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.... !! ;-)

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

"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)....

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

"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....

:-)

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

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?

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



Totally unstressed today - but here we go anyway.

Wooden cones wont dissipate any energy to speak of, whichever way up you
put them.

i became curious about the 'cones and spikes' some years ago. Looked at the
work on vibration in solid structure.

Three things emerged:

1) That with a cone there was no inherent reason for thinking one way up
was different to the other *unless* the materials/surfaces they seperated
have very different acoustic properties. In which case, those surfaces
determine what is going on anyway. (Here 'different' as in 'carpet' versus
'steel' rather the relatively minor differences between most solids
involved.)

2) That the actual shape doesn't matter much unless it caused plastic
deformation of the surfaces it contacts.

3) That oak had acoustic properties surprisingly similar to metals. So
choose oak if you like the look of it.

Oh, and,

4) The cones/spikes tend to transmit vibrations about as well as most
ofther shapes of similar overall size. They are all much smaller than the
wavelengths involved so tend to act as a 'lumped element'.

So if you want isolation/damping, then your deciding to go for squash balls
makes more sense. Oak cones may be prettier, though. :-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

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

"John Phillips" wrote in message
...
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).


I'm not the least bit surprised to hear it - I'm on a little 'trail' of my
own, atm....

What Thorens, btw...??



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


I had one of those once - unfortunately the wheels fell of it...

:-)