advertisement


Why Four Feet?

linnfomaniac83 said:
I think he was questioning why manufacturers tend to use four feet as opposed to three, and as far as I can see, it's because it's harder to knock kit over with four feet, at least where speakers are concerned.
Click to expand...
Precisely, as with many things hifi, it's convenience, plus the fact, many have no idea about the subject, those who do, usually act accordingly when designing the equipment.
Sticking big blobs of bouncing rubber under a cd player is hardly ideal isolation.

Plus, of course, the after market men would be out of a job :D
It's why most stick kettle leads in the box, price & convenience.....oooops :)
 
AndrewM said:
They are the same thing really, see stable v unstable equilibrium. The real advantage of the tripod arrangement is not that it is more stable (4 legs is more stable than 3, and 5, eg the office chair, is even better) but that is is self levelling.
Click to expand...
4 legs is no more stable, if the force is coming from above, 3 works best, in terms of hifi, the force is always coming from above, 3, 4, 5 or 10 legs will not stabilise a force from the side, all will knock over, but again, not the point.

The force will hit at a point of contact at precisely the same time with 3 legs but not with 4, even if meticulously levelled, there will always be room for movement, not with 3, it is physically impossible when the force is coming from above, it makes no odds where the weight is distributed in the equipment (some are weighted heavily to one side due to transformers etc) with 4, the weight can tip very slightly, as long as the triangle is set out centrally, it will stabilise.

You need to think less about convenience & more about how weight & force is distributed when placing an object on a solid mass, where the object is designed to sit without being kicked, or prodded or whatever, this is all meaningless where hifi equipment is concerned. I mean, who the hell leans on a cd player or amp when playing music?? not to mention speakers or stands, it's a point being made, which has no significance when sitting listening to music.
Forget sideways force, gravity travels down, this is the only force which matters in this instance & the only arrangement that ensures all points of force arrive precisely at the same time is the tripod arrangement, there is no room for error with this arrangement.
 
jobseeker said:
Sorry Ragaman - don’t understand what you’re asking. However, it’s quite simple. The ones with three feet tip to one side if pressure is applied in particular places along the top edges. The ones with four feet do not
Click to expand...
Why would such a force be applied to a cd player, amp, speakers, you have missed the point, maybe the above post may help. The last paragraph in particular.
 
A very good reason that some electronic components might need four feet is that there is often very uneven weight distribution (such as a heavy toroid offset to one side).
 
Ragaman said:
Why would such a force be applied to a cd player, amp, speakers, you have missed the point, maybe the above post may help. The last paragraph in particular.
Click to expand...

Have you never heard of little hi-fi destroyers on 2 legs? - sometimes called "children" - in addition to the ability to pull the heaviest speaker on top of themselves they can destroy a tweeter with a single exploratory poke or twist a turntable arm quicker than you can say Linn LP12.
 
Surely 3 feet is less stable than 4 feet UNLESS the object that you are trying to support sits within then perimeter of the triangle. Once you go outside that perimeter, you create an overhang that will cause a turning moment. In the real world, most 4 legged equipment support, whether its feet or shelves, are larger in perimeter than the kit they support, so are stable. In most 3 feet or legged support designs, this is not so. This argument about only downward force is gravity is rubbish. There are turning moments involved as well, caused by the uneven distribution of hifi kit weight as more than one contributor has already suggested. Test it for yourself. Get an empty shoebox, put it on 3 egg cups, 2 at the back in each corner one in the middle at the front. Now place a can of baked beans in the front left corner...shoebox will topple due to turning moment. Of course, I haven't tested this with other varieties of tinned food...;)
 
Vinny said:
My original point was quite simply that anything (that is not subject to collision with anyone or anything), absolutely cannot rock/vibrate if supported on three points, because, as I said originally, 3 points define a plane and only one plane (unless the three points are in one line), so all of the faff involved in getting four spikes set into one plane disappear - you could put a 3-spiked speaker stand on anything, as rough as you like, and it will still be stable in terms of rocking movement. Try a 4-spiked stand on a rough cast concrete floor with tamping marks...............................
Somewhere online, if anyone needs reminding, will be the set-up instructions for Mana tables and supports, including all the tapping and ringing that goes on to try to get four points to sit in the same plane (the plane of one side of one of the shelves).
Click to expand...
I agree that loudspeakers with three support points are easier than those with four. They will stand without any adjustment and not rock.

However:
  • Three-point supported loudspeakers with small footprint may need "outrigger" feet to make them adequately resistant to toppling. There's little in my home to create a risk of toppling. However other people do have risks at home and manufacturers have to consider all of their potential customers.
  • Outrigger feet low down by the floor may create a trip hazard for the clumsy (which includes me).
  • You still ought to properly level three-point loudspeakers on concrete floors having the characteristics you describe. So some adjustment is good anyway - typically using a circular spirit level. It is still simpler on three supports than on four.
  • Nevertheless, four supports is, IMHO, no significant extra difficulty with the same circular spirit level. The final most sensitive adjustment to get minimal rocking on one diagonal axis is pretty trivial even if there must be some small residual rocking when there's no compliance to work with. But my experience is that minimizing that takes little effort, on loudspeakers at least. I have never needed to do it on other kit.
They both have advantages and disadvantages. That's why we see both types in the market.
 
That s
diybry said:
three feet are less prone to rocking as previously stated, but are easier to knock over.
The solution, to me, is to have three feet which contact the floor, and two shorter feet which don't quite contact the floor, in the position where the 'missing' two of the four feet would be.
Result- stable platform which cannot be easily knocked over.
Click to expand...

That suggestion is way too sensible !!
 
Ragaman said:
4 legs is no more stable, if the force is coming from above, 3 works best, in terms of hifi, the force is always coming from above, 3, 4, 5 or 10 legs will not stabilise a force from the side, all will knock over, but again, not the point.

The force will hit at a point of contact at precisely the same time with 3 legs but not with 4, even if meticulously levelled, there will always be room for movement, not with 3, it is physically impossible when the force is coming from above, it makes no odds where the weight is distributed in the equipment (some are weighted heavily to one side due to transformers etc) with 4, the weight can tip very slightly, as long as the triangle is set out centrally, it will stabilise.

You need to think less about convenience & more about how weight & force is distributed when placing an object on a solid mass, where the object is designed to sit without being kicked, or prodded or whatever, this is all meaningless where hifi equipment is concerned. I mean, who the hell leans on a cd player or amp when playing music?? not to mention speakers or stands, it's a point being made, which has no significance when sitting listening to music.
Forget sideways force, gravity travels down, this is the only force which matters in this instance & the only arrangement that ensures all points of force arrive precisely at the same time is the tripod arrangement, there is no room for error with this arrangement.
Click to expand...
You are confusing stability with “wobbliness” an unstable object isn’t one that wobbles, it is one that will fall over easily if it is pushed from any direction. A speaker balanced on even a single spike won’t wobble and a directly downwards force on it won’t move it, but it is highly unstable as just a slight push either side will topple it over. Of course more legs will stabilise it, think of the stabilisers on a child’s bike.
 
Vinny said:
I can see that there are rather few engineers, physicists or applied mathematicians here.................................... I can also see that, to me, an AMAZINGLY large number of people expect speakers in particular to get the occasional "swipe".

My original point was quite simply that anything (that is not subject to collision with anyone or anything), absolutely cannot rock/vibrate if supported on three points, because, as I said originally, 3 points define a plane and only one plane (unless the three points are in one line)
Click to expand...

As an (ex-) engineer/physicst who lives in the real world I find that objects like speakers *do* get the occasional "swipe". In my case my wife has epilepsy. On one occasion I was - after caring for her - able to confirm that a QUAD 988 can make quite a scar on the plaster of the wall if pushed. Fortunately she and the speaker were OK, but a corner of the speaker gashed the plaster down to the brickwork.

Other people may have children or large pets, or simply stumble.

The distinction here is one I pointed out. Given an absence of external forces, 3 point systems can be inherently stable. But given the reality of external forces, 4 feed provide a better margin of resistance to toppling - thus provide more stability in some real world cases.

In addition: In the real world, supports and what they stand on have some elasticity. This means that an object *can* stand with more than four supports in contact with the floor.
 
I propose to use a design that combines the advantages of 3 and 4 foots.

In the front part you can use traditional supports, for example, 2 foots. In the back part, on the side of the lateral foots, install auxiliary supports of arbitrary shape, slightly shorter than the main foots, for example cubes of solid foam, glued to double-sided tape in place of traditional 2 hind foots.
The main, the third foot - in the right place, between the auxiliary ones.

At installation, the device is installed first on 4 foots - two, main and two auxiliary ones.

Then, the thrird foot is unscrewed, so that the auxiliary foots do not touch the floor a bit.

And at the same time the auxiliary foots prevent the device from accidentally overturning, as when installing on 4 foots.
 
@e53 You’re describing a variation of outriggers. Just keeping the outriggers within the overall footprint of the unit.

Adds some cost though, and may not be aesthetically pleasing in all circumstances.
 
It really amazes me how many people are prepared to give an opinion based on intuition or speculation.

It's really not hard to test and after comparing in various systems I concluded that four feet is demonstrably and repeatably better than three.
 
My Triangle speakers have five spikes... :p

Four are on an outrigger arrangement, but are set back a little too far for ultimate stability. There is a fifth large spike, centrally placed at the front of the baffle. My assumption has always been that it is basically a three spike arrangement between the larger front spike and rear pair, while the 'other' front pair are set slightly short, and come into play if the loudspeaker is rocked.

It works OK on carpet but I wouldn't like to faff with it on a hard floor.

I remember putting Goodmans Magisters on bricks, in simpler days...
 
AndrewM said:
You are confusing stability with “wobbliness” an unstable object isn’t one that wobbles, it is one that will fall over easily if it is pushed from any direction. A speaker balanced on even a single spike won’t wobble and a directly downwards force on it won’t move it, but it is highly unstable as just a slight push either side will topple it over. Of course more legs will stabilise it, think of the stabilisers on a child’s bike.
Click to expand...
Dear lord

Yes, think about that one for a minute, has it dropped yet?

Hint, how many stabilisers are placed at the front?


A stabiliser is not a support, it is a psychological tool.
 
You must log in or register to reply here.


advertisement


Back
Top