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  #31  
Old 04-01-17, 05:35 AM
YNWOAN YNWOAN is online now
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Originally Posted by Helen Bach View Post
......and about a tenth that required.
How have you defined and calculated what is 'required'?
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  #32  
Old 04-01-17, 06:50 AM
Helen Bach Helen Bach is offline
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Originally Posted by YNWOAN View Post
How have you defined and calculated what is 'required'?
The idea is predicated on the assumption that it is important to reduce the amount of unwanted vibrations to a minimum. In the case of a turntable, this means reduction of the vibrations in the mechanicals of the tt, and any aerial and/or seismic intrusion. Any plinth (worthy of the name) must be able to cope with all these vibrations, reducing them to a level where they are not a problem.

As energy is said to be unable to be created or destroyed, the only only course of action is to turn vibrational energy into heat energy, by dissipation, or as we have come to call it, damping. Damping in this context can be defined as the exponential decay of vibrational energy, and although there are several ways of damping, frictional damping seems to be used the most.

So we use frictional damping to reduce the energy of the vibrations as quickly as possible, because that gives us the best chance of ensuring a 'clean signal', one that helps us with the fidelity of reproduction.

It can be shown that higher damping factor (DF) values are of the most benefit, but in reality, a value of 0.4 is a good one to aim for, as above this figure, there are diminishing returns. However, most materials used for audio structures (which need damping) fall far short of this 0.4 DF value, and most are less that 0.1. As an example, the OP mentioned Panzerholz, which has a DF of 0.6 - 0.9. By stark comparison, Corian has a DF of 0.044.
This means that a structure made of Corian would not be able to cope with vibrations at all well, and would allow these vibrations to continue to be a problem for some time (slate takes over a second to dissipate a single pulse, with a DF of 0.017, same as mdf !) whereas Panzerholz would dissipate the energy very quickly, not allowing those amplitudes to build, which is what happens with low DF materials.

HTH
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  #33  
Old 04-01-17, 07:02 AM
YNWOAN YNWOAN is online now
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Quote:
Originally Posted by Helen Bach View Post
Any plinth (worthy of the name) must be able to cope with all these vibrations, reducing them to a level where they are not a problem.
Do you believe that all vibration can be dealt (including seismic intrusion) with just by the material used to make the plinth from?

The damping factor of a construct can be significantly altered by the methods used to build the structure (plinth) as a whole.
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  #34  
Old 04-01-17, 07:04 AM
Julf Julf is offline
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Quote:
Originally Posted by YNWOAN View Post
The damping factor of a material can be significantly altered by the methods used to construct the structure (plinth) as a whole.
I thought the discussion was about materials, not construction?
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  #35  
Old 04-01-17, 08:03 AM
Helen Bach Helen Bach is offline
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Quote:
Originally Posted by YNWOAN View Post
Do you believe that all vibration can be dealt (including seismic intrusion) with just by the material used to make the plinth from?

The damping factor of a construct can be significantly altered by the methods used to build the structure (plinth) as a whole.
it is usual to talk about the damping factor of a material rather than a structure. Usually, a structure will contain many materials, each with their own DF, but with the possibility of modification by combining materials. If these materials are closely coupled (glued, welded) they form new materials, usually following (to the first approximation) the rule of mixtures. However, even structures which are bolted together can have extra damping conferred at the joints, and I have one turntable/plinth which does just that.

I don't believe we can ever deal with all the vibrations, but we don't need to, we only have to reduce the amplitudes of the vibrations to a level where they cause no problems. Most plinths/turntables don't.

I am thinking of a BBC white paper on loudspeaker design. On testing a design, they found that they could hear distortion. Further investigation showed where the distortion was, and what levels they had to be reduced to so as not to be a problem. Listening tests confirmed their measurements. This is a good exemplar where listening and measurements compliment each other.
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  #36  
Old 04-01-17, 09:26 AM
YNWOAN YNWOAN is online now
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With respect, I know all of that. In both your responses you state a whole load of related theory I already know but don't actually answer the question. Let me put it directly; what material* do you think will offer sufficient damping to be useful for seismic intrusion (this is something you claimed earlier).

* By material I don't mean laminate or constrained layer structure. I have used a constrained layer (many confuse this with laminating) construct of aluminium and viscoelastic bonding and this has produced a structure that is both stiff and very well damped.

For what it's worth, high self damping is not my primary choice for the material chosen to construct my plinth. IMO, as with many areas of design, to claim one material is inherently better than another is to oversimplify the issues.
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  #37  
Old 04-01-17, 01:14 PM
John R John R is offline
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Quote:
Originally Posted by YNWOAN View Post

* I have used a constrained layer (many confuse this with laminating) construct of aluminium and viscoelastic bonding and this has produced a structure that is both stiff and very well damped.

F
I wonder if that is why the Rubikon was so successful?
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  #38  
Old 05-01-17, 02:39 AM
flatpopely flatpopely is online now
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Thanks for the compliment John, yes it was successful for a number of reasons.

Mark spent literally hundreds of man hours designing a truly different sub chassis not copying from anyone's ideas. The resulting sound quality was, and is, in our opinion, the equal of the Keel. The design was of such a high standard that once complete we did not need to constantly evolve and therefore leave customers with a MKI wishing they had a MKII, III, IV etc.

I worked very hard at ensuring the manufacturing/finish and packing was the equal of Linn and I believe we achieved that. This was necessary as we decided early on to sell through Linn dealers; and they, and their customers, demand excellence in this area.

We were the very first of a new breed of sub chassis for the LP12 that was aimed to be sold via Linn's dealer network - we are very proud that we gained acceptance into this network. Whatever ones views about selling via the dealer channel AudioFlat gained acceptance into it. For Peter at Cymbiosis to dedicate so much time was a mark of how much work we had put into the product!

Our professional approach to the RubiKon gained us support from Linn and Naim; I'm not prepared to say what that was but suffice to say it's nice to be recognized for being professional at what one does, especially from two of the biggest names in Hi-Fi. I have a nice relationship with people at Linn and post on their Forum from time to time.

The product got a favorable mention from Paul Messenger and he used a RubiKon in his own LP12 for a while.

We stopped manufacture of it for two reasons:-
1. Our supplier was unable to get the constancy we required.
2. Mark and I have full time jobs and the man hours required to deal with ongoing manufacturing issues meant we had to call time.

Actually the timing proved to be good as Linn had just released the 'Kore'. At the time 700 represented amazing vfm and with the support and backup from Linn via its dealers it remains an extremely compelling option at the sub 1k chassis point.

The good news is that Mark and I are still friends in spite of all the 'business' difficulties we went through, and believe me it wasn't easy!
There are still 20+ people out there enjoying the RubiKon, they are very lucky as it's a superb chassis for the LP12, designed from first principals to sound better than anything else using sound engineering, not finger in the wind stuff.
We still have all the CAD files so who knows one day we may make them again!
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  #39  
Old 05-01-17, 03:17 AM
John R John R is offline
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I'm glad for you.

Interestingly our Sole chassis was commented upon by Paul M when I met him and discussed the philosophy behind it a few years ago he also kcomented on it in an article published in HFC. Paul invited me over to his place in Herne Bay so he could review it, but to be honest things were and are going so well and with pressures in my previous days job, I just did not get around to it.

It's interesting to read your comment the various incarnations of Sole, which was as you know commented on a while ago by your design colleague. I am one who believes strongly in continuous improvement and am not so bold as to believe that I can never improve on an earlier design of my own or anyone else's for that matter. I believe that comes from having to do so in a quite stressful corporate manufacturing role, one in which I am now thankfully retired giving me more time to concentrate on things closer to home.


Regards to you.

John R.

BTW be good to see the Rubikon re enter the fray one day as I've always been one for offering more choice.

Last edited by John R; 05-01-17 at 04:32 AM. Reason: typo as usual
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  #40  
Old 05-01-17, 04:11 AM
YNWOAN YNWOAN is online now
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Quote:
Originally Posted by Julf View Post
I thought the discussion was about materials, not construction?
Well yes, but the two are inherently intertwined unless one only intends to use a single piece of said material. Also, my point (though not very clearly made) was really to say that considering the DF of a material in isolation is of little direct value.
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  #41  
Old 05-01-17, 11:27 AM
misterdog misterdog is offline
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I'm trying to get hold of some samples of this

http://www.richlite.com/what-is-richlite/#about
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  #42  
Old 05-01-17, 12:21 PM
YNWOAN YNWOAN is online now
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That looks really interesting .

It sounds a bit like Paxolin which is a resin impregnated and bonded paper structure.
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  #43  
Old 14-02-17, 12:01 AM
ChrisPa ChrisPa is offline
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Quote:
Originally Posted by orangeart View Post
Grimm use it for the baffle on thier super expensive monitors.
Which - Corian or panzerholz?
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  #44  
Old 14-02-17, 11:48 AM
Helen Bach Helen Bach is offline
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with a name like Grimm, I suggest it has to be Corian
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  #45  
Old 14-02-17, 12:21 PM
orangeart orangeart is offline
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Its Hi Macs
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