Supports: basic principles please

Read with interest recent exchanges on supports - granite slabs, oak blocks, spikes, sand-filled frames....

Sorry if this seems a little basic but: What are the basic principles underlying good support design?

I live in an old (1850's) house so my ProAc speakers are in mahogany and my kit is on (unsatisfactory) Apollo supports meant for Cyrus-sized kit and fitted inside an old mahogany(1950s?) HMV cabinet - photo to follow on future post.

I am about to radically change the support system in a wonderfully homemade kinda way. Apollo steel legs are to go and I will rest the 6mm glass shelves on 3mm draught excluder (I kid you not) which on turn rests on hardwood supports fixed to inside of HMV cabinet. Each piece of equipment will sit on an Audiophile Base01 vibration platform which sits on the glass shelf.

I reckon in terms of isolation this will be top drawer, as the Base01s will do the bulk of the job and the foam excluder will absorb any residuals.

It's not granite or anything similarly dense... am I right in assuming that the purpose of supports is to isolate each piece of equipment from each other and from outside (vibrational) interference? Do dense/heavy supports and isolators like spikes/cones/platforms aim to achieve the same thing?

I'm doing this work over the festive period and will post photos and listening results, but any comments will be fed into SUPPORTS PROJECT PHASE II (?) which may mean replacing the Base01s with granite slabs or whatever if I am convinced I am missing something. Of course if anyone says "no, no, not mahogany!" or similar I may halt Phase I...

Earlier posts made me nosey about Mana supports so I visiterd the website and discussion forum. I note that they use glass shelves also, though I have to say I was not convinced that they had anything to offer which would justify what sometimes feels like a cult following... If the pro- and anti-Mana gangs want to exchange lively views then feel free but I'd be grateful if you would also take account of my own proposed approach.

Happy Christmas to all out readers!

 

This whole response is "as I see it" and "in my opinion". I might present something as fact that I see as fact, but others may not agree...

A hifi support has two functions. The first is mechanical support; holding the thing up, and any old table or whatever will do this. The second is mechanical isolation or coupling, with various little subtleties. To my mind, the ideal equipment support (not speaker support) will isolate the equipment from the floor (assuming that is what the support is based upon).

For this isolation to be effective, I consider two things to be required. The first is significant mass, the second is significant damping (energy absorbtion).

Why mass? Because the rack is having X amount of energy imparted to it from the sound waves in the room. Since, for a given volume and signal (eg a sine wave), X will remain constant, we can see that the kinetic energy, X, is equal to 1/2 * m * v * v (anyone who has done GCSE / O-level physics knows this). Since we've determined that X is constant (or at least is proportional to an external factor which is unaffected by anything we may do with regard to the equipment support), we have two variables to play with, m and v. v is the velocity with which our hifi component moves (or vibrates) due to the input of energy X. I believe in reducing this as far as possible. Obviously for constant X this means that the bigger we make m, the smaller v must be. Thus a heavier object vibrates less.

Why damping? Because although with a high mass we've reduced the magnitude of the vibration significantly, it still exists. We want to try to convert the energy from the kinetic form into something else (exactly what, we're not too bothered... however, chemical and electrical forms aren't easily practicable, so we tend to convert to heat). This requires some material that will cause such a conversion, and that is something like sorbothane, rubber, air, sand, etc.

To put all of that theory into practice, I constructed my own design of hifi rack. The frame is welded with solid steel cross-members and tubular steel uprights (25mm diameter rear, 50mm diameter front). And, upon delivery from the welding shop, it rang something dreadful. This is because it was fulfilling neither condition laid out above, with no absorbtion, and not a great deal of mass.

The first stage of the transformation was to add both mass and damping in the form of sand in the tubular uprights of the frame. Obviously sand weighs quite a bit, and the energy absorbtion arises from friction between the grains when you make them move (ie shake a tin that's half full of sand, and it will heat up). That helped a lot, but there was still some ringing.

However, that disappeared completely with the next stage, which is the 30mm thick granite shelves (around 17kg each), which sit on low-pressure inflated inner tubes on the solid steel cross members. There is just enough air in the tube for the granite to "float", and this absorbs a great deal of energy.

An analogy is to compare the ride of an air-suspended, 2200kg lexus LS to that of a 100kg gocart. The gocart is rigid and light (similar to a glass shelf), with no suspension, and you really feel every bump. With the lexus, you could be riding a magic carpet for all you can feel of the bumps.

However, I certainly think that there is plenty of room for homebrew experimentation in the area of supports, and wood certainly has some interesting properties for supports.

Let us know how you get on with your setup!

 

isaac,
you forgot the third and oft forgotten third purpose.... to provide denzsiens of internet chat forums with material for endless arguments about the benefits of various methods of support. the support manufacturers have succeeded so well with this aim that the mere mention of the m*** word has lead to bannings and vicious rivalries that have spilled over into real life running knife battles on brighton front.
the hi-fi support as the reason for middle eastern conflict is the subject of my dissertation which i hope will earn me a phd in sociological bollocks from the open university. aparently bush and blair are into hutter whilst saddam was a m*** guy... just goes to show.

cheers


julian

 

Mr Flash

Despite all the waffle one can read about equipment stands, the real truth is that no one really knows the answer. Mana, Fraim, Hutter, Quadraspire, Base and others all use different approaches and all sound slightly different.

If you have no racks at all, then the old ball bearing/nut/MDF board trick is a good begining and that will clean up your sound for less than £20.00. Also if you have a dodgy set of floor boards, slabs will help.

I spent 6 months demming racks, mainly in other peoples houses, but that is fraught will difficulty because they all had different kit and rooms etc. I settled for Hutter because it looked good (subjective) and gave a nuetral presentation of the music. Three weeks after I bought it, Naim released the Fraim which is even, in my opinion, better than Hutter.

Your ears are unique to you, so up to point, I would not listen to anyone elses recommendations.

Regards

Mick

 

I suppose that really the isolating principles are designed to...1)deal with the groundbourne vibrations, 2) airborne vibrations 3) other items on the rack's vibrations 4) the items own vibrations.

Racks seem to do that with some combination of 1) using mass 2) dampening/isolation materials 3) sympathetic resonance 4) draining/controlling the flow of energy

I dont think Ive missed anything!...but I probably have...

As has been said, there are many ways to skin a rabbit!

.... I suppose Id be asking myself questions like..... 1) Whats to prevent vibration coming through my sideboard, through the foam and through the wooden base to my hifi component? 2) whats the floor made of? will footfall etc make the hifi shake? 3) will the foam cause the internal vibrations of the item to decrease, increase, or drain away? etc etc

dont know if that helps any (probably not)!!

anyway, happy x-mas
Chris

 

No support systems war please - it's Christmas!

Thanks for all responses so far. Julian, I understand your cynicism but one of the things that might help to dispel some of the cr@p is to agree on some basic principles - like bottleneck's four vibration sources. We can differ on how to tackle each of course, and each might differ in importance to us depending on our own set-up, room, ears, etc, and each manufacturer might focus on addresing one over the other. I have no interest in either type of religious war - either fundamentalist "my M?n? is the only true faith, your Hutter is blasphemous and shall be cast into the darkness" OR atheist "all support is cr@p, just slap it on a shelf".... call me an inquisitive agnostic!

In response to Bottleneck's very pertinent questions:
(1) Audiophile Base01 vibration platforms (£99 each) seem to get very good reviews when used between equipment and just about any support system. I am relying on these to take out most of the ground-borne, rack-borne and item-itself-borne vibrations though I suspect only mass would tackle air-borne (maybe I'll just close the cabinet doors when listening
(2) floor is made of concrete, carpet-covered, so none of the footfall and other floorboard problems;
(3) I guess the foam is better than glass onto wood - it will either do zilch to the remaining vibrations or reduce them - there is no way I can it see it acting as any sort of amplifier.

All the best,

 

Re: Mr Flash

Correct.
I've said it before and I'll say it again now - one day you'll thank me.:knight:

There is no possibility of a consistent answer to the question of what is the best equipment support method without bearing in mind:

1. The type of floor and the mechanical coupling between floor, room and house.

2. The coupling (or isolation) of the speakers to the floor. We don't all use spikes and this interface has the major effect on the vibration feedback to the equipment.

I believe that unless these two areas are borne in mind there can be no reasoned debate on the subject and we'll continue to get the doctrinal, 'religious' flaming that we see so often. Meanwhile, I suggest a 'try it and listen' approach and I would venture that the approach you're taking could well bear fruit. Once you start, there's nothing to prevent you tweaking and improving it.

Airborne vibration is a separate issue and has to do with the individual resonant frequencies of various components, knobs (tee-hee!), etc. and, probably more significantly, the Helmholtz Resonator frequency of different equipment cabinets.

 

Re: Re: Mr Flash

May I just add that if you're going the isolation way (rather than coupling), there's a lot to be said for using superballs in doorstops. inverted superball/doorstop isolating device