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Damping factors
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Bryan
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MessagePosté le: Jeu 4 Fév - 15:02 (2010)    Sujet du message: Damping factors Répondre en citant

I have been doing some damping factor measurements on materials that might be used for plinth construction.

François showed interest in the technique, and sent me some samples of the things he was working with, they came this morning.

Here are the results:

 aluminium laminate (ping pong table):  0.242

                                              panzer: 0.387

                           bentonite polyester:  0.399

These are materials with very good damping qualities. Anything with a damping factor above 0.1 is good, so all three materials look like winners.

If good sounding plinths are made from any of these materials, it suggests that good damping properties (and enough mass) do not rob the Lenco of life!


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MessagePosté le: Jeu 4 Fév - 15:27 (2010)    Sujet du message: Damping factors Répondre en citant

I told you Wink not only you btw Wink
I certainly lack academical knowledge, but thanks to my profession and training, I can say that I have developped some kind of feeling for vibes, good and bad ones Wink

Thanks for the test and mesurements bow


hats off

PS: Hats off to Rap who was the one to think about bento/poly compound hats off bow hats off bow


Dernière édition par François le Jeu 4 Fév - 15:41 (2010); édité 1 fois
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MessagePosté le: Jeu 4 Fév - 15:37 (2010)    Sujet du message: Re: damping factors Répondre en citant

Bryan a écrit:
I have been doing some damping factor measurements on materials that might be used for plinth construction.

François showed interest in the technique, and sent me some samples of the things he was working with, they came this morning.

Here are the results:

 aluminium laminate (ping pong table):  0.242

                                              panzer: 0.387

                           bentonite polyester:  0.399

These are materials with very good damping qualities. Anything with a damping factor above 0.1 is good, so all three materials look like winners.

If good sounding plinths are made from any of these materials, it suggests that good damping properties (and enough mass) do not rob the Lenco of life!




Une petite traduction:

"J'ai fait quelques mesures de facteur d'amortissement pour quelques matériaux qui pourraient être utilisés dans la construction d'un socle.
François ayant manifesté son intérêt, il m'a envoyé quelques échantillons que j'ai reçu ce matin.

Voici les résultats:
-Table de ping pong (sandwich d'aluminium et plastique): 0,242
-Panzerholz: 0,387
-Mélange polyester/bentonite: 0,399

Ces trois matériaux montrent un excellent facteur d'amortissement. Tout matériau avec un facteur supérieur à 0,1 est bon, par conséquent, ces trois matériaux ont tout l'air d'être des champions.

Si des socles sonnant bien ont été réalisés à partir de ces matériaux, cela tendrait à signifier, qu'un bon facteur d'amortissement allié à une masse suffisante n'ôtent pas la vivacité à une Lenco."


hats off
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MessagePosté le: Jeu 4 Fév - 16:21 (2010)    Sujet du message: Damping factors Répondre en citant

I believe what has been accomplished here is not to be taken lightly. It is my opinion that there has been a significant advancement in knowledge about the suitability of materials for plinth construction. I think we all deserve a pat on the back. This is a good day for hifi! and 'one in the eye' for those who choose to follow the 'accepted' path, blindly.

Having researched this subject for some time, I now understand a little more about the subject. It seems that for a panel (our plinth) there are three or four regions where vibrations are dealt with by different means.

Region 1: upper frequency defined by the fundamental resonance frequency (mode 1,1)  of the panel, dependant on the dimensions of the panel, Young's modulus and its density (and perhaps the Poisson ratio). This region is controlled by stiffness of the panel material.

Region 2: defined as the region between the fundamental resonance frequency and the critical frequency, itself determined by Young's modulus, mass per unit area, Poisson ratio and thickness of the panel. This region is controlled by the mass of the panel.

Region 3: defined as the region above the critical frequency. It is controlled by damping.

There are regions, between 1 and 2 where the fundamental and higher modes of resonances occur, where the Q of the resonance peaks are determined by the damping. In a simplistic approach, the region between 2 and 3 is considered a plateau, and also related to damping.

So, plinth design is complex. It is obvious we need mass and damping and a certain thickness. With the results generated today, we can move forward.  :fleur: fête gâteau d'anniversaire
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MessagePosté le: Jeu 4 Fév - 16:43 (2010)    Sujet du message: Damping factors Répondre en citant

I'll run quickly to buy 500kg of cat's litter before the prices rise up Very Happy
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MessagePosté le: Jeu 4 Fév - 17:41 (2010)    Sujet du message: Damping factors Répondre en citant

François a écrit:
I'll run quickly to buy 500kg of cat's litter before the prices rise up Very Happy
ensure it is bentonite, there are many kinds!

The sample you sent, did you or Rap make it? Do you have the ratio of clay to resin? Do you know the origin of the bentonite, and sieve size? They may be important. musique
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MessagePosté le: Jeu 4 Fév - 17:53 (2010)    Sujet du message: Damping factors Répondre en citant

Bryan a écrit:


The sample you sent, did you or Rap make it?

No, I made it!

Citation:
Do you have the ratio of clay to resin?

As much bentonite as possible. There must be no resin that remains on top when casting/mixing.

Citation:
Do you know the origin of the bentonite,

Yes:


Seriously now: E.U., nothing more precise.

Citation:
and sieve size?

Sieve size? You mean the size of the grains Question
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MessagePosté le: Jeu 4 Fév - 18:13 (2010)    Sujet du message: Damping factors Répondre en citant

François a écrit:
Bryan a écrit:


The sample you sent, did you or Rap make it?

No, I made it!

Citation:

Do you have the ratio of clay to resin?

As much bentonite as possible. There must be no resin that remains on top when casting/mixing.

Citation:

Do you know the origin of the bentonite,

Yes:


Seriously now: E.U., nothing more precise.

Citation:

and sieve size?

Sieve size? You mean the size of the grains Question
yes, grain size, usually expressed as a sieve size range, it could be important. What is the name of the maker of the kitty litter, does it say 'bentonite' on the packet?

Sorry if I sound pedantic, but I have been through similar scenarios many times in a professional capacity, and I know things get mixed up (and then take months to sort out!)

Do you envisage making any more in the near future, is it possible to measure things then?
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MessagePosté le: Jeu 4 Fév - 18:18 (2010)    Sujet du message: Damping factors Répondre en citant

Bryan a écrit:
yes, grain size, usually expressed as a sieve size range, it could be important.

As a picture is worth thousand words:






Citation:
What is the name of the maker of the kitty litter, does it say 'bentonite' on the packet?

The maker is "Carrefour" a chain of supermarkets.
And yes, it clearly states that it is made of bentonite.


Citation:
Do you envisage making any more in the near future, is it possible to measure things then?

More plinths you mean Question
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MessagePosté le: Jeu 4 Fév - 18:34 (2010)    Sujet du message: Damping factors Répondre en citant

plinths, anything. I just wanted to know the ratio. I suppose I could work it out, but the irregular shaped grains makes this a little more difficult (irregular grains pack better than spheres for some reason!)

I noticed the sample you sent has small grains one side, large the other. Is this a result of leaving the mix to stand for a while, as in Stoke's Law.
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MessagePosté le: Ven 5 Fév - 07:30 (2010)    Sujet du message: Damping factors Répondre en citant

Bryan a écrit:
plinths, anything. I just wanted to know the ratio. I suppose I could work it out, but the irregular shaped grains makes this a little more difficult (irregular grains pack better than spheres for some reason!)

Well, as I told you, the ratio is quite empirical, but I think there is some kind of rule when adding a charge to a resin (or the opposite), 2/3 charge, 1/3 resin.

Citation:
I noticed the sample you sent has small grains one side, large the other. Is this a result of leaving the mix to stand for a while, as in Stoke's Law.

Yes, smaller grains must have migrated through the bigger, but not when the poly was poured (it is relatively thick and cures quite fast), rather when I poured the bento in the mould, then the smaller grains remained at the bottom of the mould.


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MessagePosté le: Ven 5 Fév - 09:13 (2010)    Sujet du message: Damping factors Répondre en citant

Bryan,

Could you publish the same graphs for these 3 samples than the ones you made in the other thread Question


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MessagePosté le: Ven 5 Fév - 10:26 (2010)    Sujet du message: Damping factors Répondre en citant

hello,

i don't know if it can be any helps, but, your discussion reminds me all the theory about how concrete aggregates.
we call the granulometric spectrum (spectre granulométrique, not sur about that translation) the way différent size and shappe objects can be as packed as possible, and so the less binding agent you need to make an homogeneous block.

there's a program made to determine all kind of things with a lot af variable, that i think can be used in your case to determine what quantiti of each product should be added to give this or that result.

i don't know if that is clear for everyone. but try to take a look at betonLABPro 3, there's a free trial version that can be downloaded here :
http://www.lcpc.fr/fr/produits/betonlabpro/tele_free.php
(sorry, it's in french)

good luck

JD
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MessagePosté le: Ven 5 Fév - 11:25 (2010)    Sujet du message: Damping factors Répondre en citant

François a écrit:
Bryan,

Could you publish the same graphs for these 3 samples than the ones you made in the other thread Question


hats off


 here you go, I've tried to keep them with the same time scale, to give you an idea for comparison:

aluminium laminate:



bentonite polyester:



panzer:



even though I have tried to keep the time axis the same, the software does not allow me to do that accurately. Sad

You will notice the frequency is higher for the aluminium laminate than for the other two. This is a consequence of the thickness of each sample, and of their stiffness, to some extent.
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MessagePosté le: Ven 5 Fév - 11:32 (2010)    Sujet du message: Damping factors Répondre en citant

Bryan,

In order to be able to do quick compairisons, I hope it's not asking you too much , if I ask you to make the graphs with the same scale than those of the "tennis balls" thread Question

Then, we could put them side by side, possibly in a thread.
That would be good for records, no Question

bow


hats off
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