How hard should my balls be?
 

I'm in the process of chopping a nice little DD deck:

http://www.apah69.dsl.pipex.com/show/Chopper.JPG


Which is already much better since I removed the dodgy 'suspension' and
clamped it directly to a piece of, er, kitchen worktop - which has produced
a much richer and 'fatter' sound already, but I need some feet which will
work at least as well as (and look better than) two bath sponges and a
packet of Fusilli...??

Nick G has mentioned squash balls which, sitting in little wooden rings,
would work but I'm curious about wooden cones, which I can buy for a coupla
hundred quid or make for about 50p (still not decided...) - what I want to
know is which way up for best 'isolation' (energy dissipation) - points up
(from a concrete paving slab) or points down...??

Any Stress Engineers here? (Or I'll take the opinion of an ordinary engineer
who is at least a little bit wound up.... !! ;-)

How hard should my balls be?
 

On Wed, 27 Sep 2006 10:57:21 +0100, "Keith G"
wrote:


I'm in the process of chopping a nice little DD deck:

http://www.apah69.dsl.pipex.com/show/Chopper.JPG


Which is already much better since I removed the dodgy 'suspension' and
clamped it directly to a piece of, er, kitchen worktop - which has produced
a much richer and 'fatter' sound already, but I need some feet which will
work at least as well as (and look better than) two bath sponges and a
packet of Fusilli...??

Nick G has mentioned squash balls which, sitting in little wooden rings,
would work but I'm curious about wooden cones, which I can buy for a coupla
hundred quid or make for about 50p (still not decided...) - what I want to
know is which way up for best 'isolation' (energy dissipation) - points up
(from a concrete paving slab) or points down...??

Any Stress Engineers here? (Or I'll take the opinion of an ordinary engineer
who is at least a little bit wound up.... !! ;-)


Totally unstressed today - but here we go anyway.

Wooden cones wont dissipate any energy to speak of, whichever way up
you put them. They'll transmit every footstep and passing lorry. The
squash balls are a great idea though. A better idea than wooden rings
might be a pretty sheet of wood with holes drilled in appropriate
places, about half the size of the squash balls. Is that grey plinth
thing heavy? If it is then try to keep that above the squash balls -
sprung mass is what it is all about.

d

--
Pearce Consulting
http://www.pearce.uk.com

How hard should my balls be?
 

"Don Pearce" wrote


Totally unstressed today - but here we go anyway.


I will be less stressed when I've retrieved my credit card from the computer
shop in a little while from now! (Last minute, pre-closing dash for a new
router last night!!)

(That's *rooter* not 'rowter' as the bloke kept calling it!! ;-)



Wooden cones wont dissipate any energy to speak of, whichever way up
you put them. They'll transmit every footstep and passing lorry. The
squash balls are a great idea though.


But commonplace - I've already got squidgy feet on a couple of other decks
and they work just fine. I can do squidgy anytime, I wanted to explore
'solid shapes'. I don't have passing lorries (often) or footfalls to worry
about - a valve amp and concrete paving slab tame the rack fairly well and
its on a carpetted, concrete floor!

What I want to do is clamp mass to the turntable.

A better idea than wooden rings
might be a pretty sheet of wood with holes drilled in appropriate
places, about half the size of the squash balls.


Ooh, do I detect DIY leanings...?? :-)


Is that grey plinth
thing heavy?


It's all heavy.


If it is then try to keep that above the squash balls -
sprung mass is what it is all about.


No, taking springs out of the equation is what it's all about (this time
round, anyway)....

How hard should my balls be?
 

On Wed, 27 Sep 2006 11:45:01 +0100, "Keith G"
wrote:

If it is then try to keep that above the squash balls -
sprung mass is what it is all about.


No, taking springs out of the equation is what it's all about (this time
round, anyway)....



But springs are good for things like this unless you are absolutely
certain of the seismic stability of your setup. You need to find
somewhere that isn't on a tectonic plate for that and it can't be on a
rack either. At the very least you are begging for acoustic feedback
from the speakers if you go solid (and if you are, why do it via
wooden cones which can only introduce worse resonance problems, rather
than just bolt the ******* down?).

d

--
Pearce Consulting
http://www.pearce.uk.com

How hard should my balls be?
 

On Wed, 27 Sep 2006 11:45:01 +0100, "Keith G"
wrote:

But commonplace - I've already got squidgy feet on a couple of other decks
and they work just fine. I can do squidgy anytime, I wanted to explore
'solid shapes'. I don't have passing lorries (often) or footfalls to worry
about - a valve amp and concrete paving slab tame the rack fairly well and
its on a carpetted, concrete floor!

What I want to do is clamp mass to the turntable.

So why separate it with feet?

How hard should my balls be?
 

"Don Pearce" wrote in message
...
On Wed, 27 Sep 2006 11:45:01 +0100, "Keith G"
wrote:

If it is then try to keep that above the squash balls -
sprung mass is what it is all about.


No, taking springs out of the equation is what it's all about (this time
round, anyway)....



But springs are good for things like this unless you are absolutely
certain of the seismic stability of your setup. You need to find
somewhere that isn't on a tectonic plate for that and it can't be on a
rack either. At the very least you are begging for acoustic feedback
from the speakers if you go solid (and if you are, why do it via
wooden cones which can only introduce worse resonance problems, rather
than just bolt the ******* down?).


What, just flump it down?

(****, I never though of that.... ?? :-)

Anway, wanna look at my balls?

http://www.apah69.dsl.pipex.com/show/balls.JPG

:-)

(What were you expecting? ;-)

Those and two sponges cost 1.50 all in - I asked the blokey in the Handyman
shop (an Aladdin's cave....) if they were *sonically superior* to Shakti
Stones and he said 'Oh yiss, guv - honest'...!!

YHFL....

:-)

How hard should my balls be?
 

On 2006-09-27, Keith G wrote:

I'm in the process of chopping a nice little DD deck:

http://www.apah69.dsl.pipex.com/show/Chopper.JPG

Which is already much better since I removed the dodgy 'suspension' and
clamped it directly to a piece of, er, kitchen worktop - which has produced
a much richer and 'fatter' sound already, but I need some feet which will
work at least as well as (and look better than) two bath sponges and a
packet of Fusilli...??

Nick G has mentioned squash balls which, sitting in little wooden rings,
would work but I'm curious about wooden cones, which I can buy for a coupla
hundred quid or make for about 50p (still not decided...) - what I want to
know is which way up for best 'isolation' (energy dissipation) - points up
(from a concrete paving slab) or points down...??

I have tried out squash balls cut in half under certain bits of kit [1].

In a previous career in semiconductor devices, the group I worked in used
to mount vibration-sensitive kit on solid slabs which were suspended on
compliant air-filled rubber "springs". This certainly worked.

[1] I couldn't hear any difference with the half-squash-balls under
anything I had (but I don't use my Thorens/SME/AKG these days so I
didn't try that).

[2] Optical lithography kit which aligned wafer and mask to sub-micron
precision.

--
John Phillips

How hard should my balls be?
 

Keith G wrote

I'm in the process of chopping a nice little DD deck:

http://www.apah69.dsl.pipex.com/show/Chopper.JPG

Which is already much better since I removed the dodgy 'suspension'
and clamped it directly to a piece of, er, kitchen worktop - which
has produced a much richer and 'fatter' sound already, but I need
some feet which will work at least as well as (and look better than)
two bath sponges and a packet of Fusilli...??

Nick G has mentioned squash balls which, sitting in little wooden
rings, would work but I'm curious about wooden cones, which I can
buy for a coupla hundred quid or make for about 50p (still not
decided...) - what I want to know is which way up for best
'isolation' (energy dissipation) - points up (from a concrete paving
slab) or points down...??

Any Stress Engineers here? (Or I'll take the opinion of an ordinary
engineer who is at least a little bit wound up.... !! ;-)

Clamping the opposite of decoupling. Perhaps you could use clamps?

A thin layer of blu-tak or well-chewed gum under each corner should
spread the mass evenly and secure the deck against sideways forces
and, er, rocking couples.

Or bolt it down, as has been suggested, if you are inclined to worry
about high-frequency performance of blu-tak. Low frequencies won't be
a problem if the blu-tak is thin.

Cones don't dissipate energy unless they are squidgy. Squidgy cones
are unstable. Stiff cones dissipate compressive and sideways *forces*
quite well, if your objective is to raise something heavy above the
ground so it doesn't sway about. Think bridges, derricks, and the
like.

Generally pointy end up: the idea is to ensure that the cone is in
compression such that the supported weight, combined with relatively
small sideways forces, maintains the line of force from the point
within the boundary of the base, so every part of the cone is always
in compression, so the bridge doesn't fall over, even in a gale. This
assumes that the ground itself is stiff and that the bases cannot
slide, and also means that the supported weight doesn't need to be so
stiff, because the pointy ends cannot apply rocking couples to it, or
vice-versa. Also to relieve the points from the weight of the cones
themselves, and because they are easier to build that way because
otherwise it is hard to climb, even with a ladder. I guess that's why
the Pyramids are point up. In all these applications, the sharp end
should be effectively pin-jointed so whatever is resting on it can't
slide.

Just as cones spread force in one direction, they concentrate it in
the other. Hence they tend to make an effective pin-joint because the
point embeds itself under compression if the surface is relatively
soft. If you use them pointy-end down, as in spikes, then the bases
must be prevented from sliding. Whatever you are supporting must also
be structurally stiff.

Quite what this has to do with your application I don't know. It only
makes sense for big things, so you don't waste time and materials on
unnecessarily bulky supports, reduce forces from wind and/or tide, and
let ships through. For coupling to a hard surface, thin blu-tak is
better than spiking, and chewed gum is even better, although it takes
longer to run in.

Better still would be to embed the whole deck in cement. That would
relieve the bending forces on it between supports due to its weight.
Not good for cooling though.

cheers, Ian

How hard should my balls be?
 

On Wed, 27 Sep 2006 13:32:56 +0100, "Keith G"
wrote:


"Don Pearce" wrote in message
...
On Wed, 27 Sep 2006 11:45:01 +0100, "Keith G"
wrote:

If it is then try to keep that above the squash balls -
sprung mass is what it is all about.


No, taking springs out of the equation is what it's all about (this time
round, anyway)....



But springs are good for things like this unless you are absolutely
certain of the seismic stability of your setup. You need to find
somewhere that isn't on a tectonic plate for that and it can't be on a
rack either. At the very least you are begging for acoustic feedback
from the speakers if you go solid (and if you are, why do it via
wooden cones which can only introduce worse resonance problems, rather
than just bolt the ******* down?).


What, just flump it down?

(****, I never though of that.... ?? :-)

Anway, wanna look at my balls?

http://www.apah69.dsl.pipex.com/show/balls.JPG

:-)

(What were you expecting? ;-)

Those and two sponges cost 1.50 all in - I asked the blokey in the Handyman
shop (an Aladdin's cave....) if they were *sonically superior* to Shakti
Stones and he said 'Oh yiss, guv - honest'...!!

YHFL....

:-)

Well, squash isn't a word that comes to mind looking at those - don't
like the look of those shears either, especially in context :-(

d

--
Pearce Consulting
http://www.pearce.uk.com

How hard should my balls be?
 

"Don Pearce" wrote


Well, squash isn't a word that comes to mind looking at those - don't
like the look of those shears either, especially in context :-(


They ain't shears, they're scissors...

Right, in acknowledgement of the interest shown by your own good self, you
shall be the first to hear how this little experiment went:

First, you've seen my balls:

http://www.apah69.dsl.pipex.com/show/balls.JPG


Now, by means of a secret method, they are made up thus (note the interest
shown by the DLL who has nothing better to do):

http://www.apah69.dsl.pipex.com/show...&%20Friend.JPG

Here is the deck on the 'Spunj Feet' (which have just about the right amount
of give):

http://www.apah69.dsl.pipex.com/show/Spunj%20Feet.JPG

And now on the 'Bolly Feet':

http://www.apah69.dsl.pipex.com/show/Bolly%20Feet.JPG


A quick comparison (sighted, because I need help with the lifting/placement)
brought the following reaction from my resident, totally neutral 'Golden
Ears' - 'Wow! Much more 'airy' and tuneful!!'

??? ('Sonorous' was also said a little while afterwards! ;-)

Now, guess which way round that was...??

Comparisons not yet started in earnest and they will be done as 'blind' as
possible with anybody who is up for it......