In article , Powell
wrote:

"Jim Lesurf" wrote

My speakers have four spikes beneath them which makes it a pain to
move the speakers even slightly as the length of at least one
spike has to be adjusted to make all four rest on/in the floor.
(The floor is solid - maybe concrete - and not wood.)

"concrete"... is a very good vibration sink compared to wood, for
example.

What size/shape/structure/type of "concrete" do you have in mind, and
what do you mean by "sink"? Can you point pun me at measurements to
support what you say?

In theory, all things being equal (concrete's mass will convert more
sound energy to heat more efficiently as compared to wood which tends to
resonate.

Afraid that reads like a rather muddled set of assertions to me. Which "all
things" are you setting "equal"? What do you mean by "concrete's mass"? Do
you mean 'density', or what?

How does 'concrete' having 'mass' mean it disspates vibration more easily
than the same 'mass' of wood?

What about the question of coupling between the different mechanical
impedances which may mean that less energy transfers? etc, etc.

All solid structures have a tendency to 'resonate'. But since you still say
nothing about the structral sizes and shapes, nor the internal wave
impedances, velocities, or dissipation factors, nor how the coupling
depends on many factors, your assertion isn't one you have actually
explained.


Many high end speaker manufactures like Wilson Audio, B&W,
Egglestonworks and others construct speaker cabinets out of synthetic
compounds, stone, or aluminum for this reason., for example. Of course
in practice it is more a complicated subject because of Q value effects.

Meausrements... yes, I have data. What is your specific question?

Provide the specific measurements (and how you did them) that back up the
specific assertions you make above. We could then decide if your views are
supported by measurements you (or others) have made, nor not.

If this is a carpet and pad installation over concrete it is unlikely
that spikes will work anyway, IME.

"Work" means?...

For maximum effectiveness spikes should not be run through any type of
carpet interface (carpet/foam).

You have now traded one word (work) you didn't define for a phrase
(effectiveness) which you also haven't defined. What is your measureable
definition for these terms?

If you have high quality carpet, spikes just won't penetrate the
carpet/pad substrate.

Well, I do have spikes on one of the pairs of speakers I use. And I had no
trouble getting them to penetrate the thick carpet and underlay. However I
don't know that the spikes do much beyond stopping the speakers wobbling a
bit if I bump into them. However...

The problem here is as already referred to in this thread. That various
people make all kinds of confident assertions about how spikes/cones
'work'. But they often do so in vague and sweeping ways, providing no
evidence beyond assertions. And the 'reasons' they assert often conflict
with one another. This seems to apply both to the behaviour of spikes, and
the behaviour of the materials and objects they link.

Quality casters make a good alternative (measured reduction in
cabinet vibration) to speaker spikes, IME.

Ah. Thanks, can you give a URL for the measurements you are referring
to here?

I've not placed this data on the web.

OK. So you are just presenting your opinions without presenting any of your
(claimed) evidence. Thus no-one can tell if what you claim stands up, or
that your evidence actually supports your assertions. Nor, indeed, if you
actually have any evidence.

Since my background is in science and engineering, I do tend to prefer to
base my own conclusions on being able to assess measured evidence, and the
details of how those measurements were obtained. Given that consumer audio
is awash with 'technobabble' I tend to place more reliance on that than on
simply accepting assertions.

Thus far I am left with the feeling that your assertions do muddle up
different physical properties. This isn't unusual. Many people with no
serious background in physical science or engineering can confuse things
like 'strength' and 'rigidity', 'mass' and 'density', etc, etc. However if
you don't provide any measurements of your own, and can't even point to
ones by others that support your assertions, I can't reach an actual
conclusion. I can only decide that your opinions have not been given any
reliable basis upon which others can assess them.

FWIW I think Keith Howard did do some measurements on some of the effects
of 'spikes' a few years ago for HFN. I also think there are lists of values
of the relevant material properties in 'Structure-Borne Sound' by Cremer,
Heckl, and Ungar. I do have a copy of that[1] and the magazines. So I'll
have a look if I get a chance and see what the data indicates. BTW IIRC
materials like 'wood' and 'concrete' have ranges of material values that do
cover quite large ranges. Be interesting to refresh my memory on this when
I have a chance. :-)

Slainte,

Jim

[1] Cost a fortune and reads like the English is still in German. 8-] But
is packed with some interesting data and analysis. Recommended to anyone
with a serious interest in this topic who doesn't mind being faced with
some 'hard sums' maths. ;-

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