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Linn Forums / Linn Music Systems & Hi-fi Separates / Turntables & Record Players: Linn Sondek LP12 / 3rd Party Modifications and Parts v / Corian Sub Chassis

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Corian Sub Chassis
2017-07-25, 10:13
Post: #11
RE: Corian Sub Chassis
(2017-07-25 09:30)Dr_Eddie Wrote:  Correct, one of the best ways to kill an LP12 is to add damping to anywhere , particularly the subchassis.
The Keel rings like a bell.

This is correct and it's what you want.

If held carefully, our Plateau when struck sounds like the intro to AC/DC's Hells Bells!!!

Regards,

Mark
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2017-07-26, 20:57
Post: #12
RE: Corian Sub Chassis
(2017-07-22 14:04)Mikeg Wrote:  
(2017-07-22 09:11)paulski Wrote:  
(2017-07-20 10:39)Mikeg Wrote:  
(2016-11-07 13:44)ryl1e Wrote:  Another chassis....
Interesting blurb... inert material..

http://www.ebay.co.uk/itm/Linn-LP-12-Son...SwHMJYGe~N

Trouble is the subchassis is not supposed to be inert

Err, I think you'll find the Keel is pretty inert.

Nope! Look at the Linn video comparing the keel to the kore. One of the plus points for the keel was that it rang more than the kore. The subchassis has to allow energy transmission rather than damp it to enable the closed loop design to work

Wrong. Inert and resonant are very different things.
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2017-07-27, 08:56
Post: #13
RE: Corian Sub Chassis
(2017-07-26 20:57)paulski Wrote:  Wrong. Inert and resonant are very different things.

Sorry if I misunderstood you. I read your 'inert' to mean something that does not transmit energy. In what sense were you using the term?
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2017-07-27, 10:34
Post: #14
RE: Corian Sub Chassis
(2017-07-27 08:56)Mikeg Wrote:  
(2017-07-26 20:57)paulski Wrote:  Wrong. Inert and resonant are very different things.

Sorry if I misunderstood you. I read your 'inert' to mean something that does not transmit energy. In what sense were you using the term?

Inert is one of those words that seems to be used in audio circles to imply all sorts of things but it's true meaning can't really be applied to an object other than in the sense of it being motionless or perhaps chemically inert. It doesn't mean stiff or 'acoustically dead' in the sense that an object absorbs energy when struck rather than 'ringing' in the way the Keel and Plateau will if held at the edge and firmly struck.

Then again the audio world is full of many other words used completely incorrectly, just look at the poetic licence exercised by reviewers to describe the way equipment sounds....
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2017-07-27, 15:05
Post: #15
RE: Corian Sub Chassis
The best place for Corian is in a kitchen as work /counter tops or splash backs.
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2017-07-27, 15:19
Post: #16
RE: Corian Sub Chassis
There is nothing wrong with the use of the word "inert" in this context.

The first definition given in several dictionaries is "the inability to move."

Resonant implies large excursions at characteristic frequencies.

Designs to obtain specific resonant frequencies require careful consideration of the mass, stiffness, and damping distributions.

These could be sought experimentally, or, with modern modeling software.

Just listen .... or not
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2017-07-27, 18:30 (This post was last modified: 2017-07-27 18:31 by Peer Gynt.)
Post: #17
RE: Corian Sub Chassis
I was thinking about this a bit more. When you design a part that is supposed to be rigid to ring, it must be with the goal of having minimal damping and a first critical frequency well above the highest expected excitation frequency. This would assure that subcritical excitations would lead to rigid body modes without amplification or other distortion due to resonance.

The expected input excitations would be from the bearing. I speculate that these are relatively low compared to the Keel's first critical frequency.

It may be possible to judge subchasses by the frequency and amplitude of their lowest natural frequency.

I wish I'd put an accelerometer on my Keel and Kore before they were installed and taken a look at how they compare. My old pre-Cirkus subchassis could not be described as bell like.

Just listen .... or not
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2017-08-24, 10:50
Post: #18
RE: Corian Sub Chassis
"Ringing" is just resonant movement at specific frequencies.
No materials used in the context of turntable engineering are truly "inert".
It's all about controlling and placing those resonances where you want them... or where they'll do the least harm.

A choice of materials and the design of the component interfaces are the things that give us that control.

The thing folks can never agree on is exactly how many ways in which it's possible to skin the cat.
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2017-08-24, 13:37
Post: #19
RE: Corian Sub Chassis
I think it's apparent.

Reducing damping narrows the bandwidth of all resonances. Ringing and sustain are signs of reduced damping. Now, if you put the expected input excitations below the first resonance, or between two resonances, then at steady state the output from the inputs will not be amplified. So now you work to to be sure inputs are as low as possible.

It's simple textbook first principles in vibration and noise control (NVH in the auto industry), and it leads to the Cirkus Keel as an elegant solution.

Just listen .... or not
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2017-08-24, 17:39
Post: #20
RE: Corian Sub Chassis
Anyone tried any of the Corian products on their decks?
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