Ideas for granite platforms

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pstrisik

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Ideas for granite platforms
« on: 3 Aug 2014, 06:35 pm »
Hello Steve and other tube damping enthusiasts!   :wink:

Next project for me are bases for my pre and power amp.  These are both Dennis Had's Inspire designs.  My avatar is a photo of the amp.  They are rather small - 8.25" x 10.25" each.  I haven't weighed them.  The pre is pretty light and evenly weighted.  Under 20 lbs I'm sure.  The amp is probably 25-30 lbs or so with weight towards the back and to the rear right corner where the power transformer is.

I'm planning to put them on granite slab bases that will be heavy.  I have a piece that I will have cut and polished for two platforms 8.5" x 10.5" or so and 1" thick.  I will wait until I get them cut to get exact weights of the each platform and each unit.

The pre and amp have the large soft feet - same as Cary equipment.  I'm not sure where I should be focused.  Should I concentrate on something between the bases and the top of the rack or between the equipment and the bases?  Does granite have any problems in picking up vibration on its own?  Those kind of questions.  Anything to get me started would be appreciated.

...........Peter


FullRangeMan

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Re: Ideas for granite platforms
« Reply #1 on: 3 Aug 2014, 07:11 pm »
If possible avoid stones, granite are too dense, it will enhance sub 30-40Hz freq IMO.
Use real wood in one piece of slab or several strips of wood glued side by side.
My 2 cents.

Obs.: I also give up use wood boxes filled w/sand.

WireNut

Re: Ideas for granite platforms
« Reply #2 on: 3 Aug 2014, 08:03 pm »
Go on craigslist and search for "Surface Plates, granite plates, machine tools ect". They are thick granite plates use for inspection in machine shops.


WGH

Re: Ideas for granite platforms
« Reply #3 on: 3 Aug 2014, 08:27 pm »
I found this research paper interesting, below is the first paragraph:

Behavior of granite-epoxy composite beams subjected to mechanical vibrations
http://www.scielo.br/scielo.php?pid=S1516-14392010000400012&script=sci_arttext

"The capacity to damp mechanical vibrations is one of the most important properties of granite-epoxy composites, even superior to the cast iron one. For this reason, these materials have been adopted for manufacturing of tool machine foundations and precision instruments. This work presents a study concerning the behavior of particulate composite beams, based on granite powder and epoxy, subjected to mechanical vibrations. Composite samples were prepared with different combinations of processing variables, like the weight fraction of epoxy in the mixture and size distributions of granite particles. The damping behavior of the material was investigated adopting the logarithmic decrement method. Samples, in the form of prismatic beams, were excited in the middle point and the output signal was measured in a point located at the extremity. The obtained results showed that composite samples, with weight fractions of about 80% of granite and 20% of epoxy, presented damping properties approximately three times greater than gray cast iron."

Photon46

Re: Ideas for granite platforms
« Reply #4 on: 3 Aug 2014, 08:45 pm »
If this thread gains traction, you'll receive so many diverse opinions about the right way to deal with bases, platforms, vibration absorption/damping you'll likely be none the wiser and probably just confused :icon_lol:. The subject of vibration control is one of the most contentious in audio,  gets some people as rilled up as discussions about power cords, interconnects, and power conditioning. I've investigated numerous approaches but never spent serious coin on things like Stillpoints  (although I'll probably end up trying them.) I've never heard any approach make "jaw dropping" or "huge" improvements like some claim to hear. Granite, wood, glass, acrylic, steel, all have their own resonant frequency. Whether a particular material's resonant frequency in concert with any given component will be perceived as good or bad is not a given, experimentation is required. Blanket statements about this or that material's suitability is usually proven wrong in at least one instance. For instance, I'd agree with Fullrangeman about sandboxes in most cases. However, I've got my PS Audio P300 supported by spikes bolted to the bottom plate. Those sit in Boston Audio Tuneblock S's that in turn are sitting on a sandbox. Getting rid of the rubber feet that the P300 came with and installing this system did result in audible improvements better than any granite or maple platform or any other footer i've tried. I would say the Boston Audio Tuneblocks are best reasonably priced vibration control device I've tried as far as making audible improvements in a number of components. Whether a platform alone makes a difference depends on the component. I've had three turntables that all sounded much better on a thick maple plinth like Fullrangeman suggested. On the other hand, my Luxman cd player doesn't care what it sits on. The mdf shelf in the rack, a maple platform, and a granite platform all sound the same.

werd

Re: Ideas for granite platforms
« Reply #5 on: 3 Aug 2014, 09:11 pm »
If possible avoid stones, granite are too dense, it will enhance sub 30-40Hz freq IMO.
Use real wood in one piece of slab or several strips of wood glued side by side.
My 2 cents.

Obs.: I also give up use wood boxes filled w/sand.

I agree, I've always found something wrong with granite. It doesn't absorb frequency but seems to reflect it. Encased granite might be good as core for a platform.

Herbie

Re: Ideas for granite platforms
« Reply #6 on: 3 Aug 2014, 09:16 pm »
Hi, pstrisik. Regardless of platform material, the isolation/decoupling interface between the platform and component is virtually always most essential. For the components mentioned, Herbie's regular Tenderfoot isolation feet between each component and platform in place of the stock feet should be ideal.

The interface between platform and shelf is also important; regular grungebuster Dots are an excellent decoupling interface between platform and shelf.

Best regards,

Steve
Herbie's Audio Lab

pstrisik

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Re: Ideas for granite platforms
« Reply #7 on: 4 Aug 2014, 12:58 am »
Hi, pstrisik. Regardless of platform material, the isolation/decoupling interface between the platform and component is virtually always most essential. For the components mentioned, Herbie's regular Tenderfoot isolation feet between each component and platform in place of the stock feet should be ideal.

The interface between platform and shelf is also important; regular grungebuster Dots are an excellent decoupling interface between platform and shelf.

Best regards,

Steve
Herbie's Audio Lab

Thanks Steve,

Tenderfeet is what I had in mind for the components.  I wasn't sure about the granite situation.  It is more decorative than for sound, but I want to make sure it isn't adding a negative in that regard.  Some of the opinions here indicate that it might be.  Do you have an opinion about that?

@WGH - the only problem is that I already have the granite slab, so it won't be the epoxy/granite compound.

@others - I'll take a look at the suggestions, thanks!

.........Peter


Herbie

Re: Ideas for granite platforms
« Reply #8 on: 4 Aug 2014, 02:01 am »
Just about any material for a platform will introduce some character or color, including granite. By appropriately isolating/decoupling the granite, it does very well and has potential to be sonically beneficial, depending on how the granite interacts with your system synergies and personal taste. Any "character" will be greatly minimized by isolating rather than coupling the granite into your system. Strictly on its own, without isolation, granite can have a bit of a glare to it.

We have lots of customers using granite for setting speakers on and as component platforms like you've described. No better or worse than maple butcher block or expensive engineered platforms, if well isolated. Grungebuster Dots underneath have been tried and proven over and over again through the years to be an excellent and inexpensive decoupling material under just about any kind of component platform, including granite. I use granite slabs on top of floorstanding loudspeaker cabinets with very good sonic benefit (decoupled from the speaker cabinets with "Thin" Fat Dots in-between).

Steve
Herbie's Audio Lab


jamesg11

Re: Ideas for granite platforms
« Reply #9 on: 13 Aug 2014, 07:05 am »
Hi, I'm one of those who has spike-coupled speakers to granite slabs, &, yep, getting some glare, etc ...
My Elac FS249BE floorstanders are 30+kgs. Which Herbie product is likely to work best here? Easiest to simply put the spikes onto an isolation product, though non-spiked is an option.

Herbie

Re: Ideas for granite platforms
« Reply #10 on: 13 Aug 2014, 01:40 pm »
Using four Big Fat Dots (or Square Fat Dots) between each speaker and slab would be ideal, in place of the spikes. Or, a Fat Grounding Base under each of the spikes would accomplish the same excellent isolation/decoupling. The only difference would be slightly different speaker height, which might have some acoustic effect on the speakers' acoustic interaction with the listening room.

Steve
Herbie's Audio Lab

Wayner

Re: Ideas for granite platforms
« Reply #11 on: 13 Aug 2014, 02:02 pm »
Hi, I'm one of those who has spike-coupled speakers to granite slabs, &, yep, getting some glare, etc ...
My Elac FS249BE floorstanders are 30+kgs. Which Herbie product is likely to work best here? Easiest to simply put the spikes onto an isolation product, though non-spiked is an option.

Why are you doing this? would you not be better off spiking your speakers to the floor? The object is to remove cabinet resonance, so you need to have a coupling to a drain field (your floor). Isolating the speaker will make it sound even more muddied, IMO.

Herbie

Re: Ideas for granite platforms
« Reply #12 on: 13 Aug 2014, 02:55 pm »
"Draining" to the floor does not efficiently absorb cabinet vibrations, and speaker-generated vibrations draining to the floor will resonate and travel right back up the spikes the way they came, usually causing some glare and harshness.

With appropriate isolation/decoupling, you'll usually get a better-defined and more dynamic musical result, more faithful to the originally recorded event by bringing out more of the speakers' inherent potential. Most common comment and feedback from customers is better-defined bass response. With dBNeutralizer isolation, you'll get a more linear result with subtle improvements throughout the audio spectrum compared to using conventional spikes.

(Isolating with poor materials like Sorbothane, rubber, vinyl nitrates, or other resonance-prone materials will usually give a muddied sound or other loss of linearity.)

Steve
Herbie's Audio Lab

 

jamesg11

Re: Ideas for granite platforms
« Reply #13 on: 13 Aug 2014, 11:59 pm »
Why are you doing this? would you not be better off spiking your speakers to the floor? The object is to remove cabinet resonance, so you need to have a coupling to a drain field (your floor). Isolating the speaker will make it sound even more muddied, IMO.
Originally, I had the Elacs into the floor, & then tried the granite slabs - the immediate 'benefit' was a tighter, chunkier bottom end ... but, over time, the other resulting defects became obvious.

So, I guess I'll try the Fat Dots between the slabs & speaker & see how that goes. Height is about right, with the Jet tweeters at head level in my sitting spot. Also, need to look at other components ...

jamesg11

Re: Ideas for granite platforms
« Reply #14 on: 14 Aug 2014, 01:52 pm »
Would the Ascendo C8 Special ie 10x extra thick Fat Dots (one for the middle of each speaker base) be optimum? & similarly for my large power amp which has a central support in addition to the 4 corners, would 5x Iso-Cup w/SuperSonic Hardball be optimum?

Herbie

Re: Ideas for granite platforms
« Reply #15 on: 14 Aug 2014, 02:23 pm »
Fat Dots are highly efficient. Extra-Thick Dots with Ascendo Special wouldn't be overkill, but more than you need. A fifth Dot under the middle of a speaker cabinet always has potential for additional benefit; I would suggest the Von Schweikert Special for the moderate-weight C8 speakers.

Either five Iso-Cups w/SuperSonic Hardballs or five Extra-Firm Tenderfoot isolation feet should do very well with the amp. Four is usually sufficient, but with an amp that has a fifth support, there's usually a benefit there. With amps having a fairly large base or "footprint," a fifth footer is usually beneficial, anyway. With free-standing Iso-Cups or Tenderfeet, you have lots of latitude regarding placement of the footers, so can usually find optimal locations for the footers--usually, just placing them where they seem right achieves more than satisfactory results, though some experimenting/auditioning with placement can sometimes be rewarding. Neither Iso-Cups nor Extra-Firm Tenderfeet have inherent advantage over the other--either should do very well; subtle comparative differences between them sonically will vary from one system to another, depending on vibrational environment and overall system variables and synergies.

Steve
Herbie's Audio Lab


jamesg11

Re: Ideas for granite platforms
« Reply #16 on: 14 Aug 2014, 09:30 pm »
Thanks Steve,
just checking that the Ascendo C8 Special Fat Dots are just larger versions (not a different unsuitable shape) & would work fine under the ~35kg Elacs? A relevant(?) design issue with the Elacs is that the base is below a down-firing bass port (& there's also one at rear further up).



Herbie

Re: Ideas for granite platforms
« Reply #17 on: 14 Aug 2014, 09:54 pm »
Hi, James. Big Fat Dots, Square Fat Dots, Von Schweikert Special, Ascendo C8 Special, etc., are all exactly the same, identical dBNeutralizer material, just different physical dimensions.

Steve
Herbie's Audio Lab