Best surface, Marble, slate, cutting board???

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Re: Best surface, Marble, slate, cutting board???

Post by cats squirrel » 02 Dec 2019 15:23

Woodbrains wrote:
01 Dec 2019 18:22
Hello,

There are good reasons for making thin plinths. They are cheap!
not necessarily so. A plinth I am making for a Lenco-based PTP6 consists of two different honeycomb structures, one of which is used in aircraft fuselages. They will be filled or partly filled to provide enough damping and the correct amount of mechanical impedance to match that of the 4mm thick steel parts of the PTP6. It will NOT be cheap, but it WON'T be thick.
Rega are using very low density material for their higher end tables. The reason being, if there is less material for vibrations to propagate through, there will be less energy to transfer etc. I agree, it is a fine application of physics and it apparently works well if the reviews of these products are reliable.
Vibrations do not propagate through, at least not through thin plates, but as the thickness increases and frequencies increase, the vibrations will turn into sideways displacements, and shearing will develop. A thin plate does not suffer from this, only thick pates (plinths).
However, mass loading also works from the other point of view. The energy of the vibrations that we are talking about are tiny. If they haven't enough oomph to get a massive body vibrating they won't give too much trouble. Plus a lot of mass has many particles to lose energy as heat.
Yes, the displacements are small, but relative to how much the stylus is moved by the record groove, it is in the same ball park. And damping is an intrinsic property, it does not rely on amount of material. Think density (another intrinsic property), it doesn't matter if you measure a 10mm cube of steel, or a whole ship full of steel, the answer is the same. Same with damping.
It is all very well talking about 'plates' having fundamental frequencies that with vibrate in harmony with external sources of vibration. Well that is true, but, and even counting all the harmonics as well, we are talking of a very narrow band of frequencies that will cause trouble.
What you are alluding to is called modal density, that is, the number of resonance frequencies per unit frequency. And yes, it is important. Thin materials will have a lower fundamental resonance frequency, so the related harmonic (and anharmonic) frequencies will be relative to that. Thicker plinths (of the same perimeter as the thin one) will have higher resonance frequencies, and maybe in the region where applied damping is more effective.

However, I have learnt over the last dozen or so years I've been working on material properties that everything is a compromise, and one has to decide which of the properties is more important to optimize. So comparing an 18mm thick plywood plinth, compared to a 100mm thick one, modal density is higher, fundamental resonance frequency is much lower, critical frequency much higher, damping factor a touch higher (but still very low!) and flexural rigidity much much lower. But the overriding parameter which is the most informative is the losses for the two plinths. The thin plinth losses are between 14dB and 26dB, from 20Hz to above 1kHz, whereas the thick plinth only manages 6 - 12 dB over the same range. This is mainly down to the much higher stiffness of the thick plinth. If the damping factor of the material was 0.4 instead of 0.04, then losses would be from 30 to 36dB! showing the importance of high damping factors.
Multi layering of dissimilar materials does have an effect on reducing vibrations transferring at the fundamental of one through a junction to a fundamental of another. Just the same as sound moving from air to a wall back to air. If it didn't lose energy at each junction, playing your music in one room would sound just as loud in the next. It clearly does not.
Can't agree. As I have already stated (above), if materials are just placed one on top of another (not fixed in position) then mechanical impedance comes into play. If they are glued/screwed together, then a new material is made, which will have just one set of parameters. All the layers will move together, one set of vibrations. I have measured this over and over again! Your analogy doesn't work.
There are many ways to skin a cat. #-o But making massy plinths with lovely wood veneer finishes is 10 times more expensive than a polyurethane sandwich with a rather dreadful appearance, as per Rega. Cost has more to do with it than physics.
yes, costs have a lot to do with it, as has appearance and making a plinth fit for purpose!
By the way. I have just made a massy plinthed table from a Rega Planar 2. I'm using the original AC motor, and it is the most eerily quiet table I have (not) heard. I'm willing to bet my humble Rega is at least as quiet at any higher end Rega with the new motors and neo PS. And it looks 10 times more beautiful, belying its humble origins. It would cost a lot to produce my table, though and not production line semi skilled operative produceable.
and just imagine what a thin plinth made of a damping material would have done for you! But if you are satisfied with it, I'm happy for you. :D

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Re: Best surface, Marble, slate, cutting board???

Post by Direct driver » 02 Dec 2019 15:34

goatbreath wrote:
15 Nov 2019 22:09
Before anyone condemns this idea,actually try this,the reason I do it is because it works..
Any theories I came up with is why I think it may be working..
I just know I always end up with a variation on this arrangement..

I have found and still needle on records,then advancing the volume control confirms it,as does the better tracking and all that goes along with that... A Heavy Slab of dense piece of mass like concrete or marble can stop vibrations in the room getting into the turntable..
This is of course a good thing..

BUT as far as the Turntable sitting on something with higher mass than it..
This creates a closed loop as the vibrations have nowhere to go as they hit a denser material,
so they just go back into the turtable,which gets back to the needle....
Again try the still needle on the record test,and sowly advance the volume control..
Or listen to how much less confused the sound on the record is..
That sounds subjective,but acoustic feedback is an objective thing..
In other words the heavy slab etc acts as a barrier yet again..Why wouldn't it..??

Solution..A not too heavy piece of wood on sorbothane feet on top of the Mass Barrier..
Even rubber feet still work..
Even on my Wallshelf,the actual shelf is glass..
It sounds better using a secondary piece of lightish rigid wood on rubber or sorbothane feet....
The feet decouple the lighter board from the denser material..
The vibration travels out of the turntable into the lighter board..
Why too light a board shouldn't be used.
Although the Ikea Lack Idea,that is really light..
I have found something a big more substantial works a bit better..

I know it isn't the usual conventional view that sells overpriced isolation products..
Again,try it before you condemn it.. :) :) :)


Pine or Spruce is good,something fast growing,Contiboard seems to work not bad too..
It seems to be lossy,,I haven't figured out why as it doesn't have straight grain for the vibration to travel along..
Why I think Pine,Spruce etc..May be best of all..
MDF is a bit too dense,a thick bit of MDF is more of a barrier. than able to drain vibrations...

Think about an acoustic guitar,the soundboard is usually made from spruce or Cedar,
a fast growing therefore broader grained wood..this means vibration travels in it easily..
The back and sides in a quality acoustic are usually a slower growing denser wood..Rosewood or Mahogany etc..
These denser woods mean that the vibration has nowhere to go,meaning the vibrations will travel back along the soundboard again, guitar will hopefully project better,plus actually be louder.
If you just used the Spruce top itself,the vibration would travel straight out of it,
so by sitting a Turntable on a rigid enough surface the vibration travels into the board and is drained off..
you obviously need a thicker board than a flexible guitar top..
For me, two of those 8x16x3 concrete slabs from Lowes or Home Depot can work just fine. Or the 16x16 pavers, around the same thickness. The turntable sits right on top of them with it's own rubber feet doing the rest. If one want's to get fancy, you can use JB Weld to glue the former together and for either solution use any kind of vinyl spackle to make them smooth as glass and then paint to taste or even apply wood veneer if one is so inclined. There is some amazing clear coat "in a spray can" material available nowadays. Get the one where you have to push the pin at the bottom of the can to mix the two materials before spraying.

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Re: Best surface, Marble, slate, cutting board???

Post by cats squirrel » 02 Dec 2019 15:53

yep, make it look good, and it will sound good! :roll:

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Re: Best surface, Marble, slate, cutting board???

Post by Mr Pig » 02 Dec 2019 16:24

cats squirrel wrote:
02 Dec 2019 15:23
However, I have learnt over the last dozen or so years I've been working on material properties that everything is a compromise, and one has to decide which of the properties is more important to optimize.
Exactly. There is no such thing as the correct solution, only the result you like.

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Re: Best surface, Marble, slate, cutting board???

Post by cats squirrel » 02 Dec 2019 17:06

I think there are acceptable solutions. BUT, trying to get 'the sound you like' is like shinning a coloured light on a masterpiece painting.

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Re: Best surface, Marble, slate, cutting board???

Post by Mr Pig » 02 Dec 2019 18:00

cats squirrel wrote:
02 Dec 2019 17:06
..BUT, trying to get 'the sound you like' is like shinning a coloured light on a masterpiece painting.
Not really. Firstly, with vinyl you don't know what the record is supposed to sound like. All of the equipment used to produce it and the playback systems used by the recording engineers to asses their work were all also coloured. To reproduce the record as the original artists heard it you would have to replicate the coloured equipment they had!

If you play a record on a modern low colouration turntable the only thing you can be sure about is that what you are hearing is nothing like the sound listeners heard a few decades ago.

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Re: Best surface, Marble, slate, cutting board???

Post by Alex66 » 02 Dec 2019 18:03

This I find somewhat interesting, I did years ago mess around with different surfaces to place a turntable on, one low mass on a metal wall mount the other heavy materials, wood, granite and MDF on a sand bed. My ears told me a Pink Triangle sounded superb on the wall but lost a lot on the high mass platform, the two other tables I tried a home made solid plinth and a Garrard 401 sounded more open the other way round and mass loading seemed to work. I would be wary of gluing plates together as the glue itself will in many cases make it easier for two surfaces to move along the left right plane, better to make them rough and create friction in that plane. If I was doing it know I would properly read up about the materials, how they dissipate energy, what happens when say slate and oak ate placed together and most importantly what is the nature of the 'vibration' energy needs to be stopped and moved away. The previous experiments were on a hunch and gave me some understanding of the complexity involved, you could very well improve one function but cause other issues going down one path. Is anyone here experimenting with materials for TT plinths and or platforms, I would be interested in their findings.

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Re: Best surface, Marble, slate, cutting board???

Post by cats squirrel » 02 Dec 2019 18:07

Mr Pig wrote:
02 Dec 2019 18:00
cats squirrel wrote:
02 Dec 2019 17:06
..BUT, trying to get 'the sound you like' is like shinning a coloured light on a masterpiece painting.
Not really. Firstly, with vinyl you don't know what the record is supposed to sound like. All of the equipment used to produce it and the playback systems used by the recording engineers to asses their work were all also coloured. To reproduce the record as the original artists heard it you would have to replicate the coloured equipment they had!

If you play a record on a modern low colouration turntable the only thing you can be sure about is that what you are hearing is nothing like the sound listeners heard a few decades ago.
might as well give up, then... bummer

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Re: Best surface, Marble, slate, cutting board???

Post by cats squirrel » 02 Dec 2019 18:08

Alex66 wrote:
02 Dec 2019 18:03
This I find somewhat interesting, I did years ago mess around with different surfaces to place a turntable on, one low mass on a metal wall mount the other heavy materials, wood, granite and MDF on a sand bed. My ears told me a Pink Triangle sounded superb on the wall but lost a lot on the high mass platform, the two other tables I tried a home made solid plinth and a Garrard 401 sounded more open the other way round and mass loading seemed to work. I would be wary of gluing plates together as the glue itself will in many cases make it easier for two surfaces to move along the left right plane, better to make them rough and create friction in that plane. If I was doing it know I would properly read up about the materials, how they dissipate energy, what happens when say slate and oak ate placed together and most importantly what is the nature of the 'vibration' energy needs to be stopped and moved away. The previous experiments were on a hunch and gave me some understanding of the complexity involved, you could very well improve one function but cause other issues going down one path. Is anyone here experimenting with materials for TT plinths and or platforms, I would be interested in their findings.
yes I have, for the last 12 or so years. Most of what I understand is on here. :D

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Re: Best surface, Marble, slate, cutting board???

Post by Woodbrains » 02 Dec 2019 18:33

cats squirrel wrote:
02 Dec 2019 15:23
Woodbrains wrote:
01 Dec 2019 18:22
Hello,

There are good reasons for making thin plinths. They are cheap!
not necessarily so. A plinth I am making for a Lenco-based PTP6 consists of two different honeycomb structures, one of which is used in aircraft fuselages. They will be filled or partly filled to provide enough damping and the correct amount of mechanical impedance to match that of the 4mm thick steel parts of the PTP6. It will NOT be cheap, but it WON'T be thick.
Rega are using very low density material for their higher end tables. The reason being, if there is less material for vibrations to propagate through, there will be less energy to transfer etc. I agree, it is a fine application of physics and it apparently works well if the reviews of these products are reliable.
Vibrations do not propagate through, at least not through thin plates, but as the thickness increases and frequencies increase, the vibrations will turn into sideways displacements, and shearing will develop. A thin plate does not suffer from this, only thick pates (plinths).
However, mass loading also works from the other point of view. The energy of the vibrations that we are talking about are tiny. If they haven't enough oomph to get a massive body vibrating they won't give too much trouble. Plus a lot of mass has many particles to lose energy as heat.
Yes, the displacements are small, but relative to how much the stylus is moved by the record groove, it is in the same ball park. And damping is an intrinsic property, it does not rely on amount of material. Think density (another intrinsic property), it doesn't matter if you measure a 10mm cube of steel, or a whole ship full of steel, the answer is the same. Same with damping.
It is all very well talking about 'plates' having fundamental frequencies that with vibrate in harmony with external sources of vibration. Well that is true, but, and even counting all the harmonics as well, we are talking of a very narrow band of frequencies that will cause trouble.
What you are alluding to is called modal density, that is, the number of resonance frequencies per unit frequency. And yes, it is important. Thin materials will have a lower fundamental resonance frequency, so the related harmonic (and anharmonic) frequencies will be relative to that. Thicker plinths (of the same perimeter as the thin one) will have higher resonance frequencies, and maybe in the region where applied damping is more effective.

However, I have learnt over the last dozen or so years I've been working on material properties that everything is a compromise, and one has to decide which of the properties is more important to optimize. So comparing an 18mm thick plywood plinth, compared to a 100mm thick one, modal density is higher, fundamental resonance frequency is much lower, critical frequency much higher, damping factor a touch higher (but still very low!) and flexural rigidity much much lower. But the overriding parameter which is the most informative is the losses for the two plinths. The thin plinth losses are between 14dB and 26dB, from 20Hz to above 1kHz, whereas the thick plinth only manages 6 - 12 dB over the same range. This is mainly down to the much higher stiffness of the thick plinth. If the damping factor of the material was 0.4 instead of 0.04, then losses would be from 30 to 36dB! showing the importance of high damping factors.
Multi layering of dissimilar materials does have an effect on reducing vibrations transferring at the fundamental of one through a junction to a fundamental of another. Just the same as sound moving from air to a wall back to air. If it didn't lose energy at each junction, playing your music in one room would sound just as loud in the next. It clearly does not.
Can't agree. As I have already stated (above), if materials are just placed one on top of another (not fixed in position) then mechanical impedance comes into play. If they are glued/screwed together, then a new material is made, which will have just one set of parameters. All the layers will move together, one set of vibrations. I have measured this over and over again! Your analogy doesn't work.
There are many ways to skin a cat. #-o But making massy plinths with lovely wood veneer finishes is 10 times more expensive than a polyurethane sandwich with a rather dreadful appearance, as per Rega. Cost has more to do with it than physics.
yes, costs have a lot to do with it, as has appearance and making a plinth fit for purpose!
By the way. I have just made a massy plinthed table from a Rega Planar 2. I'm using the original AC motor, and it is the most eerily quiet table I have (not) heard. I'm willing to bet my humble Rega is at least as quiet at any higher end Rega with the new motors and neo PS. And it looks 10 times more beautiful, belying its humble origins. It would cost a lot to produce my table, though and not production line semi skilled operative produceable.
and just imagine what a thin plinth made of a damping material would have done for you! But if you are satisfied with it, I'm happy for you. :D
Hello,

I'm not disputing that a thin plinth, made from some super damping material would not work, I said that rega's low mass solution was based on good physics. However, that approach would not have worked for reducing the vibrations and noise of the Premotec AC motor. My massy plinth absolutely does in this case.

Glued up materials forming a composite certainly does yeild properties that neither material has on its own. Simply stacking does not make a composite, a mechanical bond is necessary. It is a different approach and can work if correctly applied. Rega's foam filled sandwich is a composite, and a light weight, thin one, after all. I have used .5mm stainless steel sheet, top and bottom of 9mm birch plywood to make an arm board. It must been glued, to a) stiffen and b) eliminate the ringing of the steel. The resultant 10 mm board is stiffer and deader than any other material of similar thickness that I can find or make.

Also, care must been taken not to dampen the life out of the music and make it sound exactly likes a CD!

Mike.

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Re: Best surface, Marble, slate, cutting board???

Post by Direct driver » 02 Dec 2019 19:42

cats squirrel wrote:
02 Dec 2019 15:53
yep, make it look good, and it will sound good! :roll:
Actually, what I meant was that if you ALSO want it to look good you can improve the looks. Plain concrete is not really all that attractive in most home decor's, especially within the concept of "wife friendly". :)

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Re: Best surface, Marble, slate, cutting board???

Post by Direct driver » 02 Dec 2019 19:47

cats squirrel wrote:
02 Dec 2019 18:07
Mr Pig wrote:
02 Dec 2019 18:00
cats squirrel wrote:
02 Dec 2019 17:06
..BUT, trying to get 'the sound you like' is like shinning a coloured light on a masterpiece painting.
Not really. Firstly, with vinyl you don't know what the record is supposed to sound like. All of the equipment used to produce it and the playback systems used by the recording engineers to asses their work were all also coloured. To reproduce the record as the original artists heard it you would have to replicate the coloured equipment they had!

If you play a record on a modern low colouration turntable the only thing you can be sure about is that what you are hearing is nothing like the sound listeners heard a few decades ago.
might as well give up, then... bummer
I have old and new turntables. They all sound pretty much the same with the same cartridge. They are all quiet, so the only real difference in my turntables is the tonearm. One is low compliance and the others are all high compliance. But they still all pretty much sound the same with the same cartridge.

Then again, I wear hearing aids sometimes (for meetings), so who am I to tell. :)

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Re: Best surface, Marble, slate, cutting board???

Post by Mr Pig » 02 Dec 2019 20:09

Direct driver wrote:
02 Dec 2019 19:47
I have old and new turntables. They all sound pretty much the same with the same cartridge.
I've never had two turntables that sounded the same. Even two near identical LP12s with the same arm and cart on them did not sound the same.

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Re: Best surface, Marble, slate, cutting board???

Post by Direct driver » 02 Dec 2019 20:22

Mr Pig wrote:
02 Dec 2019 20:09
Direct driver wrote:
02 Dec 2019 19:47
I have old and new turntables. They all sound pretty much the same with the same cartridge.
I've never had two turntables that sounded the same. Even two near identical LP12s with the same arm and cart on them did not sound the same.
That's why I said "pretty much". I've never recorded them and then compared the recordings, and it's been decades since I would A/B my stuff.

I consider the difference in sound from "high quality" turntables to be small enough, compared to the differences presented by cartridges and speakers, to not really matter to me. Heck, the difference between my AT15SA cartridge and the green cheapie AT cartridge that came on my ATLP120 to sound close enough that I'd be happy with either, even though I can hear the difference pretty easily.

I'm more concerned about the quality of the scotch I'm drinking and cigars I'm smoking while listening to the different records. I've been at this a very long time and my system just sort of reached a "good enough" point for me about 15 years ago and I can now just enjoy it without worrying about eeking out the last scintilla of "quality" for the dollar level. I enjoy my system and the music now much more than the days when I was learning all this stuff and trying to get it "just right", which turns out to have been not possible in the real world. At least, not for me.

I do enjoy comparing speakers, though. They make a HUGE difference. Cartridges make a "big" difference.

Oh, and I'm thinking about replacing some capacitors in my amplifiers and pre-amps. For the record, the ATLP120 is NOT my main turntable. I got it for some special needs.

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Re: Best surface, Marble, slate, cutting board???

Post by cats squirrel » 02 Dec 2019 20:42

Woodbrains wrote:
02 Dec 2019 18:33


Hello,

I'm not disputing that a thin plinth, made from some super damping material would not work, I said that rega's low mass solution was based on good physics. However, that approach would not have worked for reducing the vibrations and noise of the Premotec AC motor. My massy plinth absolutely does in this case.

Glued up materials forming a composite certainly does yeild properties that neither material has on its own. Simply stacking does not make a composite, a mechanical bond is necessary. It is a different approach and can work if correctly applied. Rega's foam filled sandwich is a composite, and a light weight, thin one, after all. I have used .5mm stainless steel sheet, top and bottom of 9mm birch plywood to make an arm board. It must been glued, to a) stiffen and b) eliminate the ringing of the steel. The resultant 10 mm board is stiffer and deader than any other material of similar thickness that I can find or make.

Also, care must been taken not to dampen the life out of the music and make it sound exactly likes a CD!

Mike.
I can't say I agree with anything you have written, so I'll leave it there, and have a chuckle to myself. Thanks Mike. :wink: