Slate/marble/granite pads or one big slab?

steve4232

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Further to another topic regarding MA speakers and general discussion about bass in the room and isolating "boom", I have a related question about hi-fi racks on suspended uneven and bouncy timber deck flooring. My "Soundstyle XS 105" currently holds all my AV kit together. The problem is that although it is solid in itself, it moves freely around and "sways" at the top due to the floor it is sited on.

Would it be better to plant a heavy slab of slate or marble or granite on the floor first and then sit the rack on top of this? I can then adjust the spiked feet to level it. There is a possibility that the slab won't be level due to the floor though. Alternatively I could simply put small plates or pads of steel (?) or another solid non flexible material under each leg to spread the load from the spiked foot and to give it something solid to rest on. Which is the best idea? Presumably putting an absorbent material under the solid material won't help me as, even with the substantial weight upon the spiked feet, the tower will still not be rock solid due to the flexibility of the substrate?
 

Vladimir

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Bitumen sheets under the granite slabs and problem solved. For fine leveling use the feet of the rack.

28Sep2011_2777.png


Alternatively you can use coins under the granite and try to position them so there is no rocking of the slab on the wooden floors.
 

steve4232

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Thanks! Would you suggest granite or is marble or slate the better material? What thickness do you think I need to prevent it splitting or fracturing? I hate to think what pressure those 4 spikes will put on a single point load? The total weight of kit including the rack will be over 100kg!
 

Vladimir

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Which is 25-30kg per each point. Not that of a big deal for 1.5" thick granite.

Granite is very dense material formed deep in Earth's core unlike marble which is a sediment from former sea beds. Granite should be better isolation from vibration and it is reasonably scratch resistant.

Do you plan on using two rectangular bits under the left and the right side of the rack?
 

steve4232

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Vladimir said:
Which is 25-30kg per each point. Not that of a big deal for 1.5" thick granite.

Granite is very dense material formed deep in Earth's core unlike marble which is a sediment from former sea beds. Granite should be better isolation from vibration and it is reasonably scratch resistant.

Do you plan on using two rectangular bits under the left and the right side of the rack?

No, if I'm going to use granite it is far more likely I'll use one square slab. Kitchen worktops are 600mm deep so if I could get an off-cut 600mm long of black granite w/top I'd have a perfect square to comfortably place my rack on. I think w/tops are 38mm -40mm in thickness so that would also work out ok.

It's a pity that's a US site the link above is to. I can't find a UK website offering small steps like that! :wall:
 

Vladimir

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You can also use square bits of bitumen instead of coins. Nothing kills vibration like it. Even better, a tick sheet under the TT.
 

steve4232

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Overdose said:
I would use coin stacks as required. Two pence pieces would be ideal. Once you know how many you need, you could glue them together with a metal adhesive.

Do you mean use nothing but coins ie. no granite? It'd certainly work out much cheaper if nothing else!!!! :rofl:
 

Vladimir

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I'm suggesting what to use under the granite slab since it will sway/rock if the wooden floor is uneven. So you have two choices, use feet (coin or custom made feet) or soft material that will compensate for 1-2.5mm of bumps (rubber, neopren, bitumen, silicone). Soft material not too thick.

The soft padding solution will keep your floors free from scratches and dents. Coins and feet will dig in and leave marks. 100kg+ the granite, it's no joke.

God knows I've tried everything possible and just said to hell with it all, just stick the spikes on the floor and forget about it. I just filled the rack tubes with sand and used bitumen or granite or marble individually on components that benefit (TT, CDP). This was in my previous systems with bigger speakers. Now with the little CM1's I don't bother with isolation, just keep everything on spikes and only the voltage stabilizer is on block of marble so it won't heat up on the floor. Keeps it cool.
 

Overdose

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steve4232 said:
Overdose said:
I would use coin stacks as required. Two pence pieces would be ideal. Once you know how many you need, you could glue them together with a metal adhesive.

Do you mean use nothing but coins ie. no granite? It'd certainly work out much cheaper if nothing else!!!! :rofl:

As I understand it, you just want to level your hifi rack, why would you want or need to use granite slabs?
 

steve4232

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Overdose said:
steve4232 said:
Overdose said:
I would use coin stacks as required. Two pence pieces would be ideal. Once you know how many you need, you could glue them together with a metal adhesive.

Do you mean use nothing but coins ie. no granite? It'd certainly work out much cheaper if nothing else!!!! :rofl:

As I understand it, you just want to level your hifi rack, why would you want or need to use granite slabs?

Because the floor is not level and quite uneven. Even though the XS105 can be "levelled" by screwing the spiked feet up or down to vary the height, I've found it is an abysmal design / flaw. As you unscrew the spiked foot from the fully turned in/locked position, it becomes wobbly and unstable. So much for feet adjustment! This thing only stays rigid when all 4 feet are equally screwed in tight.

The theory is that a slab of granite would be level, unlike my floor so if I had a slab I coudl at least stick the rack on it and get it rigid. All I then have to do is find the best way of getting the slab level and prevent it from rocking. I think I'll try the coin stack idea BETWEEN the bitumen sheet (to absorb vibration and prevent further floor damage) and the slab as I will have gaps up to 12mm to fill in some places.
 

Overdose

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I still fail to see why you would need a slab of stone, which in turn would need to be levelled.

If your stand adjuster feet do not have lock nuts, get some fitted and then tighten them when the feet are adjusted correctly. You will then have no wobble.
 

steve4232

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Overdose said:
I still fail to see why you would need a slab of stone, which in turn would need to be levelled.

If your stand adjuster feet do not have lock nuts, get some fitted and then tighten them when the feet are adjusted correctly. You will then have no wobble.

That would be very easy and I agree that with most speaker stands or Target type it is feasible. However the rack has screw-in cone shaped feet that simply go into the threaded tubular corner posts. There is nowhere to install a "lock nut" sadly. They're either screwed in as far as they will go and give the requisite rigidity to the rack or they have some play in them if the coned (spiked) feet need to be unscrewed slightly to lower one foot where the substrate isn't perfectly level. In my case there is about 12mm / 1/2" difference in level from front to back.
 

Overdose

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Hmm, ok.

How about fitting shims to the feet?

Large rubber tap washers might do the trick, this will pack out the space between the cones and the stand and allow you to tighten them.
 

steve4232

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I'll certainly take a look at shims but I think the diameter of the cones is probably too large to accommodate most widely available sizes. The thing is there isn't enough of a flange for the shims to rest against to be effective enough. It's just the thickness of the gauge of the steel tubing. Thanks for the suggestion.
 

Vladimir

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You can't shim 12mm. That is a bloody pothole. :?

The advantages of the granite slab are:

- stiff, perfectly leveled surface

- scratch resistant

- vibration dampening

Instead of bodging the (I presume expensive) rack, let the slab and some bitumen+coins take the pothole on the bottom and the rack will sit perfectly leveled on a nice surface on top.

Might be a good idea to use a spirit level to make sure everything is perfectly horizontal. Those are cheap in any hardware store. I wouldn't trust phone app level meter.
 

steve4232

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Excellent advice, Vlad, thanks!

I do have two spirit levels but I'm not sure which one to trust! The longest or the shortest? They both say different things. I guess the 60cm long metal "builders type" would be the one to use? My smaller (and more convenient) plastic unit at 15cm long shows it level when the longer one says it's out of level. They can't both be right.
 

Vladimir

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The longer one would be more accurate since it measures a wider surface.

You can experiment now with some flat wooden board you dont use, coins and the level tool. If the results are satisfactory you can buy a granite slab later. Might be really tough to try and learn as you go with that heavy slab.
 

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