Tennis Ball isolators
Croak
Has anyone tried this isolation technique of cutting a tennis
ball in half and sticking it beneath a component? I noticed
the rubber is remarkedly similar to some of the expensive
"feet" I've seen around. Any opinions?
Kenneth P Braman
Croak (cr...@haven.ios.com) wrote:
: Has anyone tried this isolation technique of cutting a tennis
: ball in half and sticking it beneath a component? I noticed
: the rubber is remarkedly similar to some of the expensive
: "feet" I've seen around. Any opinions?
My tennisball rumor was a few people using whole tennis balls under
subwoofers to bring them a bit off the floor and tighten the bass.
[shrug]
< Paul Braman >< The X-Files >
< thx...@grove.ufl.edu >< THX / TMH >
< find me on IRC in #friends as THX >< Aeon Flux >
< http://grove.ufl.edu:80/~thx1138 >< Stereophile >
Marinade
I have a friend who has sawed (cut) raquet balls in half and done the same
thing. Swears by it. I think what one needs to do is to sometimes look
past the audiophile jewlery aspect of over the counter tweaks and applie
some common sense form follows function. Too many times I've walked into
friends audio situations and found them listening to tweak traps in lieu
of music. But back to your original question, I've yet to hear an
isolated one-tweal-fits-all. You may have to fine tune your isolation
issue with a combination of stands, spikes, rubber or a bottle of good
wine and recorded music to match.
Jim T
Steve Ellis
Croak wrote:
>
> Has anyone tried this isolation technique of cutting a tennis
> ball in half and sticking it beneath a component? I noticed
> the rubber is remarkedly similar to some of the expensive
> "feet" I've seen around. Any opinions?
I've heard of people using "water closet gaskets" as isolators. I
picked up 4 ( for less than $8! at a plumbing supply co.), but haven't
had time to try them yet. They are about 3 inches across and an inch
or two deep. This is the gasket that goes from the tank to the "bowl"
NOT the waxed gasket.
It seems like it should work quite well. It is firm yet vibration absorbent.
Steve Ellis <"mailto:se...@ix.netcom.com">
Scott Weinmann
Uh, uh.
Tennis balls, raquet balls, ping pong balls, handballs are all made to
do what, class? RECEIVE, STORE-MOMENTARILY, and then RELEASE ENERGY.
That is why all of the above balls bounce. What you all have figured
(incorrectly, I might add) is that function follows form. Well, it is
not the shape, you knuckleheads (;-)), but the material that matters.
At the Stereophile show this weekend, AudioPrism was demonstrating the
difference between a hammer falling on a Sims Navcom vibration damper
(hammer bounced..) and their AudioPrism IsoPoints (sic?).
When I brought the little AudioPrism balls and cups home and opened
them up, my daughter started immediately playing with them. I did the
hammer demo with my wife, too.
When I asked my daughter if the balls bounced, she threw one to the
floor, and there it stayed. Like a lead balloon. Not a bounce. Not
a micron. Complete and utter absorbsion of the energy (actually,
dissipated as heat, I believe..)
Now isn't that more or less what we are after when we contemplate
putting something beneath our precious components?
Bouncing up and down is not my idea of "taming resonances".
Ian Gray
Scott Weinmann wrote:
> Tennis balls, raquet balls, ping pong balls, handballs are all made to
> do what, class? RECEIVE, STORE-MOMENTARILY, and then RELEASE ENERGY.
>
> That is why all of the above balls bounce. What you all have figured
> (incorrectly, I might add) is that function follows form. Well, it is
> not the shape, you knuckleheads (;-)), but the material that matters.
Hmm.. I don't think you you will find that a tennis ball cut in half will
bounce very well :-).
After all it is the TRAPPED air that acts as the spring.
But obviously complete energy absorption is preferable to any kind of
bounce.
Rgrds Ian.
Richard D Pierce
In article <4ovajb$e...@agate.berkeley.edu>, Scott Weinmann
<sco...@interramp.com> wrote:
>Marinade wrote:
>> I have a friend who has sawed (cut) raquet balls in half and done
>> the same thing. Swears by it. I think what one needs to do is to
>> sometimes look past the audiophile jewlery aspect of over the
>> counter tweaks and applie some common sense form follows function.
>> Too many times I've walked into friends audio situations and found
>> them listening to tweak traps in lieu of music. But back to your
>> original question, I've yet to hear an isolated one-tweal-fits-all.
>> You may have to fine tune your isolation issue with a combination
>> of stands, spikes, rubber or a bottle of good wine and recorded
>> music to match.
>Uh, uh.
I smell an "explanation" coming, watch out...
>Tennis balls, raquet balls, ping pong balls, handballs are all made to
>do what, class? RECEIVE, STORE-MOMENTARILY, and then RELEASE ENERGY.
Wrong, no sit down and let the teacher teach.
>That is why all of the above balls bounce. What you all have figured
>(incorrectly, I might add) is that function follows form. Well, it is
>not the shape, you knuckleheads (;-)), but the material that matters.
First, the primary restoritive force force in tennis balls and such is
the compression and relaxation of the air inside the ball. Cut the
ball in half, or even punch a hole in it, and the behaviour of the
ball changes rather dramatically, simply because you've lost the
primary mechanical reactance: the compressibility of air. The rubber
the ball is made out of is a rather lossy substance, and that is the
primary reason the ball does not bounce forever. Energy is lost
through friction in flexing the rubber and dissipated as heat.
>At the Stereophile show this weekend, AudioPrism was demonstrating the
>difference between a hammer falling on a Sims Navcom vibration damper
>(hammer bounced..) and their AudioPrism IsoPoints (sic?).
An in=mpressive demonstration, and one which is, in and of itself,
pretty damned meaningless. It's possible to build a system that has
little or no mchanical loss which accomplishes precisiely the same
result.
>When I asked my daughter if the balls bounced, she threw one to the
>floor, and there it stayed. Like a lead balloon. Not a bounce. Not
>a micron. Complete and utter absorbsion of the energy (actually,
>dissipated as heat, I believe..)
Given a resiliant surface to bouce against, it's possible that the
surface is doing all the dissipation, NOT the ball. We've still
demonstrated nothing.
>Now isn't that more or less what we are after when we contemplate
>putting something beneath our precious components?
Answer: no. We are looking for isolation, and pure mechanical
resistance are NOT necessarily good at isolating, clever Audioprism
science-fair demonstrations notwithstanding.
>Bouncing up and down is not my idea of "taming resonances".
It's because your ideas are at odds with physical reality. Contrary to
the claims of clever marjeteers, devices that simply exhibit simple
frictional mechanical losses are not could isolators. They may
attenuate somewhat (and can only do so if they flex a great deal), but
that's it.
The use of a springy (mechanically reactive) suspenseion can do a fa
better job because the combination of the compliance of that
suspenseion and the suspended mass do, indeed, form a resonance, but
the other attendant property is that the combination also forms a 2nd
order mechanical low-pass filter whose cutoff frequency is essentially
that of the resonant frequency. As the external stimulus frequency
increases above that resonance, the isolation provided by that filter
increases as the square of the frequency. In a simple mechanical
resistance, the isolation is small (assuming the kinds of materials
that people are selling, because they are stiff and don't flex much)
and constant with frequency. Further, the fact that there is a measure
of mechanical stiffness means they DO form a mechanical low-pass
filter, but at a MUCH higher frequency, reducing their isolation
properties even further.
Okay, you can now entertain the class again.
[ Dick, be nice! -- The Principal ]
--
| Dick Pierce |
| Loudspeaker and Software Consulting |
| 17 Sartelle Street Pepperell, MA 01463 |
| (508) 433-9183 (Voice and FAX) |
mobius
Scott Weinmann <sco...@interramp.com> wrote:
> Tennis balls, raquet balls, ping pong balls, handballs are all made to
> do what, class? RECEIVE, STORE-MOMENTARILY, and then RELEASE ENERGY.
>
> That is why all of the above balls bounce. What you all have figured
> (incorrectly, I might add) is that function follows form. Well, it is
> not the shape, you knuckleheads (;-)), but the material that matters.
Squash balls, on the other hand, especially the "yellow dot"
softballs, are inherently dead. As soon as I break a couple of these,
I may give them a try under my turntable -- I'm not so depraved as to
cut up perfectly good squash balls for this purpose.
Another type of ball that seems fairly dead is the kind that comes
inside a computer mouse. Anyone tried these? It seems to me that
these might do a better job of keeping your equipment level than
larger devices.
Under Audio Alchemy peripherals or other lightweight gear, those
little foil condiment packets might work very nicely.
marivic canlas salamat
Dick Pearce wrote:
>The use of a springy (mechanically reactive) suspenseion can do a fa
>better job because the combination of the compliance of that
>suspenseion and the suspended mass do, indeed, form a resonance, but
>the other attendant property is that the combination also forms a 2nd
>order mechanical low-pass filter whose cutoff frequency is essentially
>that of the resonant frequency. As the external stimulus frequency
>increases above that resonance, the isolation provided by that filter
>increases as the square of the frequency. In a simple mechanical
>resistance, the isolation is small (assuming the kinds of materials
>that people are selling, because they are stiff and don't flex much)
>and constant with frequency. Further, the fact that there is a measure
>of mechanical stiffness means they DO form a mechanical low-pass
>filter, but at a MUCH higher frequency, reducing their...
I would like to relate alittle story that is kinda related to what DP
wrote, an accasion that presented itself while my family had to be out
of town for several weeks, and I had the bedroom all to myself (no
kids). I was feeling a little lonely so I hooked up some left-over,
now-in-the garage components I have (Adcom amp, homemade Radio Shack
attenuator, Sony CD/LD player, Celestion 3, mod.), and set them,
except the speakers, on my daughter's bed. Imagine my surprise when I
heard the crystal-clear, highly musical sound that I heard which in
some ways were better than my main system (which has tubes)! Now I
know that listening in the near field (about 5 feet helped), but I
realized that something was working its magic on this system, and I
surmised that its the mattress and its attendant coils/springs. Just
to satisfy my curiosity, I hauled components from my main system one
by one, and the system got even better. I even tried combinations that
I know from past experiences will bring an edgy sound, and you guessed
it, it didn't. To sum the sound I got from the system-on-the-mattress,
it was relaxed, detailed, and very musical, like the noise floor
becoming non-existent. Has anybody tried this, or accidentally
stumbled on it? RS
|
pat james
[ quoted text deleted -- jwd ]
I found the small bicycle tire tube a better cheap isolation fix as
you can "tune" it for mass of the equipment you are trying to isolate.
Scott Weinmann
[ Comments to the moderators deleted. -- jwd ]
Now, if I may retort:
Scott: Uh, uh.
Dick: I smell an "explanation" coming, watch out...
Scott: Tennis balls, raquet balls, ping pong balls, handballs are all
made to do what, class? RECEIVE, STORE-MOMENTARILY, and then
RELEASE ENERGY.
Dick: Wrong, no sit down and let the teacher teach.
Dick, if you are the teacher, my kids are in some serious trouble! If
a tennis ball doesn't "RECEIVE, STORE-MOMENTARILY, and then RELEASE
ENERGY", then what the hell is it doing when it is struck? The
kinetic energy received by the ball when it is struck by the raquet is
converted into stored kinetic energy, which is then released, (along
with some heat through friction losses, of course, or a "super-ball"
would bounce forever.)
That is why I wrote the following, and if you take exception to the
following statement, you are fired as "teacher"....
>> That is why all of the above balls bounce. What you all have
>> figured (incorrectly, I might add) is that function follows form.
>> Well, it is not the shape, you knuckleheads (;-)), but the material
>> that matters.
> First, the primary restoritive force force in tennis balls and such
> is the compression and relaxation of the air inside the ball. Cut
> the ball in half, or even punch a hole in it, and the behaviour of
> the ball changes rather dramatically,
Well, actually, not that dramatically. If I drop a hammer on half a
tennis ball, the hammer bounces....
> simply because you've lost the primary mechanical reactance: the
> compressibility of air. The rubber the ball is made out of is a
> rather lossy substance, and that is the primary reason the ball does
> not bounce forever. Energy is lost through friction in flexing the
> rubber and dissipated as heat.
>> At the Stereophile show this weekend, AudioPrism was demonstrating
>> the difference between a hammer falling on a Sims Navcom vibration
>> damper (hammer bounced..) and their AudioPrism IsoPoints (sic?).
> An impressive demonstration, and one which is, in and of itself,
> pretty damned meaningless. It's possible to build a system that has
> little or no mchanical loss which accomplishes precisiely the same
> result.
Dick, Dick, Dick. You and Bob at HP must spend a lot of time at "the
bench" together. Don't you get it, yet? I am a consumer. I am not
looking to "build a system", but rather to "buy" (for $35) something
that will tame the vibrations being manifested from within my
components..
>> When I asked my daughter if the balls bounced, she threw one to the
>> floor, and there it stayed. Like a lead balloon. Not a bounce. Not
>> a micron. Complete and utter absorbsion of the energy (actually,
>> dissipated as heat, I believe..)
And you even take issue with the above statement?
(Dick Says:)
> Given a resiliant surface to bouce against, it's possible that the
> surface is doing all the dissipation, NOT the ball. We've still
> demonstrated nothing.
Dick, My kitchen floor is not resilient. It is made of ceramic tile.
Hard as a rock. No give what-so-ever. And therefore, we have
demonstrated EVERYTHING! The floor being almost 100% non-resiliant
dissapated NOTHING (or damn close to nothing..), while the IsoBearing
ball dissipated ALL of the kinetic energy of its falling, accelerating
mass.
(Scott wrote:)
>>Now isn't that more or less what we are after when we contemplate
>>putting something beneath our precious components?
> Answer: no. We are looking for isolation, and pure mechanical
> resistance are NOT necessarily good at isolating, clever Audioprism
> science-fair demonstrations notwithstanding.
Aha!! Your fatal mistake! You see, Dick, you are an engineer (quite
obvious to the rest of us by now) and I am a salesman. What you
didn't do that any salesman (or doctor) could have told you to do, was
ask the question, "What are you trying to accomplish?"
Had you asked that question, instead of assuming (you know what
happens when you assume... ;-))you would have discovered that I am
not looking to ISOLATE my components. I was looking for an "Energy
Sink", for lack of a better term, to dissipate microvibrations
emanating from WITHIN my components (stuff like transformer hum, CD
transport aberrations, etc.)
So, I was not looking to isolate (from footsteps and the like..) but
rather to dissipate, and THAT is what these IsoBearings do!
(Dick wrote:)
> The use of a springy (mechanically reactive) suspenseion can do a fa
> better job because the combination of the compliance of that
> suspenseion and the suspended mass do, indeed, form a resonance, but
> the other attendant property is that the combination also forms a
> 2nd order mechanical low-pass filter whose cutoff frequency is
> essentially that of the resonant frequency. As the external stimulus
> frequency increases above that resonance, the isolation provided by
> that filter increases as the square of the frequency. In a simple
> mechanical resistance, the isolation is small (assuming the kinds of
> materials that people are selling, because they are stiff and don't
> flex much) and constant with frequency. Further, the fact that there
> is a measure of mechanical stiffness means they DO form a mechanical
> low-pass filter, but at a MUCH higher frequency, reducing their
> isolation properties even further.
Dick, do you think you are explaining anything here? You inability to
communicate with people other than engineers disqualifies you as
"teacher". Teachers need to be able to describe new concepts without
confusing the audience or assuming that they know more than they do.
A "2nd order mechanical low-pass filter whose cutoff frequency is
essentially that of the resonant frequency. As the external stimulus
frequency increases above that resonance, the isolation provided by
that filter increases as the square of the frequency". What the hell
are you talking about?
(Dick wrote:)
> Okay, you can now entertain the class again.
Class entertained.
Your class clown,
Scott
thei...@usa.pipeline.com
'Scott Weinmann <sco...@interramp.com>' wrote:
>Dick, if you are the teacher, my kids are in some serious trouble! If
>a tennis ball doesn't "RECEIVE, STORE-MOMENTARILY, and then RELEASE
>ENERGY", then what the hell is it doing when it is struck? The
>kinetic energy received by the ball when it is struck by the raquet is
>converted into stored kinetic energy, which is then released, (along
>with some heat through friction losses, of course, or a "super-ball"
>would bounce forever.)
above explanation has a few glaring errors. The ball has a certain
amount of kinetic and potential energy while in flight, then when
struck with the racket, essentially converts kinetic to potential
energy through compression of the rubber and air as well as the racket
strings, and then back into kinetic energy upon expansion and reaction
of the strings *minus* the heat through friction losses. The motion
of the ball is governed by the laws of momentum, the racket being the
much heavier item, moving much faster, thus the ball is now moving in
the opposite direction.
>Well, actually, not that dramatically. If I drop a hammer on half a
>tennis ball, the hammer bounces....
Actually, what you just stated is that since the hammer bounces, then
the rubber is a fairly elastic material, and not much good for
absorbing vibrations. However, have you ever tried to play with a
tennis ball that has had a pinhole in it? Have you ever heard of a
"dead" ball? Dick is quite right.
>>> When I asked my daughter if the balls bounced, she threw one to the
>>> floor, and there it stayed.
>(Dick Says:)
>
>> Given a resiliant surface to bouce against, it's possible that the
>> surface is doing all the dissipation, NOT the ball. We've still
>> demonstrated nothing.
>
>Dick, My kitchen floor is not resilient. It is made of ceramic tile.
>Hard as a rock. No give what-so-ever.
So how is Dick to know what floor you have? I just dropped a 3lb
steel ball onto my nice Heriz rug, and it didn't bounce. Come to
think of it, maybe scraps from an oriental rug repair shop might be
good absorbers, as well as decorations and pretty good acoustic
absorbers! Hey, a new product! ;)
>Had you asked that question, instead of assuming (you know what
>happens when you assume... ;-))you would have discovered that I am
>not looking to ISOLATE my components. I was looking for an "Energy Sink"
Yes, but Dick gave you a good example of a much better system than the
pure mechanical resistance that you have been describing. And your
example is also an isolator, despite what misconception you might have
about its function. You describe an isolator that is a simple
mechanical resistance (absorbtion), yet a more effective version would
be as Dick described below.
>So, I was not looking to isolate (from footsteps and the like..) but
>rather to dissipate, and THAT is what these IsoBearings do!
See above.
>Dick, do you think you are explaining anything here? You inability to
>communicate with people other than engineers disqualifies you as
>"teacher". Teachers need to be able to describe new concepts without
>confusing the audience or assuming that they know more than they do.
>A "2nd order mechanical low-pass filter whose cutoff frequency is
>essentially that of the resonant frequency. As the external stimulus
>frequency increases above that resonance, the isolation provided by
>that filter increases as the square of the frequency". What the hell
>are you talking about?
Okay, do you know what a crossover is? Let's make this really simple.
A 2nd order crossover for a woofer is simply an electrical "low-pass
filter whose cutoff frequency is essentially that of the resonant
frequency. As the external stimulus frequency increases above that
resonance, the isolation provided by that filter increases as the
square of the frequency." Sure, it would have been simpler to say
it's a mechanical analogy to a 2nd order woofer crossover, but you
seemed to have a fairly good grasp of technical terminology before, so
a bit more detailed description was not out of order.
Cheers!
Todd Jenkins
Project Engineer - EV/Altec Lansing
The opinions expressed herein do not represent those of EV/Altec Lansing.
Aschaub
thei...@usa.pipeline.com writes:
>>Well, actually, not that dramatically. If I drop a hammer on half a
>>tennis ball, the hammer bounces....
>
>Yes, but a hammer also bounces when you drop it on a slab of concrete.
>Actually, what you just stated is that since the hammer bounces, then
>the rubber is a fairly elastic material, and not much good for
>absorbing vibrations.
I've gotten a bit lost in the quotations of quotations here; but I
believe that you just restated the original poster's main point. That
tennis balls do not "absorb" energy particularly well, but that some
other kind of isolator -- on which the hammer also got dropped -- did
"absorb" the energy, or at least it seemed to in that the hammer did
not recoil from the drop, implying the energy imparted by it to the
given object went somewhere besides back to the hammer. By "absorb," I
do not mean to store, but to convert to another form or channel in
another direction.
>>Dick, My kitchen floor is not resilient. It is made of ceramic tile.
>>Hard as a rock. No give what-so-ever.
>
>So how is Dick to know what floor you have?
He couldn't; in which case, he should have asked rather the proceeding
under the assumption that the original poster had stated his case in
error.
>Dick, do you think you are explaining anything here? You inability to
>communicate with people other than engineers disqualifies you as
>"teacher".
I have to confess that this seems a bit harsh to me; but it does raise
a point. Specifically, that some of the more technically-minded
individuals in the newsgroup try to put down or intimidate the less
technically-inclined but equally creative thinkers with jargon. In
this case, I must confess that I have learned far more from chatting
with the occasional astrophysicist / professor about the physical laws
of nature than by having someone strongly imply -- in an open forum --
how stupid I am for thinking silver wire had audibly different
properties than copper.
thei...@usa.pipeline.com
'asc...@aol.com (Aschaub)' wrote:
>I've gotten a bit lost in the quotations of quotations here; but I
>believe that you just restated the original poster's main point.
Yes, you're right, I did. However, now that I have also lost myself
in the quotations, I believe Dick's point was that producing a highly
lossy material is trivially easy. For starters, try taking a large
glob of silicone-rubber vs a large glob of latex-based caulk (easily
available in most home basements ;) ) and dry them for a few hours at
least. Then drop a hammer on them. The latex caulk is extremely
absorbtive, particularly compared to the silicone, which is pretty
close to perfectly elastic. A tube of latex-based caulk is available
for about $2 at any local hardware store...not that it has any great
aesthetic qualities that lend it to be displayed with expensive
electronics. ;)
>>Dick, do you think you are explaining anything here? You inability to
>>communicate with people other than engineers disqualifies you as
>>"teacher".
I believe you are missing a ">" from your quotation, since this would
imply that I said the above, which I didn't. I understand the quotes
are a bit messed up overall, but please try to be careful! :)
>I have to confess that this seems a bit harsh to me; but it does raise
>a point. Specifically, that some of the more technically-minded
>individuals in the newsgroup try to put down or intimidate the less
>technically-inclined but equally creative thinkers with jargon.
I agree overall, but in many cases the only way to discuss a
technically-based issue is to use highly technical terms, or jargon as
you say. I don't think it is necessarily an intentional put-down or
intended as intimidation, although I haven't read every single post to
be able to give a second opinion. In many cases, I use a great deal
of what you would consider jargon simply because that is what I am
comfortable with, and what I use on a daily basis. In particular, the
way Dick stated his example should have been easy to understand for
anyone who has ever read a copy of Stereophile or ever discussed
crossover networks. In all seriousness, how would you describe a
mechanical 2nd order lowpass filter except by those words?
Ben Cannon
thei...@usa.pipeline.com () wrote:
>'Scott Weinmann <sco...@interramp.com>' wrote:
>>Dick, if you are the teacher, my kids are in some serious trouble! If
>>a tennis ball doesn't "RECEIVE, STORE-MOMENTARILY, and then RELEASE
>>ENERGY", then what the hell is it doing when it is struck? The
>>kinetic energy received by the ball when it is struck by the raquet is
>>converted into stored kinetic energy, which is then released, (along
>>with some heat through friction losses, of course, or a "super-ball"
>>would bounce forever.)
>
>I am sure that Dick will reply in kind, but must comment that the
>above explanation has a few glaring errors. The ball has a certain
>amount of kinetic and potential energy while in flight, then when
>struck with the racket, essentially converts kinetic to potential
>energy through compression of the rubber and air as well as the racket
>strings, and then back into kinetic energy upon expansion and reaction
>of the strings *minus* the heat through friction losses. The motion
>of the ball is governed by the laws of momentum, the racket being the
>much heavier item, moving much faster, thus the ball is now moving in
>the opposite direction.
I would say that's storing energy momentairly, then releasing it...
It is stored as compresion of the ball (of which the air is an
integral part) which is also "potential energy." Sure, the ball had
the energy all the time, but if Scott was talking exclusivly of
potential energy, he's dead on.
>Yes, but a hammer also bounces when you drop it on a slab of concrete.
Accually, a hammer bounces the best if you hit it against another
hammer :)
Stainless steel gives a near 100% rebound :) much better than a tenis
ball :)
--
Ben Cannon. art...@a.crl.com
"If you think it more, you will know it." -Joly
HTTP://168.75.121.2/ben.htm Between 3:00 and 9:00 Everyday.
Now with a high speed 28.8 connection and a new site adress!!
Aschaub
thei...@usa.pipeline.com writes:
>'asc...@aol.com (Aschaub)' wrote:
>
>>>Dick, do you think you are explaining anything here? You inability to
>>>communicate with people other than engineers disqualifies you as
>>>"teacher".
>
>I believe you are missing a ">" from your quotation, since this would
>imply that I said the above, which I didn't. I understand the quotes
>are a bit messed up overall, but please try to be careful! :)
Yes, you're right; my apologies. The preceding quote with ">>>" in
front of it should now have ">>>>" in front of it if had I added the
correct level of indirection originally.
>... comfortable with, and what I use on a daily basis. In
>particular, the way Dick stated his example should have been easy to
>understand for anyone who has ever read a copy of Stereophile or ever
>discussed crossover networks. In all seriousness, how would you
>describe a mechanical 2nd order lowpass filter except by those words?
Through analogy, precisely what most teachers of a new concept to a
given individual use. As an example, I could explain the process of
exposing and developing film to my girlfriend by using the analogy of
a sponge that soaks up light but doesn't actually change color until
you soak it in another chemical; this allows for the notion of a
minimum number of photons striking the silver granule to get any image
at all (pre-wetting the sponge with light) and the idea of a gradual
upper limit to the exposure range of the film (the sponge becoming
saturated with light and losing progressively more absorbtive
capability) without ever using the term, "latent image."
Ben Cannon
Scott Weinmann <sco...@interramp.com> wrote:
[ quoted text deleted -- jwd ]
> Dick, do you think you are explaining anything here? You inability
> to communicate with people other than engineers disqualifies you as
> "teacher". Teachers need to be able to describe new concepts
> without confusing the audience or assuming that they know more than
> they do. A "2nd order mechanical low-pass filter whose cutoff
> frequency is essentially that of the resonant frequency. As the
> external stimulus frequency increases above that resonance, the
> isolation provided by that filter increases as the square of the
> frequency". What the [place of Enturnment] are you talking about?
Oh, oh!! He's trying to explain why your car bounces UP! when you hit
a speedbump going 5MPH, and why you can't feel it at all hitting at 90
(not that I'd know.. <g>)
Incidentally, sience the "cutoff frequency" is where the suspension of
the car STARTS to absorb some of the bump, it's already resonating
like a Bose midrange if you go over fifty thousand speedbumps spaced
about a foot apart at the same speed... you follow?
So we've either got to make the resonant frequency really low, or stay
away form it alltogether.
A last note: does anyone accually belive these resonance things matter
in things except CD players (where word-clock jitter may be induced)??
Scott Weinmann
[moderator comment: many lines of quoted text were cut, this
should not obscure the meaning of this reply since this really
is a simple, high-school-physics question. -- rgd ]
thei...@usa.pipeline.com wrote:
> 'Scott Weinmann <sco...@interramp.com>' wrote:
[ excess quoted text deleted -- rgd ]
I wasn't talking about a moving tennis ball. I wa talking about a
stationary tennis ball that is about to get struck. The term that you
use, potential energy, is one that I have long since forgotten, but
now I recall.. Basically, I am absolutely correct. Is hould have
used the term potential energy instead of "stored kinetic energy".
> absorbing vibrations. However, have you ever tried to play with a
> tennis ball that has had a pinhole in it? Have you ever heard of a
> "dead" ball? Dick is quite right.
I have played paddletennis in California which is played with a tennis
ball that has a pin-hole in it. Again, the original post was about
"do tennis balls cut in half make good poor-mans feet for components".
[ quoted text deleted -- rgd ]
> So how is Dick to know what floor you have? I just dropped a 3lb
Dick ASSUMED my floor was resilient. Remember also that it was Dick
that said, "Let the teacher teach" and began the inflamed discussion.
Where can I buy scraps of your rug?
> Yes, but Dick gave you a good example of a much better system than the
> pure mechanical resistance that you have been describing. And your
Dick's "much better system" as you describe it is not available from
Audio Advisor or my local store for $35. If Dick can build me a
better "system" and sell me three feet for $35, I post my credit card
number right here in the newsgroup!
> square of the frequency." Sure, it would have been simpler to say
> it's a mechanical analogy to a 2nd order woofer crossover, but you
> seemed to have a fairly good grasp of technical terminology before, so
> a bit more detailed description was not out of order.
[ quoted text deleted -- rgd ]
Todd, you and Dick suffer from the same affliction. You know how you
aren't allowed to use the actual word to describe the word in play
when playing the old gameshow PassWord? If Dick wants to be
considered the "teacher" he'll need to be able to describe his
argument in terms that non-engineering types can understand. If he
can't, he should leave well enough alone. He was the one that boldly
annointed himself "teacher". I was just trying to explain in laymen's
terms why tennis balls wouldn't be such a great dissipator.
There is a commonality here amongst the engineers that frequent this
group (some further out to the right than others..). Everyone seems
to discuss "systems" and the like, when guys like me are discussing
products. I have at my disposal exactly what I see in magazines and
catalogs from Audio Outlet, Audio Advisor and others...Describing the
"perfect system" does me no good unless it is being built and sold, or
you intend to build and sell me one, for the same amount of money.
So, does anyone have a $35 set of three "things" (they can be a sytem
if you like) that will do a better job of dissipating the vibrations
that are generated from transformer hum and CD transport aberations
that I can place under my preamp, CD transport and amplifier?
I thought not.
And to the originators of this thread, tennis balls and raquet balls
are NOT the solution.
Bob Myers
Scott Weinmann (sco...@interramp.com) wrote:
> Dick, Dick, Dick. You and Bob at HP must spend a lot of time at "the
> bench" together. Don't you get it, yet? I am a consumer. I am not
> looking to "build a system", but rather to "buy" (for $35) something
> that will tame the vibrations being manifested from within my
> components..
I suppose that I must be the "Bob at HP", and so would just like to
state for the record that Dick and I have never played tennis
together.
What that has to do with audio is about as much as dropping hammers
onto the floor does.....
> Had you asked that question, instead of assuming (you know what
> happens when you assume... ;-))you would have discovered that I am
> not looking to ISOLATE my components. I was looking for an "Energy
> Sink", for lack of a better term, to dissipate microvibrations
> emanating from WITHIN my components (stuff like transformer hum, CD
> transport aberrations, etc.)
Well, I'm not 0.1 the speaker expert that Dick is, but if I may, a
question: have you tried Silly Putty?
Bob Myers KC0EW Hewlett-Packard Co. |Opinions expressed here are not
Workstations Systems Div.|those of my employer or any other
my...@fc.hp.com Fort Collins, Colorado |sentient life-form on this planet.
jj, curmudgoen and all-around grouch
In article <4pc5ev$3...@eyrie.graphics.cornell.edu> Scott Weinmann
<sco...@interramp.com> writes:
>> compressibility of air. The rubber the ball is made out of is a
>Had you asked that question, instead of assuming (you know what
>happens when you assume... ;-))you would have discovered that I am
>not looking to ISOLATE my components. I was looking for an "Energy
>Sink", for lack of a better term, to dissipate microvibrations
>emanating from WITHIN my components (stuff like transformer hum, CD
>transport aberrations, etc.)
Hmmm. Microvibrations? Ok. Why do you want to absorb them. How do
you suppose that absorbing them is better than, say reflecting them?
What is the POINT here, what are the "microvibrations" doing that you
need to ABSORB them?
>Dick, do you think you are explaining anything here? You inability to
>communicate with people other than engineers disqualifies you as
>"teacher".
Ok. I see. The problem is that Dick is so far ahead of you that he's
probably answered the question you just asked.
Oh, and yes, it's a relevant question, indeed. f = ma, there's no
such thing as a free lunch, OR a reactionless "absorb".
--
Copyright akalice!jj 1996, all rights reserved, except transmission by USENET
and like facilities granted. This notice must be included. Any use by a
provider charging in any way for the IP represented in and by this article
and any inclusion in print or other media are specifically prohibited.
Bruce Seiler
In article <4p5op6$p...@agate.berkeley.edu>, m...@ix.netcom.com (marivic canlas salamat) writes:
|> I would like to relate alittle story
...
|> To sum the sound I got from the system-on-the-mattress,
|> it was relaxed, detailed, and very musical, like the noise floor
|> becoming non-existent. Has anybody tried this, or accidentally
|> stumbled on it? RS
|> |
A few months ago, the Stereophile letters section had a letter from a
woman who related her husband found their system sounded better when
supported by those little cushy donuts sold for hemoid sufferers to
sit on. I have a few left over from my wife's pregnancy and I hope to
give them a try. By the way, the wife wrote because the husband
thought it would sound silly!
Bruce Seiler
sei...@compass-da.com
Eric Soroos
In article <4pjth2$e...@eyrie.graphics.cornell.edu>, my...@hpfcla.fc.hp.com
(Bob Myers) wrote:
>
>> Had you asked that question, instead of assuming (you know what
>> happens when you assume... ;-))you would have discovered that I am
>> not looking to ISOLATE my components. I was looking for an "Energy
>> Sink", for lack of a better term, to dissipate microvibrations
>> emanating from WITHIN my components (stuff like transformer hum, CD
>> transport aberrations, etc.)
>
>Well, I'm not 0.1 the speaker expert that Dick is, but if I may, a
>question: have you tried Silly Putty?
Assuming that what you want is something that deforms to "absorb"
vibration like what you saw at at the demo try:
A bag of sand.
A bike tube filled with the tire goo that makes you think you won't
get a flat.
Styrofoam Packing peanuts in a bag
That foam that people sleep on when camping.
The foam from the boxes that Apple uses to ship powerbooks.
As an aside, that last one seems to improve the transient performance
of my cd player. (Transient performance meaning that it doesn't skip
when I'm jumping around dancing to the tunes)
As for damping/isolating to protect from transformer hum, I'll defer
to jj and Mr Pierce, for they have more patience for this than I have.
eric
--
sor...@u.washington.edu
http://www.ce.washington.edu/~soroos
jj, curmudgeon and all-around grouch
Somebody:
> I have to confess that this seems a bit harsh to me; but it does
> raise a point. Specifically, that some of the more
> technically-minded individuals in the newsgroup try to put down or
> intimidate the less technically-inclined but equally creative
> thinkers with jargon.
This is called "biting the hand that feeds you.
Dick. This guy thinks we can all discuss intricate technical details
without using intricate technical terms, even if the results are
highly anti-intuitive, and require jargon to explain.
I submit that when people make technical claims, or wish to argue bout
technical claims, then they are obligated to learn the language. If
they won't learn the language, then they don't want to be serious.
What's more provoking is that Dick provided a conceptual definition
with his terms, but you don't want that. You'd rather argue that
ignorance has the right to dispute experience.
Well, it does. And ignorance usually (but not always, just look at
our congress and white house) gets what it has coming.
Finlay Evans
I don't want to sift through all the previous relevant messages to
quote exactly what people said but I think I can help in this area of
Hi-Fi.
First the question of 'resilience', 'give', 'hardness' etc. Every
solid has a property called Modulous of Elasticity, 'E'. This
determines how much force or energy is required to deform it a certain
amount (in layman's terms). Every object deforms a certain amount
when a force is acted on it, no matter how small the force it is not
perfectly rigid. A bar made of steel is thus STIFFER than a bar made
of rubber. 'Resilience' and 'give' are descriptive terms of very
stiff and not very stiff. 'Hardness' is something completely
different but in the context it was used I beleive it was meant as
being very stiff.
Dissipation of energy occurs whenever deformation of an object occurs.
Period. The amount of enery dissipated for a given deformation
depends on the material.
Thus a squash ball bouncing on a stone floor will deform more than a
steel ball (of the same weight, to keep the kinetic energy the same
for both cases), and due to the larger deformation, and the fact that
rubber dissipates more energy than steel when deformed, the squash
ball dissipates much more energy than the steel ball. However both
balls AND the stone floor are deforming during this hypothetical
experiment. The reason a tennis ball with a hole in it bounces less
than a sealed one is the air inside is not acting as a spring since it
is not getting compressed (it leaks out), thus reducing the
'stiffness' of the ball. The 'holed' ball then deforms more
dissipating more energy.
Ok. Now the question of Isolation, Absorption and Dissipation.
If you want to prevent vibrations getting to your CD-player from the
floor then the ONLY way is by ISOLATION. There is no point in trying
to dissipate energy into anything resting under or on your CD-player,
all you will do is transmit forces to the player. To isolate an
object you connect it to ground (or whatever you want to isolate it
from) with a spring. (any object that deforms elastically) The
stiffness of this spring in relation to the mass of the object being
isolated (the CD-player) determines the highest frequency which is
isolated, just like an LC filter as has been pointed out. For a given
mass of player, if you quarter the stiffness of the supports, you
halve the cutoff frequency of the isolation. So for really good
isolation you want really soft supports. The problem with this is
that you need to compress a soft spring a long way to get enough
static force to support a CD-player. This is difficult to do in a
small space. Many things, including sponge pads, tennis balls etc,
get stiffer as they compress more and more, until by the time they are
supporting a CD-player they are too stiff to act as isolators. Try a
bicycle inner tube, with hardly any air in it (as reccommended here by
a previous poster). This works fairly well but if you leave a loop of
it free behind the player then it becomes a softer spring and works
better. Lower frequency vibrations will always get to the player, so
you need to judge where an acceptable cutoff is. You can never
isolate to 0.0 Hz, although 1 or 2 Hz is feasible with ingenuity.
This will isolate the player from ground vibrations, but not from
airborne vibrations. The only way to stop these forces getting to
your player is to put it in a vacuum. Not very feasible. The next
best thing is to increase the mass of the player CASING. This reduces
the amplitude of vibration of the casing, reducing the airborne
vibrations the casing induces in the internal air cavity of the
player. Sand in a bag is ideal since not only does this increase the
mass, but it also means that the particles will vibrate in different
directions due to the loose nature of the particles, thus absorbing
some of the vibration. Placing the player on a bag of sand to absorb
ground vibrations will not work very well since sand acts more as a
solid as it is compressed. (although it will reduce base panel
vibrations created by airborne vibrations so ideally could be used
with isolators)
This post is longer than anticipated but I hope it will clear up
contradiction and confusion within the topic.
Finlay Evans.
Nonlinear Dynamics Group
Department of Engineering
University of Aberdeen Tel: +1224 272524
Old Aberdeen Fax: +1224 272497
Greg Wormald
Tennis balls don't work. Try cutting 3 inch diameter circles out of a
wool 'hard twist' carpet, glueing a thin rigid layer (plywood works OK
if you can't get any of the rigid foams) onto the back and using wool
side down under the component's feet. Enjoy.
--
Greg
gwor...@dove.mtx.net.au
jj, curmugeon and all-around grouch
In article <4pjq6e$b...@tolstoy.lerc.nasa.gov> Scott Weinmann
<sco...@interramp.com> writes:
> So, does anyone have a $35 set of three "things" (they can be a sytem
> if you like) that will do a better job of dissipating the vibrations
> that are generated from transformer hum and CD transport aberations
> that I can place under my preamp, CD transport and amplifier?
Well, since f = ma despite all this, let me ask a simple question:
Do these absorbers weigh a lot more than the turntable and the
shelf the turntable is on?
Do they slowly but surely get shorter and shorter as time goes on?
These two questions really do sum up the problem, and the physics
involved.
[ Sigh. Poor JJ. Still hasn't figure out that physics has NOTHING
to do with AUDIO. Tsk, tsk, tsk ... :-) jwd ]
thei...@usa.pipeline.com
'Scott Weinmann <sco...@interramp.com>' wrote:
>I wasn't talking about a moving tennis ball. I wa talking about a
>stationary tennis ball that is about to get struck. The term that you
>use, potential energy, is one that I have long since forgotten, but
>now I recall.. Basically, I am absolutely correct. Is hould have
>used the term potential energy instead of "stored kinetic energy".
Actually, my objection to your comments was that it might appear to
the extremely non-scientific that you were *adding* losses to the
energy of the system rather than saying subtracted. It all depends on
how you define losses, and it may well be that you and most people
consider losses to be "negative" by default and thus it's simply
semantics. At any rate, the losses in friction are very significant,
on the order of 25%. A simple experiment with dropping anything but a
brand new tennis ball will show you the percentage of energy remaining
after one bounce, neglecting air drag at such low velocities. So
perhaps the rubber and construction of a tennis ball is a fairly
decent absorber after all.
>Again, the original post was about "do tennis balls cut in half make good
>poor-mans feet for components".
And judging from the simple experiment, the answer, so long as the
tennis ball is roughly half-spherical, and not flattened by the weight
of the component, is yes. For a free tweak, it's a heck of a deal!
>Dick ASSUMED my floor was resilient. Remember also that it was Dick
>that said, "Let the teacher teach" and began the inflamed discussion.
>Where can I buy scraps of your rug?
Er...how about $300 per square foot? Any takers? Seriously, though,
I think an isolator of rug would be a really interesting tweak, having
an aesthetic quality as well as functional one. Considering that
audiophiles generally prefer the sound of wool damping inside
loudspeakers, perhaps an authentic, hand-woven wool rug piece would
have an equivalent effect on components? A new marketing idea!!! I
think I'll patent it! ;)
>> Yes, but Dick gave you a good example of a much better system than the
>> pure mechanical resistance that you have been describing. And your
>Dick's "much better system" as you describe it is not available from
>Audio Advisor or my local store for $35. If Dick can build me a
>better "system" and sell me three feet for $35, I post my credit card
>number right here in the newsgroup!
A useful point to bring up at this time is that a decent number of
audio manufacturers, sellers and the like skim this n.grp. all the
time, and some may actually take note of a few things mentioned here.
And if Dick doesn't have the time to actually build these things,
perhaps one of the manufacturers will?
>Todd, you and Dick suffer from the same affliction. You know how you
>aren't allowed to use the actual word to describe the word in play
>when playing the old gameshow PassWord?
Never watched it. Have no idea!
>I was just trying to explain in laymen's
>terms why tennis balls wouldn't be such a great dissipator.
And I just pointed out above a simple way of showing the dissipative
ability of a tennis ball, simply by measuring the relative height of
bounces and thus the potential energy loss of the system at every
bounce. In this case, the best method might well be to puncture the
ball to release the air pressure (it is closer to the final result of
a ball cut in half) and measure the loss. I suspect it will be much
greater than the first case, although I have only measured the first
case (perhaps as much as 50%). A free tweak that's half as effective
as a $110 tweak is a good one to me!
>Everyone seems to discuss "systems" and the like, when guys like me
>are discussing products. I have at my disposal exactly what I see in
>magazines and catalogs from Audio Outlet, Audio Advisor and
>others...Describing the "perfect system" does me no good unless it is
>being built and sold, or you intend to build and sell me one, for the
>same amount of money.
Right, but two important comments. One, a description of the "perfect
system" may allow you to cut through the technobabble of an
advertiser's spiel to the real meat of how their system works, and see
whether it really is better from a technical standpoint at whatever it
does than the competition. That way you might make an informed
opinion as to which to buy or which to audition. In some cases, you
might be able to eliminate one or more products from a so-called
"long-list" of possible candidates without actually ever seeing them.
The second comment would be that as above, that some manufacturer who
may well be non-technical (as I suspect the people who "develop" the
isolators are) might actually read this and produce the product.
While this may not necessarily help you in the present, it very well
might in the near future.
>So, does anyone have a $35 set of three "things" (they can be a sytem
>if you like) that will do a better job of dissipating the vibrations
>that are generated from transformer hum and CD transport aberations
>that I can place under my preamp, CD transport and amplifier?
>
>I thought not.
Not me, I have too many things to do that I prefer, rather than
spending my time with items that I consider to be marginally useful if
not useless. But I can suggest a better poorman's solution (as I
*did* previously), that of using a chunk of a soft latex-based caulk
such as Red Devil's "Speed Demon" or DAP's ALEX Plus acrylic latex
caulk plus silicone. I suggest the DAP because it is a bit more
resilient, and depending on the weight of the item (like an amp) you
might need a bit more strength than latex can support. The best
method for construction (to me) would be to take a sharp knife and
slice the entire tube from top to bottom on one side, pry it open
slightly (about 1/16") and let the tube dry completely (may take a day
or two). Then cut it into discs of your preference in height (.5"
should be enough). I would suggest finding a fairly dense closed-cell
foam, perhaps a 3M nitrile adhesive-backed tape or it's like to
conceal what your new isolators are made of, and to add another
section of isolation. Considering that most components are somewhat
frequency-dependent in isolation, you can't be certain that any one
component isn't a virtual brick to certain frequencies without
actually measuring it, so in this case, two different components can't
hurt.
So is that enough of a reply? I said it before, but you ignored it.
So here it is again.
>tennis balls and raquet balls are NOT the solution.
Racquetballs, no. Tennis balls, perhaps. I really don't feel like
building a test facility to run into the AP to find out, so I can only
offer suggestions. But there's nothing quite like a tweak that you
build yourself!
Eleanor Ide
>woman who related her husband found their system sounded better when
>supported by those little cushy donuts sold for hemoid sufferers to
>sit on. I have a few left over from my wife's pregnancy and I hope to
I really don't get this vibration damping of CD players thing. I can
PICK UP my CD player and vibrate, reorient, or otherwise play around
with it and it sounds exactly the way it does sitting on the shelf,
unless I get overzealous and make it skip.
I've yet to try applying a vibrator (the jelly kind should have good
vibration conduction to the chassis) to the thing but the more I hear
about Seismic Sinks and tennis balls making a difference, the more I
think I should, just to disabuse myself of the notion that these
things have any chance of being worth the money or trouble.
My turntable, on the other hand, sure could have used something like
that in the old house, when I had it on the second floor. Now I'm
living in the bottom of a townhouse, with vinyl flooring on a concrete
slab, and I can stomp around all I want without bothering the
turntable. Hit the entertainment center the thing is on, though, and
you'll hear it. <sigh> I'm glad I've taped all my records.
Rob Lewis
Ben Cannon wrote:
[Text deleted]
> A last note: does anyone accually belive these resonance things matter
> in things except CD players (where word-clock jitter may be induced)??
>
> --
> Ben Cannon. art...@a.crl.com
> "If you think it more, you will know it." -Joly
> HTTP://168.75.121.2/ben.htm Between 3:00 and 9:00 Everyday.
> Now with a high speed 28.8 connection and a new site adress!!
Yes. There are a number of things going on with audio equipment that
defy common sense. First, there is microphonics; Some parts in a
system have a tendency to convert sound into an electric signal. As
far as I know, this is only a problem with tubed gear, but who knows?
Secondly, there is mechanical vibration, either from the rack, or from
within a component itself. The problem here is that there are
magnetic fields everywhere in your system caused by the flow of
current through wires and parts. Periodic motion of wires and parts
in this field causes changes in current flow, polluting the audio
signal.
You also have acoustic vibration from the loudspeakers (the point of
this mad pursuit). Each component (and the rack that they sit on)
will have its own resonant modes and frequencies that excite those
modes. At resonant frequencies, (particularly at high spl) you will
get mechanical vibration interacting with the present and always
changing magnetic fields again polluting the signal.
In addition, there is RF all over the place, and unless you have a
quality line conditioner, your power will have noise. No voltage
regulator is perfect, so the better the power is going into one, the
better it is coming out.
Oh yeah, and there's the room. What if the room has a strong resonant
mode at the same frequency as one of your component chassis? That
thing'll really be thumpin'! All of these things interact in a
complex non-linear fashion.
It is my belief that a lot of the cost of *really* good high-end gear
goes into providing effective isolation from all of this. No system
can ever be totally isolated, but the better gear sees much less
improvement in these areas from tweaks/treatments; although the higher
the resolution, the more audible small improvements become. After
all, the ultimate goal is to convert changes in sound pressure at a
live event to electrical signal, and back again without changing it at
all. Anything that does change it, should be viewed as a problem.
As for whether tennis balls are effective as isolators of mechanical
vibration, I cannot say.
---
Rob Lewis rle...@opal.tufts.edu
New England Medical Center
Neuroimaging Research Laboratory ---> Audio ergo sum <---
Alistair MacKinnon
MMMM, I was inadvertently in Sportsmart today, and they were offering
weight absorbent rubber(?) carpet for weight traing. It supposedly
absorbs the power of a dropped weight and helps keep your floor in
good condition. The sticker also claimed that the product absorbed
"sound"? Price @30 for two large slabs. just an FYI
rd...@shell.portal.com
In article <4pjq6e$b...@tolstoy.lerc.nasa.gov>,
Scott Weinmann <sco...@interramp.com> wrote:
>
>So, does anyone have a $35 set of three "things" (they can be a sytem
>if you like) that will do a better job of dissipating the vibrations
>that are generated from transformer hum and CD transport aberations
>that I can place under my preamp, CD transport and amplifier?
>
Something that may be being overlooked is what the desired result is.
Do you want to dissipate, or isolate? It seems to me that any
externally applied method would mostly be good at isolation, cutting
down on vibrations within a component generated by that component
would require internal modifications to be most effective. As other
have pointed out, isolation requires forming what is basically a low
pass filter vibration wise, which does not necessarily require
dissipation or absorption.
Any real comparison of different methods would require real testing,
which no one has a vested interest in for low cost or pseudo free
solutions.
If I may offer my own low cost solution, try ensolite, closed cell
foam available as sleeping pads at sporting goods stores, with perhaps
small squares of hardboard to spread the weight distribution out from
the feet over a few square inches. And a 30 inch by 60 inch by 1/2
inch pad runs about ten dollars. I isolated my whole stereo system
from rather shaky floor boards once with about 3 inches thickness cut
from these. Nicely damped, and compressed down to about half the
thickness from the weight.
--
Richard Dell
Rndmtn
I know what ensolite looks like but I am aware there are two types.
The blue lightweight type and the more heavy version of it. Which one
would work and should you use a particular piece of hardwood to
isolate stuff.
I was thinking about getting a Seismic Sink for the AR ES-1 I just got
but I want to spend the money on more worthy nonimportant items like
cartridges, new belts and maybe a new tonearm. If this can do it for
a fraction of the cost, I am open to it.
thanx
d maruyama
Richard M. Anderson
Home Depot carries a door-knob wall impact preventer that makes an
excellent isolator. It comes in a pack of two for about $4.00 It's a
half-sphere (to fit a concave door knob) is made of a rubbery plastic
and has an adhesive backing. It's diameter is about two inches so it
can be stuck on the bottom legs of various pieces of equipment. It
comes in white, grey, and an cream colour. I've put these on most of
my equipment and they work very well. sinc; Rich
Chatr Suchinda
Here is the result from tennis ball experiment.
I tried the tennis ball isolator with my Linn Karik & Numerik CD
Player. Each three Penn tennis ball is sitting on Tropicana orange
juice cap just for stability purpose. The juice caps are put on the
medium thick carpet. Both Karik and Numerik are sitting on all three
tenis balls.
First I listened to the Bach's Brandenburg Concertos #3-5 (Pillips
Classic 400 077-2 CD). I notice a lots of improvement from the music
reproduced by Linn CD player without the tennis ball isolator. I can
hear more individual expression on each instrument. As before Linn CD
player has very outstanding quality in this respect of seperating all
instruments in the sound space. With Linn CD player on the tennis
balls, all instruments sound more individual by comparision. With
tennis ball isolation, it seems that the spaces between instruments
are widen. However, there is a negative effect on the total sonic
quality. I noticed the fundamental resonance, This resonance occur
about the same frequency of the tennis ball when it was hit by the
tennis racket (bonk bonk sounds). My idea is if I can lower the
fundamental freqency of the system (that is the tennis balls, Karik,
and Numerik) well below the audio frequency it will be great. The
fundamental will not be hearable.
So I added more mass in the system. I put my textbooks on top of the
Karik one by one. I heard that the resonance of the system got lower
and lower. Until I put 5-6 textbooks on top of the Karik and the
fundamental frequency was around 90-100Hz. I should put more
textbooks but I used up all mine and the stack of textbooks was
getting too tall to be stable. I quite satisfied with the sonic
quality. I think the perfect isolation system can be acheived if I
buy the Big Rock and Small Rock isolator which Stereophile reveiwed.
They said this isolator system uses air blade and add mass on the CD
Player by the Small Rock. The system fundamental freqency is around 1
Hz which well below the audible frquency.
From the result of this experiment, I beleive that the tennis balls
act with the stack of textbooks as the isolator system. Mainly the
tennis balls provide stiffness (k) to the system while the textbooks
provide mass (m) to the system. The fundamental freqency can be
estimated by assuming the system as a single degree of freedom system.
Freq = Square root of (k/m)
By adding more mass, the fundamental freqency of the system is lower.
By increasing the stiffness (harder tennis balls), the system gets
higher frequency. Tennis balls also provide some dumping (c) to the
system. This can also be considered as the energy dissipator.
(Without the damping at all, the system will be osilate forever!).
s the conclusion, the tennis balls give both act as a part of isolator
and also give some energy dissipator as mechanism despcribe above.
--
Chatr Suchinda, Ph.D. Candidate
Georgia Institute of Technology, Atlanta Georgia, 30332
Internet: cs...@prism.gatech.edu