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I built this for a Rega Planar 3 that had a rumble problem. Here is one of my design drawings.

 

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Once again I start with a basic box made from some scrap MDF.

 

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Then some then weathered stone finish and six coats of semi-gloss Deft lacquer finish.

 

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Then I filled it with 25 pounds of glass beads used in bead blasting. It is finer than sand. I topped this with a sheet of glass.

 

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Add the Rega and it was dead quiet. All this sits on four Daruma Isolation bearings. So you get both damping and isolation.

 

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Very cool! I could use something like that. My player is in a bad spot and I don't have the room to relocate it.
 

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Beautiful looking turntable base, but I can´t imagine any special engineering foundation for the design!
What am I missing, that differentiates it from a slab of marble or any other heavy weight mass decoupler?
 

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Nice work. Good fit & finish. I would expect it to isolate well due to the materials of differing densities, plus the sand (blast beads) provide a certain amount of "give" which should absorb & dissapate vibrations somewhat. I am guessing that the problem being addressed isn't actually rumble (from turntable motor & mechanisms), but rather low freq acoustic feedback coupling, from the speakers (when volume is cranked up) thru the floor & furniture and getting back to the TT platter and into the cartridge.
 

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OK I'm an old man, but a newbie here, but what the are Daruma insets? Obviously some sort of foot or isolation device, but ??
It is a great looking base. As I see it, it is a large mass with shock absorbing feet. Where was the "rumble" coming from? If it was from the turntable itself, as I see it, this would work if the rumble was resonating with whatever base the turntable was previously setting on. If it was from an outside source this would possibly be a good isolation device. But regardless, as they say, "if it works", it works, as well as looking good, just don't let those glass beads get into the mechanics of the turntable!

The Grumpy One
 

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Discussion Starter #13
OK I'm an old man, but a newbie here, but what the are Daruma insets? Obviously some sort of foot or isolation device, but ??
It is a great looking base. As I see it, it is a large mass with shock absorbing feet. Where was the "rumble" coming from? If it was from the turntable itself, as I see it, this would work if the rumble was resonating with whatever base the turntable was previously setting on. If it was from an outside source this would possibly be a good isolation device. But regardless, as they say, "if it works", it works, as well as looking good, just don't let those glass beads get into the mechanics of the turntable!

The Grumpy One
Daruma isolation bearings were made by Final Labs. While this is an isolation box, it worked more for damping the table than anything else. The motor generated vibration the high output cartridge picked up easily even at low volume. So, apply a little physics. Glass is a great conductor. It allowed the table vibration (mechanical energy) to excite the glass beads that dissipated it as heat (electrical energy). Like rubbing sticks together, but on a finer scale like a million micro sticks.

I never had issues with outside interference. The marble top was 210 pounds and the floor was hardwood over a concrete foundation.
 

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Thanks for the explanation Wardsweb. So it actually was rumble, from the TT motor ... and your box acts like a kind of "vibration sink". Interesting treatment for TT rumble; good to know, in case anyone has a rumble problem. And, you should get some acoustic decoupling & isolation as a bonus, to help with acoustic feedback and noise from footsteps (which probably aren't an issue with your solid wood over concrete floor).
 

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In another forum (not HTS) awhile back, someone was talking about creating isolation by using a steel ball bearing 1" diameter or so in a slightly concave dish, say 2" across, one of these at each corner of a piece of equipment - speakers to begin with, then other pieces of equipment where vibration could be an issue - turntable or CD player. Said it gave a big improvement in imaging. I know this is a bit different from what you are suggesting, but any experience with isolation of that sort? There was even some discussion about mag-lev bearings and air bearings throughout a system for the same purpose. Any feedback/experience with this?
 

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In another forum (not HTS) awhile back, someone was talking about creating isolation by using a steel ball bearing 1" diameter or so in a slightly concave dish, say 2" across, one of these at each corner of a piece of equipment - speakers to begin with, then other pieces of equipment where vibration could be an issue - turntable or CD player. Said it gave a big improvement in imaging. I know this is a bit different from what you are suggesting, but any experience with isolation of that sort? There was even some discussion about mag-lev bearings and air bearings throughout a system for the same purpose. Any feedback/experience with this?
The ball bearing isolation is what the Daruma Isolation bearings are. One cup is concave and the other flat inside. Your contact area is small giving you the isolation.

You may read about them on Galen Carol's website: http://www.gcaudio.com/products/reviews/infodaruma.html
 

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Looks good and works very well so I hear.
We sand- [and glass] -blast a lot on my work so I have acces to enough deadening-material. My favorite is the material used in our mechanical sandblast-machine; very small balls of steel.
This has a surprisingly high mass and the balls will fill any gap when the enclosure is tapped with a rubber hammer.

Had a good laugh when I filled the hollow legs of the audio-rack with these and asked one of my friends to put it in place "while I hold the cables" ... :innocent: the small rack turned out to be a real back-breaker.

Personally I would not have used glass on the upper layer [ transmits sound [energy] very well], but instead would have used a compound-like sandwich of different materials to add to the dampening even more.

Good build nontheless, congrats!!
 
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