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Glens of Antrim

4 feet better than 3?

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Hi

Why do some manufacturers use 3 feet on their equipment instead of 4? And what do people feel is the most stable.

As a non scientist it seems a no-brainer that having ‘4’ supports would be inherently more stable than a tripod. My old Rega Planar 3 was certainly less stable than other decks I owned with quad feet.

BTW this was being debated on the Naim website. This poor bloke who said 3 was better than 4 was being flamed down as a heretic & non believer because if JV put 4 supports on his kit then, verily 4 it is.

GofA

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If you have any doubts about which is the most stable between 3 legs and 4 then do as I did and gentlyprod two loaded up racks in a hi-fi dealers and see which one sways around. The tripod stand swayed and actually twisted much to my horror whereas the four legged job was perfectly stable. Bear in mind too that the four legged variety was taller than the tripod stand.

So why make tripod stands? Less welding, quicker and cheaper to build ;)

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My Primare D30.1 Mk1 CD player has 4 feet and the newer Mk2 has 3 feet. Not sure if its any better though.

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As an engineer (civil/structural not electronic/electrical) - 3 points of support is ALWAYS preferable to 4.

Reason: This is known as Hambly's Paradox. Ask (most) people which is stronger - 3 or 4 legs on a table, they'll nearly always say 4 legs. Logically all the weight (mass) distributed four-ways rather than 3 means that less strength is required in each of the legs which has got to be better?

Uh - not always. If you put your table (or CD player) on a surface that is not entirely level it will rock. At some point two of the legs will be up in the air as the table rocks back and forth, at which point it is supported only by the other 2 legs on the ground. So the weight whichwas designed to bedistributed through 4 points of support (legs) is now only distributed through 2 points of support, effectively increasing the load by 100%.

If you only have three points of support, this CANNOT happen, the load is always distributed by the three points (but not necessarily equally obv.), and therefore determinable, and therefore can be designed. Anything less than 3 points of support obviously means the thing falls down.

If the three points of support are correctly designed, they will always be more stable. The clever bit is in the design of those three legs.

Camera tripods? Theodolites? Surveying levels?

Of course this is not the same as being level! Having set up a fair few levels and theodolites in my time, I can confirm why thy have three levelling screws and not four!

Sorry to get all logical on your ass, but them's the physical facts!

(waits to get shot down in flamessssssssss)

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penance wrote:

I think mainly 3 feet are preferable due to ease of levelling.

$ feet can be levelled aswell, just easier with 3.

wot he said

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RichardG wrote:

As an engineer (civil/structural not electronic/electrical) - 3 points of support is ALWAYS preferable to 4.

Reason: This is known as Hambly's Paradox. Ask (most) people which is stronger - 3 or 4 legs on a table, they'll nearly always say 4 legs. Logically all the weight (mass) distributed four-ways rather than 3 means that less strength is required in each of the legs which has got to be better?

Uh - not always. If you put your table (or CD player) on a surface that is not entirely level it will rock. At some point two of the legs will be up in the air as the table rocks back and forth, at which point it is supported only by the other 2 legs on the ground. So the weight whichwas designed to bedistributed through 4 points of support (legs) is now only distributed through 2 points of support, effectively increasing the load by 100%.

If you only have three points of support, this CANNOT happen, the load is always distributed by the three points (but not necessarily equally obv.), and therefore determinable, and therefore can be designed. Anything less than 3 points of support obviously means the thing falls down.

If the three points of support are correctly designed, they will always be more stable. The clever bit is in the design of those three legs.

Camera tripods? Theodolites? Surveying levels?

Of course this is not the same as being level! Having set up a fair few levels and theodolites in my time, I can confirm why thy have three levelling screws and not four!

Sorry to get all logical on your ass, but them's the physical facts!

(waits to get shot down in flamessssssssss)

I was talking about swaying and rocking within the rack itself,not with reference to the load bearing pointson the floor with using 3 legs.

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Indeed, but as I was typing my rambling missive, he beat me to it!

As far as wobbly racks go - that's nowt to do with 3 or 4 legs, it's to do with how well it's been designed and put together!

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RichardG wrote:

As an engineer (civil/structural not electronic/electrical) - 3 points of support is ALWAYS preferable to 4.

Reason: This is known as Hambly's Paradox. Ask (most) people which is stronger - 3 or 4 legs on a table, they'll nearly always say 4 legs. Logically all the weight (mass) distributed four-ways rather than 3 means that less strength is required in each of the legs which has got to be better?

Uh - not always. If you put your table (or CD player) on a surface that is not entirely level it will rock. At some point two of the legs will be up in the air as the table rocks back and forth, at which point it is supported only by the other 2 legs on the ground. So the weight whichwas designed to bedistributed through 4 points of support (legs) is now only distributed through 2 points of support, effectively increasing the load by 100%.

If you only have three points of support, this CANNOT happen, the load is always distributed by the three points (but not necessarily equally obv.), and therefore determinable, and therefore can be designed. Anything less than 3 points of support obviously means the thing falls down.

If the three points of support are correctly designed, they will always be more stable. The clever bit is in the design of those three legs.

Camera tripods? Theodolites? Surveying levels?

Of course this is not the same as being level! Having set up a fair few levels and theodolites in my time, I can confirm why thy have three levelling screws and not four!

Sorry to get all logical on your ass, but them's the physical facts!

(waits to get shot down in flamessssssssss)

Hi Richard,

As I said I'm a scientific ignoramus - my physics teacher begged me not to carry the subject beyond 3rd year, while my chemistry teacher threatened me with a bunsen burner up my darkest cavity :shock:- but if Hambly's Paradox is fire-proof why do bridges havefour legs not 3. Though I understand your point about the inadvisability of 2 wobbly legs - I think...

Andwhy do speaker stands have 4 spikes instead of 3?

Frank,

You are a cynic after my own heart :)

Totally off subject, I'm so pissed off with myself. As I have said, my system is in the attic - low sloping roof, joists, uneven floorboards. It's quite difficult finding the 'sweet-spot' for my Operas. But the thing is I can never leave well alone. So in a moment of weakness I thought I'd move the speakers slightly to see if I could firm up the soundstage -45 mins later the soundstageis buggered &thesibilance (sic) is worse than Jonathon Woss without his false teeth. I am so fucking stupid :grrr:

Off to bang his head off the wall, GofA

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My Jamo Tripos rack has 4 spikes, two of which are so close together at the "apex" as to really be considered 1 leg.

wobbles all over the place like a fat cows arse :shock:

which just proves that 4 legs pretending to be three is the worst of all :D

need to upgrade it soon (one of those four legged quadraspires looks nice)

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was considered the norm not that long ago to always use 3 blods of blu tack, not 4 under your spks cos of what Richard said. With which I agree. Also agree that internal wobbles just mean crap build quality. In nature, I think I'm right in saying that the hexagon is one of the commonest rigid structures (honeycomb for example) and a hexagon is of course just 5 triangles joined together... buckminster fuller used these principles to create the geodisic dome a simple but very rigid thing ... a bit like.....:?

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In Nature an science a tripod is usually more secure, but usually used with a structure that had a realtively wide base, and low centre of gravity, the problem I feel with tripods in hifi is the shapes of the boxes, and their weight distribution, speakers are often tall and heavy at the top, this is not a problem if a force is exerted towards one of the points, however half way between two points and push, and it's often not stable at all. With children around, I personally will allways settle for 4 points.

The best thing I find with 3 legs with respect to Hifi is it's asy to get a platform not to rock, with 4 points this is harder but no means impossible, best to get levelish on 3 points, and then lower the 4th poiint till it touches ground.

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GofA

Indeed!

Bridges and stuff don't need to be stiff / rigid (if fact it's essential that they aren't). With all the applied forces they sustain (cars, wind, water, thermal) they need to be flexible otherwise they just break. So the stiffness requirement becomes less of an issue.

As far as why speaker stands and wotnot having four spikes not three - I dunno...maybe speaker stand engineers are not as clever as civil engineers (mieow!!!)

"My Jamo Tripos rack has 4 spikes, two of which are so close together at the "apex" as to really be considered 1 leg.

wobbles all over the place like a fat cows arse :shock:

which just proves that 4 legs pretending to be three is the worst of all :D"

GENIUS! Ever thought of a career in engineering?

Dicky

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