DIY CLD Plinth Design--A measured Approach

Hi cats squirrel.
I'm happy to be corrected.
My description below will help for me to be offered guidance onto the correct terminologies for the reporting of my trials with materials.

I have spent many hours of my time using various materials,
assembling various types of equipment supports and producing differing methods of separation at the interfaces between Supports and Equipment.

During these trials/experiments there have been occasions where there have been noticeable audible changes as a result of a configuration used.

I have developed a habit of referring to these audible changes as a change to the attenuation / management of ambient energies.

Would it be more accurate if the changes were a referred to as change in a damping factor ?
 
damping factors are usually used to refer to the damping factor of separate materials, rather than structures. I believe the way to go is to construct things like plinths from thin panels (called plates in physics) of highly damping materials. Of course, one should end up with a plinth that adds nothing to the final sound (and by the same reasoning, take nothing away). That is why I always suggest using materials which have high damping ability.


However, this is likely to interest those who don't want 'enhanced sounds', but require some kind of harmonic enhancement to enjoy their music.
 

PRR

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...interested in the Tufnol Brand Materials -
Carp Brand (Cotton Compression)...

Phenolic-cotton was hot stuff for car engine timing gears in 1927:
Development of the Silent Timing-Gear

Phenolic won't ring like cast iron. It was reasonably tough but did not last forever. For several reasons, factories tried Nylon and restorers turned back to steel because good phenolic is now rare (or costly?).
 
I at present use a MU25 Plywood that was a Plinth Material being used regularly before
B15 Panzerholz become a much improved alternative.

I myself am on board with the Thin Materials that have high damping capabilities.

I have 1000 x 800 x 75 (mm) Permali Board on Standby for when I decide to use a improved material for Plinth Construction.
I will Have a Two 75mm Thickness Plinths Produced, and will have one cut into Three Thicknesses of approx 15mm, 20mm, and 35mm.
These will be assessed as Four Different Thicknesses as Plinths.
I am hoping to be discussing my requirement with a Machining Service this year

I am also actively seeking a route to acquire a quantity of Panzerholz as well.

My eyes are always Peeled to look at materials in use by Industries, that might offer a solution for high damping, but these materials need to be proven for purpose beyond ones ponderings of suitability.

As for the comments on the Structure, It is a assembly of Natural Products,
i.e, Granite Stone and Wood and Manufactured Products, i,e, Steel Plates, Birch Plywood, Rubber, Rubber/Foam Composite, Soft Aerated Foam, Compressed Foam Board,
and Two Types of Footers one Type is a Pneumatic Design and the other a Suspension Design.

The results for the assembly will be very subjective if being assessed for its audible effects.

The Conundrum is that a Plinth can't levitate and be totally inert in a space, it has to be mounted/coupled to produce a interface to another material/materials.

I have used a Plinth Mounted on a Wall Shelf, as well as Mounted on a Suspended Platform under a Wall Shelf.
I feel the Method Created for supporting a TT, in using a Stand/Rack that has undergone different configurations of Materials for a Podium Support and the same for the Top Shelf > Sub Plinth Material, has created a structure that offers the best interface for me in the environment it is used.

Even though these Material Assemblies are not CLD in a fundamental accuracy, it is assembly of Teirs of Materials that are not mechanically fastened to each other.
 
I'm working on a plinth for mounting a three phase PMSM motor, and I intend to use 13mm to 18mm Richlite/Panzerholz (if I can get it...) plus two face layers of 3mm Al, glued on with contact adhesive.
Any comments/recommendations on this choice?
Panzerholz is available in sheets from the Canadian distributor, but Richlite is much more convenient/available.
 
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I have been following this thread with great interest.

Ad s follow on to the last post above, does anyone know of a source of panzerholz here in the USA?

I have googled the hell out of it but have not come up with anything

Many thanks for a great and informative thread.

Curt
 
I at present use a MU25 Plywood that was a Plinth Material being used regularly before
B15 Panzerholz become a much improved alternative.

I myself am on board with the Thin Materials that have high damping capabilities.

I have 1000 x 800 x 75 (mm) Permali Board on Standby for when I decide to use a improved material for Plinth Construction.
I will Have a Two 75mm Thickness Plinths Produced, and will have one cut into Three Thicknesses of approx 15mm, 20mm, and 35mm...

I don't understand why you are experimenting with thicknesses of Panzerholz. If you look at the graph of Panzerholz parameters at various thicknesses, you will observe that although the fundamental frequency (and therefore all the harmonics as well) increases as thickness increases (linearly) the critical frequency reduces exponentially. Also note that the goodness factor (a measure of losses from 30 Hz up to 1 kHz) does not change much at or above 15mm. This is quite common with materials with good damping ability. Note that thicker panels (plates) does not mean more damping. It increases mass and bending rigidity, not good!

panzerholz parameters by cats squirrel, on Flickr

...My eyes are always Peeled to look at materials in use by Industries, that might offer a solution for high damping, but these materials need to be proven for purpose beyond ones ponderings of suitability.
There is a point above which extra damping is not thought beneficial. This is said to be about 0.4 any more, and the benefits are slight (little reward on extra costs).


As for the comments on the Structure, It is a assembly of Natural Products,
i.e, Granite Stone and Wood and Manufactured Products, i,e, Steel Plates, Birch Plywood, Rubber, Rubber/Foam Composite, Soft Aerated Foam, Compressed Foam Board,
and Two Types of Footers one Type is a Pneumatic Design and the other a Suspension Design.
You may have gathered that most natural products (and most man-made ones as well) cannot provide the damping factors required.


...The Conundrum is that a Plinth can't levitate and be totally inert in a space, it has to be mounted/coupled to produce a interface to another material/materials...
but one can choose good damping materials and use decoupling to the same end.



...Even though these Material Assemblies are not CLD in a fundamental accuracy, it is assembly of Teirs of Materials that are not mechanically fastened to each other.
I would forget about cld for plinths. It was always intended as a way to damp thin plates, it is essential that the structure bends (to dissipate energy) so thick panels (plates) are counter productive.
 
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" If you look at the graph of Panzerholz parameters at various thicknesses, you will observe that although the fundamental frequency (and therefore all the harmonics as well) increases as thickness increases (linearly) the critical frequency reduces exponentially. Also note that the goodness factor (a measure of losses from 30 Hz up to 1 kHz) does not change much at or above 15mm."

Cat's squirrel, if the platter weighs around 30kgs, do you think a 15mm thick panzerholz plinth is fine or a 25mm thick plinth is preferable?
 
Following the Guidance of the Graph for Panzerholz
It is looking like I will be able to get 4 to 6 Plinth Blanks Produced from one Permali Board cut to the Dimension 10/15mm x 500mm x 400mm.
This should be quite close in their readings to the Graph Information for the P'holz .
 
More tampering

There is a point above which extra damping is not thought beneficial. This is said to be about 0.4 any more, and the benefits are slight (little reward on extra costs).

By memory, I'm thinking I've seen damping numbers around 0.6 for Panzerholz. So, when I bought a 20mm sheet and cut out my 19" x15" panel it surprised me how lively it is when tapped. Maybe it's exactly what I should expect.

But, just to be a zealot, I added some blobs of ductseal and 8mm Panzerholz to the back and screwed it together. Surprisingly dead sounding now. But now it's total thickness is over the desired 20mm (for Fc purposes), so I'm thinking about a thinner version.

I'm attaching a screen grab of the raw pulses. You can see the additional materials do shorten up the decay time.

On the right, I've added the equalized versions. These are processed as you described, but 30db lower overall to avoid clipping.

Would you say I've overdone the damping?

Hugh
 

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  • 19x15 x 20mm pulses when Equalized.jpg
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There is a Project in the UK where a P'holz Plinth has been produced for a TTS 8000.
The Plinth has a Side Wall and is Veneered, the underside of the Plinth was filled with a material referred to as Newplast which is a product produced for the Modelling / Sculptues Market.

Very recently after a extensive use of the Combined Materails Plinth, the TTS 8000 had a Naked Plinth of P'holz produced, with the same Tonearm > Cartridge and > Mounting Rack.
The Naked P'holz was reported by the user as being the most desirable sonically.
I will need to revisit the report to see if the Naked P'holz Plinth had used the same Tonearm base material.
Aesthetically the Veneered P'holz Plinth is as pleasing as a owner could wish for.

I am not sure if there is a comparison being carried out of the P'holz with Veneer Only
vs the Naked Model.