platter directly, hence the name. Most of these systems mount the motor to the plinth and then the tonearm to the plinth without a third brace or casting to couple them more rigidly. The idea being that the plinth should be designed to be rigid enough to keep alignment and also to provide damping. Belt drives, when properly isolated, do not require damping and it is actually another benefit of that system since damping effects playback. In a DD system where it is unavoidable to have some coupling of vibrations, creating a feedback loop with the stylus and record (platter), damping is often a topic of much design concern."
Which ends up sounding like a contradiction to what you're saying. As a newbie, that's really confusing. Which is why I've continued to seek clarification. (On both sites)
But I won't press this further with you. And I appreciate your points on eliminating below-audible speaker noise and focusing on turntable placement. But I'd like to ask another question in regards to protecting the platter/tonearm system from external speaker vibrations, which is... how important is plinth design in this regard?
Thank you for bearing with me.
It's even "worse" than the motor shaft being directly coupled to the platter, the motor rotor is built into the platter.
The problem with this thinking is it equates motor with something that creates vibration and noise. For a device that runs 300 RPM or higher, that's generally true, they're not perfectly balanced and make vibration, and pains are taken to isolate a belt drive motor from the plinth and platter.
In a direct drive, platter rotation is caused by the stator creating a slowly varying magnetic field pushing on the magnets in the rotor, creating virtually no noise. I dare say the biggest source of vibration noise in either a direct or belt drive TT is the platter bearing.
That's a sensible observation.
Since in a DD system, the 'only thing' physically connected is the rotating spindle, and the sleeve it sits in.
There are a lot of 'overthinkers' that discuss ways to minimise noise of such things.
I would assume that many have simply purchased 'less than perfectly machined' or faulty turntables, and/or the manufacturers just don't give a crap about this part of the turntable - as they once did.
I know that in the golden era of turntables, somewhere in the 1970's/80's, the platter bearings were held to strict tolerences, as were the motors themselves.
United Audio/Dual for instance, advertised that the motor shafts in their idler-drive units were "micro polished" to strict specifications to eliminate motor-born noise.
All of the turntables that I've had to service on my repair bench at the shop, which amount to thousands, I've had the chance to see, handle, and determine manufacturing quality, and compare against other models/brands.
You just get to know after a while who's 'good' and who's mediocre.
You'd be surprised at some of those 'high end' models made with obvious flaws, and some of those 'budget' machines high quality platter bearing assemblies.
The same thing goes for the "wow & flutter" specs, because it's not always price point tier levels that determine that specification.
My own DD Kenwood, made about 1987, surprises me with excellent specifications, and it's not some glamorous-to-the-eye machine.
With 0.025% wow/flutter figures, it far surpsasses some of the current 'high end' stock sold today.
And its platter bearing is dead silent as well, without the need to "upgrade" with those ceramic/jewel ball bearings that some manufacturers sell to improve rumble figures.
If they built the darn thing right in the first place, for the price they're asking, none of these 'improvements' would ever be needed.
Methinks that it's all about some form of continuing revenue, leading the consumer to spend more after the fact - a sneaky, shady way of doing business.
This also happens with other products of course.
As for rumble spcifications - when you're dealing with a rotating record with a stylus in its grooves, there's an inherent about of background 'noise' that naturally happens due to the vinyl's quality.
This low frequency (sub sonic) component is not music, nor is it worthy to even keep around.
I mentioned earlier in this thread about solutions to help rectify it, along with the beneficial results it produces.
Thank you again for your input ' 
'
I think the shorter version of this is that you recommend I use an established material(s) ' Yes '
and focus on quality of build and then experiment next with a variety of setup variables. ' focus on the quality of the set up as you are in a very good place with your build materials list '.
Then once I've acquired some first-hand experience and knowledge of my own, I can start to expand. ' The Vinyl Front End Experience can be endless in investigation and learning, the place where one stops is belonging to the individual, 30 Years in I am still participating in learning and meeting other enthusiasts '.
And that this makes sense because in the big scheme of things, the plinth design is only one of many variables and not the biggest area of concern.
' Correct '
Is that about right? ' A very good place to join the journey '.
To my Perception one of the most impressive/memorable TT's I have experienced to date, is a used on another system.
It is mounted on a TT Shelf that is Fastened into the Wall.
There is a few tiers for the Sub Plinth with a few different footers in use.
The DDTT Plinth is 32mm Panzerholz and it is produced using the design philosophy that I believe 'directdriver' is referring to,
where the Drive of the TT and Tonearm are mechanically coupled in the same Plinth Material.
I have been informed of the extremely tight tolerances produced for the positioning of the Components and their fastenings.
I have put the 'Feet of Silence' under this TT's Plinth with no real change being perceived.
That was one of the few TT's not to seem to show a immediate change for the better.
'I think the shorter version of this is that you recommend I use an established material(s) ' Yes '
and focus on quality of build and then experiment next with a variety of setup variables. ' focus on the quality of the set up as you are in a very good place with your build materials list '.
Then once I've acquired some first-hand experience and knowledge of my own, I can start to expand. ' The Vinyl Front End Experience can be endless in investigation and learning, the place where one stops is belonging to the individual, 30 Years in I am still participating in learning and meeting other enthusiasts '.
And that this makes sense because in the big scheme of things, the plinth design is only one of many variables and not the biggest area of concern.
' Correct '
Is that about right? ' A very good place to join the journey '.
To my Perception one of the most impressive/memorable TT's I have experienced to date, is a used on another system.
It is mounted on a TT Shelf that is Fastened into the Wall.
There is a few tiers for the Sub Plinth with a few different footers in use.
The DDTT Plinth is 32mm Panzerholz and it is produced using the design philosophy that I believe 'directdriver' is referring to,
where the Drive of the TT and Tonearm are mechanically coupled in the same Plinth Material.
I have been informed of the extremely tight tolerances produced for the positioning of the Components and their fastenings.
I have put the 'Feet of Silence' under this TT's Plinth with no real change being perceived.
That was one of the few TT's not to seem to show a immediate change for the better.
I've been pondering the same question here, trying to design a plinth for an sp-15 that will be (within reason) as good as I can make with the tools and materials I have and the energy/time that I have to invest in the project.
My biggest concern is separating out footfalls from getting amplified, since my room does not have particularly rigid floors. the smart thing to do would be reinforce the floor from underneath, but that's not happening any time soon.
Regarding using resin/bentonite, don't count that out. It doesn't have to be touched by your woodworking tools. I imagine you can build a box to use as a form out of the wood of your choice, and then cast the resin mix directly into the form and leave it there. nothing to machine, no worries. I'm tempted to try that in my design, but probably won't be bothered with this particular iteration.
for what it's worth, I'm going to go ahead and make mine using alternating layers of hardboard and MDF, partly for ease of manufacture, partly because I already have the materials I need, and partly for looks. Sandwiched together in layers and finished with oil/urethane, the hardboard gets a chocolaty brown color, while the MDF will stay a nice golden brown. I'm vacillating between making this a solid chunk of material with hole for the motor board and tone arm, and having the solid chunk hollowed out in spots that can be filled with newplast/Plasticine/resin with bentonite, sand, lead, or whatever else strikes my fancy. Another option would be to sandwich in pieces of particle board in those voids.
I have the benefit of a CNC router at my disposal, so my design is going to follow somewhat within the capabilities of the machine to make things easier for me.
My biggest concern is separating out footfalls from getting amplified, since my room does not have particularly rigid floors. the smart thing to do would be reinforce the floor from underneath, but that's not happening any time soon.
Regarding using resin/bentonite, don't count that out. It doesn't have to be touched by your woodworking tools. I imagine you can build a box to use as a form out of the wood of your choice, and then cast the resin mix directly into the form and leave it there. nothing to machine, no worries. I'm tempted to try that in my design, but probably won't be bothered with this particular iteration.
for what it's worth, I'm going to go ahead and make mine using alternating layers of hardboard and MDF, partly for ease of manufacture, partly because I already have the materials I need, and partly for looks. Sandwiched together in layers and finished with oil/urethane, the hardboard gets a chocolaty brown color, while the MDF will stay a nice golden brown. I'm vacillating between making this a solid chunk of material with hole for the motor board and tone arm, and having the solid chunk hollowed out in spots that can be filled with newplast/Plasticine/resin with bentonite, sand, lead, or whatever else strikes my fancy. Another option would be to sandwich in pieces of particle board in those voids.
I have the benefit of a CNC router at my disposal, so my design is going to follow somewhat within the capabilities of the machine to make things easier for me.
Here some pictures of the basic design. there will be a board mounted for the tone arm in the semi-rectangular hole on the right. I'm going to need some kind of isolation feet with this, so will either do sprung rubber feet of some sort, or maybe make some cones?
I'm curious to see what y'all have come up with, or been thinking about.
I really don't think there's any sadness in making a plinth from particle board. other than being moisture sensitive, it's supposed to be pretty good stuff. of course you'll need to fill and paint it, or veneer it to make it look nice. seal it well to prevent attack from moisture.
I'm curious to see what y'all have come up with, or been thinking about.
I really don't think there's any sadness in making a plinth from particle board. other than being moisture sensitive, it's supposed to be pretty good stuff. of course you'll need to fill and paint it, or veneer it to make it look nice. seal it well to prevent attack from moisture.
Attachments
the above are quick renderings from my 3D modeling program, but finished product will look similar.
Regarding those "cones" you speak of.....
If they're pliable/rubberish, they may be OK.
However, if you're speaking about those "high end" pointed metal cones sold all over and advertized as "special" - they're just a marketing ploy with no isolation properties at all.
And how could they be? - they're rigid metal!
I have always wondered about whether such things actually work. I think the theory is/was that I was told is that because they’ve got such a small contact point that they minimize vibrations transmitted into the base/plinth, but I’m a rank amateur physicist at best, and can’t evaluate whether this is true without trying it out.
As a diy type, I have the ability to make my own unpolished metal thingies (polishing can be a bit of a fool’s errand), and see if they work.
As a diy type, I have the ability to make my own unpolished metal thingies (polishing can be a bit of a fool’s errand), and see if they work.
Any Material used in a Plinth that is not Stable in all environments will change as the Seasons Change and will Expand or Contract as a result of Moisture in the Air or Heat Exchanges.
Hence on of the reasons Panzerholz is also selected more commonly is that is non reactive to a environment it is placed in for use as a plinth.
As a material, if the Tonearm is attached to the Plinth without a Mounting Plate, the Dimension set for the Platter Spindle to the Tonearms Pillar Axis will not vary through out the seasonal changes.
The design will remain in a extreme tight tolerance and is very True to the Rigid Philosophy for TT's, which seems to be the trend for DD's and Idler Drives.
Newplast can also be applied to the MDF to increase the value of it in relation to its damping properties.
PolyB' Resin measures very close to P'holz for the damping factor.
A wall mounted TT Shelf might be a Shortcut to overcoming issues with a bouncy floor.
Do take the time to try out a few sub plinth combinations of materials, there is a lot to be achieved by doing this.
Hence on of the reasons Panzerholz is also selected more commonly is that is non reactive to a environment it is placed in for use as a plinth.
As a material, if the Tonearm is attached to the Plinth without a Mounting Plate, the Dimension set for the Platter Spindle to the Tonearms Pillar Axis will not vary through out the seasonal changes.
The design will remain in a extreme tight tolerance and is very True to the Rigid Philosophy for TT's, which seems to be the trend for DD's and Idler Drives.
Newplast can also be applied to the MDF to increase the value of it in relation to its damping properties.
PolyB' Resin measures very close to P'holz for the damping factor.
A wall mounted TT Shelf might be a Shortcut to overcoming issues with a bouncy floor.
Do take the time to try out a few sub plinth combinations of materials, there is a lot to be achieved by doing this.
Ok, think about this for a moment.......
"you were told" - by whom? - an online statement? - a friend said? - Advertizing? - hearsay somewhere?
Now, not knowing physics, (which I do), think..... how can something solid, rigid, in direct contact with something else rigid, be of use to stem vibrations traveling from one thing to another?
There has to be a pliable, flexible material involved, to hinder abrupt movements.
Like a shock absorber in a car's wheel for instance.
It reduces vibrations in the passenger compartment.
Try driving a car with its wheels rigidly attached to the car frame.
See where I'm getting?
Here's something else.....
A sylus in a record groove - yes, it's "pointy" like those "cones", but honestly, does it hinder vibrations of the modulated record groove? - if it did, then no sound would be able to be heard from a recording.
Last edited:
I see many marvels of engineering in turntable design. However, I don't see use made of obvious damping materials such as sand. Another is bituminous compounds. There is one arm design that is sand filled but, has this been used for plinths?
Having studied vibration separate from turntable uses, any solid in contact with another solid, transmits vibration. This includes foam, although foam in compression dampens other materials. Control of vibration needs an approach using amorphous materials. The challenge is to make it cosmetically acceptable.
Having studied vibration separate from turntable uses, any solid in contact with another solid, transmits vibration. This includes foam, although foam in compression dampens other materials. Control of vibration needs an approach using amorphous materials. The challenge is to make it cosmetically acceptable.