Slate Rack Design

[Whaleblue]

For those that have an interest and knowledge in this area, I'm sourcing a new rack from these chaps...

http://slateage.com/hifi/hifi-racking-system/ (Scroll to the bottom to see the current design).

...but am currently undergoing discussion with them as to how best to construct it - i.e. how should the layers be coupled etc.

I'm going for 5 tiers, and was concerned with getting 5 sets of adjustable spikes (the current method they employ) set such that the rack is stable and level. I've therefore been going over possibilities with them. My primary concern is that it looks good, and provides a level top shelf suitable for my granite plinth'ed 301.

An idea we've come up with is to largely ignore isolation between the layers, and have the whole structure held together with a long chrome bolt going down through each set of legs (and obviously through the shelves), terminating at the very bottom by large spiked feet into which the bolts will screw.

Included between each shelf and the leg above it would be a Sorbothane disc of about 3mm thickness (also "speared" by the bolts) which would allow for a very small amount of levelling correction of the top shelf only. The legs are likely to be cut to a tolerance of less than 0.2mm, so I can't see the other layers being very far out.

One thing to note is that the chrome bolt will not be an interference fit with the slate (apparently not possible to drill everything to the precision that that would require), so the construction will require a certain amount of fiddling to get everything squared and in line. I don't expect to build it more than once, so I think I'm comfortable with that in order to get a super solid structure.

Clear?

Anyone interested enough to comment?!

 

[Biggus-Dickkus]

What about North West Analogue?

They make some nice slate racks.

 

[Whaleblue]

What about North West Analogue?

They make some nice slate racks.

Compare pics with Slate Age's pics (who actually make these). I think you'll find NWA are a reseller. I don't know for sure, but I do know when I speak with SA they're the guys who run the cutting machines. FWIW NWA are doing my Troika re-tip though - nice people!

 

[stevec67]

Included between each shelf and the leg above it would be a Sorbothane disc of about 3mm thickness (also "speared" by the bolts) which would allow for a very small amount of levelling correction of the top shelf only. The legs are likely to be cut to a tolerance of less than 0.2mm, so I can't see the other layers being very far out.

That's sound reasoning and a very conventional method, so it will work.

One thing to note is that the chrome bolt will not be an interference fit with the slate (apparently not possible to drill everything to the precision that that would require), so the construction will require a certain amount of fiddling to get everything squared and in line.

Nonsense, if they know what they are doing and have a lathe, which they should do. Anyone with an ounce of wit and engineering skill can drill these things to within a fraction of a millimetre so the "fiddling" should be minimal if the designer and builder do their jobs properly.

 

[Whaleblue]

Thanks Steve.

Yes, I was mildly surprised about the hole drilling. Of course I didn't mean interference fit I simply meant close fit as you'll have realised. I'll ask him in more detail.

Any thoughts on the lack of decoupling between layers that this design lacks? My logic is that as it will weigh around 100Kg it'll not move much at all anyway!

 

[reefhead]

Well, I have a three tier rack from Slateage as per the current design. Happily sat atop is my NWA/Slateage plinthed 401 and all is very stable and easy to level. Looks and sounds lovely! I'm sure, considering the mass, another two layers would be fine.
Must say, Slateage were excellent to deal with and the overall look and finish never fails to impress our visitors!

 

[formbypc]

Three spikes are far easier to level, and make stable, than four.

 

[reefhead]

4 legs / spikes on my rack layers, but 3 legs on my plinth. Think the spike coupling on each layer actually makes adjustment / levelling easier working from bottom up.

 

[Whaleblue]

Well, I have a three tier rack from Slateage as per the current design. Happily sat atop is my NWA/Slateage plinthed 401 and all is very stable and easy to level. Looks and sounds lovely! I'm sure, considering the mass, another two layers would be fine.
Must say, Slateage were excellent to deal with and the overall look and finish never fails to impress our visitors!

My concern is that whilst three layers may be easy, it gets exponentially harder as you add more layers.

Three spikes are far easier to level, and make stable, than four.

I hate levelling with spikes, but yes three better than four!

 

[AndyU]

Can you not give it some more useful acoustic properties?

 

[Whaleblue]

Can you not give it some more useful acoustic properties?

Ears?

What are you thinking?

 

[PaulMB]

The slate rack is in layers of which you can purchase in stages. Each layer is constructed with four legs of which bolt to the rack platform by means of m12 stainless steel nut and bolt. Of which uses Slate Ages solid CNC fixing. The base of each leg has a steel adjustable spike which when placed over another platform drops into the counter sunk hole below.

I hope they take more care in making their racks than in the grammar of their description!

 

[paskinn]

Can you not give it some more useful acoustic properties?

Quite. Does slate isolate well? I'd suspect that a well-made solid wooden rack would provide a better solution. Slate rings. And sheer mass won't do the job. Have a look at what 'Hush' offer to see what sort of thing can be achieved.

 

[Blade1001]

The slate racks do look good. What sort of price are we looking at for these Vital?

 

[YNWOAN]

I've actually built structures like that described in the OP and all of the Alphason racks used this bolt through construction.

It depends on what the OP means by 'super solid', if he means 'rigid' then it will not be and by some margin. The compliant disks between layers will give quite a wobbly quality to the whole thing. Also, some seem to believe slate to be a naturally damped material. Whilst this is a nice idea, my experience is that, whilst stiff, it is actually quite lively and undamped - this may be a good or a bad thing depending on your perspective.

I'm considering building new racking for my gear - but slate isn't on my list of material choice.

 

[Whaleblue]

I hope they take more care in making their racks than in the grammar of their description!

Yes, as long as they know their trade I'll ignore their English!

Quite. Does slate isolate well? I'd suspect that a well-made solid wooden rack would provide a better solution. Slate rings. And sheer mass won't do the job. Have a look at what 'Hush' offer to see what sort of thing can be achieved.

Interesting. I note that slate is now one of the top choices for 301/401 plinths(Tony amongst many others has one), so assumed it was a generally good choice for HiFi).

The slate racks do look good. What sort of price are we looking at for these Vital?

Around £800 for the 5 tier version.

I've actually built structures like that described in the OP and all of the Alphason racks used this bolt through construction.

It depends on what the OP means by 'super solid', if he means 'rigid' then it will not be and by some margin. The compliant disks between layers will give quite a wobbly quality to the whole thing. Also, some seem to believe slate to be a naturally damped material. Whilst this is a nice idea, my experience is that, whilst stiff, it is actually quite lively and undamped - this may be a good or a bad thing depending on your perspective.

Hmm, perhaps their original design with four spiked feet per layer, whilst fiddly to get right, might be the best option after all?

 

[YNWOAN]

If a stiff structure is wanted then yes, it probably is better. However, consider that some manufacturers intentionally allow a low frequency sway to exist in their rack systems.

 

[Whaleblue]

If a stiff structure is wanted then yes, it probably is better. However, consider that some manufacturers intentionally allow a low frequency sway to exist in their rack systems.

Well, my objective is to give the "best" support to my granite plinthed 301 which will, of course, sit on top.

Part of the reason for going slate rack / granite plinth is that my understanding is that mixing materials can help - presumably because frequencies that resonate in one will not in the other?

 

[YNWOAN]

Part of the reason for going slate rack / granite plinth is that my understanding is that mixing materials can help - presumably because frequencies that resonate in one will not in the other?

It can, but there is absolutely no guarantee that it will and how that material is used and coupled to other materials makes at least as much difference as what material is actually used. By mixing materials you are, in effect, making a mechanical filter and trying to make a better filter by combining two different ones. The problem is that you can easily end up attenuating some frequencies at the expense of others and end up with quite a chaotic result.

In relative terms, your granite turntable plinth and proposed slate are not sufficiently different in qualities to create much of a filter - birch ply shelves would make more difference (an off-cut of kitchen worktop - laminated chipboard - even more so).

I have read (quite often) that, because of the way slate is created, vibration is dissipated within its structure - now whilst that is a nice idea, I've never encountered any evidence (outside of armchair musings) that this actually happens at the frequencies and amplitudes relevant to hi-fi applications.

 

[Purité Audio]

V if you really want to isolate your turntable from ground borne vibration, then you would be better off looking at a pressurised air isolation platform/table.
Keith.