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muzician21 muzician21 is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

On this page

http://www.bornrich.org/entry/top-10...ve-turntables/

Look at number 5 - the description of the Continuum Caliburn includes
this phrase:

"The turntable employs a magnetically levitated magnesium platter,
which is suspended in a vacuum to guarantee there are no vibrations."

Suspending in a vacuum sounds like a contradiction in terms. A vacuum
tends to draw things in. At some point the turntable has to be riding
on some kind of bearing - i.e. something solid has to be contacting
something solid - which AFAIK provides a potential conduit for
vibration transmission. From a theoretical standpoint, how would you
"suspend" something like this in a vacuum in a way that guarantees no
vibration?

And of course a vacuum requires a seal, which sounds like something
with the potential to fail.
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Scott Dorsey Scott Dorsey is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

muzician21 wrote:
On this page

http://www.bornrich.org/entry/top-10...ve-turntables/

Look at number 5 - the description of the Continuum Caliburn includes
this phrase:

"The turntable employs a magnetically levitated magnesium platter,
which is suspended in a vacuum to guarantee there are no vibrations."

Suspending in a vacuum sounds like a contradiction in terms. A vacuum
tends to draw things in. At some point the turntable has to be riding
on some kind of bearing - i.e. something solid has to be contacting
something solid - which AFAIK provides a potential conduit for
vibration transmission. From a theoretical standpoint, how would you
"suspend" something like this in a vacuum in a way that guarantees no
vibration?


It is magnetically suspended. The vacuum will prevent air currents from
moving the plinth around. However, the vacuum will also change the damping
of the cartridge somewhat, and I am not sure what it will do to the
record/stylus interface.

And of course a vacuum requires a seal, which sounds like something
with the potential to fail.


Yes, of course. Machinery is like that.
rec.audio.opinion removed from the Newsgroups: line for the obvious reasons.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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William Sommerwerck William Sommerwerck is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

Suspending something in a vacuum does not, in and of itself "prevent
vibrations". Whoever wrote this promotional material has little practical
understanding of physics.


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George's Pro Sound Company George's Pro Sound Company is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?


"Scott Dorsey" wrote in message
...
muzician21 wrote:
On this page

http://www.bornrich.org/entry/top-10...ve-turntables/

Look at number 5 - the description of the Continuum Caliburn includes
this phrase:

"The turntable employs a magnetically levitated magnesium platter,
which is suspended in a vacuum to guarantee there are no vibrations."

Suspending in a vacuum sounds like a contradiction in terms. A vacuum
tends to draw things in. At some point the turntable has to be riding
on some kind of bearing - i.e. something solid has to be contacting
something solid - which AFAIK provides a potential conduit for
vibration transmission. From a theoretical standpoint, how would you
"suspend" something like this in a vacuum in a way that guarantees no
vibration?


It is magnetically suspended. The vacuum will prevent air currents from
moving the plinth around. However, the vacuum will also change the
damping
of the cartridge somewhat, and I am not sure what it will do to the
record/stylus interface.

And of course a vacuum requires a seal, which sounds like something
with the potential to fail.


Yes, of course. Machinery is like that.
rec.audio.opinion removed from the Newsgroups: line for the obvious
reasons.



but if the magnets vibrate would not the change in flux vector cause a
vibration in the suspended object
George


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Scott Dorsey Scott Dorsey is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

George's Pro Sound Company wrote:

but if the magnets vibrate would not the change in flux vector cause a
vibration in the suspended object


Yup! Magnetic suspension is hard to make work properly.... you need to have
a constant flux over a wide area so that if the base vibrates, the field
at the plinth magnets doesn't change much if at all. You can make it work
but it's hard to make it as effective as cheaper alternatives.

On the other hand, those cheaper alternatives ALSO require some careful
engineering and they don't always get it. I can think of a mastering house
in NYC that was having trouble with building vibration from the subway and
installed a fancy isolated platform whose suspension had a resonance around
0.5 Hz which would get excited into wild motion by the subway....
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."


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George's Pro Sound Company George's Pro Sound Company is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?


"Scott Dorsey" wrote in message
...
George's Pro Sound Company wrote:

but if the magnets vibrate would not the change in flux vector cause a
vibration in the suspended object


Yup! Magnetic suspension is hard to make work properly.... you need to
have
a constant flux over a wide area so that if the base vibrates, the field
at the plinth magnets doesn't change much if at all. You can make it
work
but it's hard to make it as effective as cheaper alternatives.

On the other hand, those cheaper alternatives ALSO require some careful
engineering and they don't always get it. I can think of a mastering
house
in NYC that was having trouble with building vibration from the subway and
installed a fancy isolated platform whose suspension had a resonance
around
0.5 Hz which would get excited into wild motion by the subway....
--scott
--

at one time I sold Camera that were mounted to electron scanning
microscopes
one I personal was involved with was the on in the botony building at
cornell university
the professors there told me that a bus driving 1/4 mile away cause so much
vibration to render the microscope useless
so the scope was mounted to a 12 foot by 12 foot 25 foot deep slab of
reinforced concrete
I sure there were more details about suspension and stuff but this is what
it takes to eliminate common vibrations from devices


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Michael R. Kesti[_3_] Michael R. Kesti[_3_] is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

William Sommerwerck wrote:

Suspending something in a vacuum does not, in and of itself "prevent
vibrations". Whoever wrote this promotional material has little practical
understanding of physics.


I worked for about a year for a company that makes chambers, valves, and
pumps for the high vacuum industry and was amazed at the misconceptions
of many within the company concerning high vacuum. The best was the
assembly technician who confused vacuum and gravity and believed that
astronauts floated around as they do because they were in the vacuum of
space!

--
================================================== ======================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mrkesti at hotmail dot com | - The Who, Bargain
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Arny Krueger Arny Krueger is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

"George's Pro Sound Company" wrote in
message m
"Scott Dorsey" wrote in message
...


It is magnetically suspended. The vacuum will prevent
air currents from moving the plinth around. However,
the vacuum will also change the damping
of the cartridge somewhat,


Negligible if relevant, but the picture tells a different story. I recollect
that Scott's browser does not show pictures as easily as the ones most of us
use.

and I am not sure what it
will do to the record/stylus interface.


If you look at the picture, the plinth, the platter, the tone arm, and the
cartridge are out in the air. The evacuated chamber must be below the plinth
where we can't easily see it.

http://www.bornrich.org/entry/top-10...ve-turntables/

Item 5 - the Continuum Caliburn.

but if the magnets vibrate would not the change in flux
vector cause a vibration in the suspended object


George, you are so right. Magnetic suspension creates a force that varies,
depending on the distance between the magnet and the suspended object. If
the magnet moves closer to the object, then the force on the object
increases. Sort of like a spring.

Magnetic suspension's big advantage is reduced friction that would oppose
the rotation of the platter. It is used to create so-called 'frictionless"
bearings.

As a suspension that would resist or absorb vibration, magnetism shapes up
as just another combination of mass, spring, and damper.


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UnsteadyKen[_3_] UnsteadyKen[_3_] is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

William Sommerwerck wrote...

Suspending something in a vacuum does not, in and of itself "prevent
vibrations". Whoever wrote this promotional material has little practical
understanding of physics.


It's the fault of whichever eedjit wrote the article for bornrich. He
appears to have confused the bearing design with the vacuum platter
clamping system.

Continuum themselves say...

"Other features include the use of a ball/thrust pad configuration for
vertical motion, and bronze alloy for the axial motion.

The bronze alloy contains higher than normal tin compounds, which fill
any micro asperities in the shaft over time to create an ultra silent
bearing.

We chose not to use magnetic vertical bearings as the VTA is constantly
changing due to the rotational effects of the platter, which results in
a loss of depth and soundstage."


The whole things rubbish, VPI will no doubt be surprised to learn that
they are now a subdivision of the Teac corp and that their HRX table
features 24 extremely, 300rpm AC synchronous motors, Or perhaps not.

I'm off to read the in depth reviews at
http://www.bornrich.org/entry/top-10...everyone-cant-
afford/

--
Ken
http://www.members.lycos.co.uk/buddyduck/
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Scott Dorsey Scott Dorsey is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

George's Pro Sound Company wrote:
at one time I sold Camera that were mounted to electron scanning
microscopes
one I personal was involved with was the on in the botony building at
cornell university
the professors there told me that a bus driving 1/4 mile away cause so much
vibration to render the microscope useless
so the scope was mounted to a 12 foot by 12 foot 25 foot deep slab of
reinforced concrete


This is normal. Mass is your friend. I have a small slab poured here
which is isolated from the rest of the building foundation and has the
lathe and turntable mounted on it. It's only a fraction of that size
but it seems to do pretty well.

I sure there were more details about suspension and stuff but this is what
it takes to eliminate common vibrations from devices


The lower the frequency, the more mass it takes.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."


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Paul Stamler[_2_] Paul Stamler[_2_] is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

"Scott Dorsey" wrote in message
...
muzician21 wrote:


It is magnetically suspended. The vacuum will prevent air currents from
moving the plinth around. However, the vacuum will also change the
damping
of the cartridge somewhat, and I am not sure what it will do to the
record/stylus interface.


Would it also accelerate the leaching of plasticizers from the vinyl?

Peace,
Paul


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Scott Dorsey Scott Dorsey is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

Paul Stamler wrote:
"Scott Dorsey" wrote in message
muzician21 wrote:


It is magnetically suspended. The vacuum will prevent air currents from
moving the plinth around. However, the vacuum will also change the
damping
of the cartridge somewhat, and I am not sure what it will do to the
record/stylus interface.


Would it also accelerate the leaching of plasticizers from the vinyl?


Maybe, but you're putting the thing in there for only an hour or so at
a time. Be a fun thing to measure, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Ben Bradley[_2_] Ben Bradley[_2_] is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

(RAO deleted)

In rec.audio.opinion,rec.audio.pro, On Wed, 24 Dec 2008 17:36:45
-0000, UnsteadyKen wrote:

William Sommerwerck wrote...

Suspending something in a vacuum does not, in and of itself "prevent
vibrations". Whoever wrote this promotional material has little practical
understanding of physics.


It's the fault of whichever eedjit wrote the article for bornrich. He
appears to have confused the bearing design with the vacuum platter
clamping system.


Okay, NOW the idea of a vacuum related to a turntable makes sense.
I'd worry about air seeping through the vacuum system and making
noise, but for what they're charging I "presume" they have that worked
out.

Now if I only knew what a "Resonance Annihilator" and
"liquid-nitrogen-rectified belt" are. Geez, you'd think someone would
make a super turntable that has ALL these features.



Continuum themselves say...

"Other features include the use of a ball/thrust pad configuration for
vertical motion, and bronze alloy for the axial motion.

The bronze alloy contains higher than normal tin compounds, which fill
any micro asperities in the shaft over time to create an ultra silent
bearing.

We chose not to use magnetic vertical bearings as the VTA is constantly
changing due to the rotational effects of the platter, which results in
a loss of depth and soundstage."


The whole things rubbish, VPI will no doubt be surprised to learn that
they are now a subdivision of the Teac corp and that their HRX table
features 24 extremely, 300rpm AC synchronous motors, Or perhaps not.

I'm off to read the in depth reviews at
http://www.bornrich.org/entry/top-10...everyone-cant-
afford/


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Misifus[_2_] Misifus[_2_] is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

Scott Dorsey wrote:
George's Pro Sound Company wrote:
at one time I sold Camera that were mounted to electron scanning
microscopes
one I personal was involved with was the on in the botony building at
cornell university
the professors there told me that a bus driving 1/4 mile away cause so much
vibration to render the microscope useless
so the scope was mounted to a 12 foot by 12 foot 25 foot deep slab of
reinforced concrete


This is normal. Mass is your friend. I have a small slab poured here
which is isolated from the rest of the building foundation and has the
lathe and turntable mounted on it. It's only a fraction of that size
but it seems to do pretty well.

I sure there were more details about suspension and stuff but this is what
it takes to eliminate common vibrations from devices


The lower the frequency, the more mass it takes.
--scott



It's not just the mass, it's also isolating that mass from other
vibrations. There was a time when such slabs were floated in a pool of
mercury, which effectively decoupled it from the ground. However, since
the demonization of Mercury, I doubt it's still used anywhere.

-Raf

--
Misifus-
Rafael Seibert

Photos: http://www.flickr.com/photos/rafiii
home: http://www.rafandsioux.com
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Richard Crowley Richard Crowley is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

"Misifus" wrote ...
It's not just the mass, it's also isolating that mass from other
vibrations. There was a time when such slabs were floated in a pool of
mercury, which effectively decoupled it from the ground. However, since
the demonization of Mercury, I doubt it's still used anywhere.


When we manually probe the interior circuitry of an integrated
circuit (under a microscope), we use a table with a massive steel
table-top suspended on three air-bags (with servo valves to keep
it level).

Similar measures are used on the photolithography equipment which
exposes the dozens of patterns that make up a modern integrated
circuit chip. Between the suspension and the active servo-controlled
positioning (measured by laser interferometry), they can print dice
without any errors even through an earthquake.




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Chris Hornbeck Chris Hornbeck is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

On Sun, 28 Dec 2008 20:12:19 -0800, "Richard Crowley"
wrote:

When we manually probe the interior circuitry of an integrated
circuit (under a microscope), we use a table with a massive steel
table-top suspended on three air-bags (with servo valves to keep
it level).

Similar measures are used on the photolithography equipment which
exposes the dozens of patterns that make up a modern integrated
circuit chip. Between the suspension and the active servo-controlled
positioning (measured by laser interferometry), they can print dice
without any errors even through an earthquake.


I have an Intel "wafer" from back in the 486 era, when Ginny
was still teaching and Intel provided it along with some other
elementary school materials. The dies, if separated, would be
about 0.65 cm x 0.75cm and the bisquit itself is a little less
than 15cm circumference. No clue what it is.... hint, hint...

*Nobody*, and I mean *nobody*, who's seen this under a (phono
stylus, stereo) microscope hasn't been blown away. For technically
hip folks it approaches the religious.

Not at all kidding. Worlds within worlds.

Much thanks, as always,
Chris Hornbeck
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Richard Crowley Richard Crowley is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

"Chris Hornbeck" wrote ...
I have an Intel "wafer" from back in the 486 era, when Ginny
was still teaching and Intel provided it along with some other
elementary school materials. The dies, if separated, would be
about 0.65 cm x 0.75cm and the bisquit itself is a little less
than 15cm circumference. No clue what it is.... hint, hint...


Wow, that is an oldie. We went from 150mm (6-inch) to 200mm
(8-inch). Today we have more 300mm (12-inch) fabs on my campus
(in Hillsboro, OR) than anywhere else on the planet. The next step is
450mm (18-inch) wafers. But I can't reveal when that will be. :-)

These days, wafers at any step of processing are considered trade-
secret intellectual property and are treated like secret documents.
They sure don't hand them out anymore. You have a collecor's item.
I wonder how much it is worth? Do they sell them on eBay?

If you examine it under a strong enough microscope, you should
be able to read some kind of text identifying what it is. You might
be able to identify it by image and die size from public info online.
I turn to Wikipedia more often than internal sources to identify
chips. It is more straightforward and I can't get into trouble for
accessing classified internal info without a "need to know". :-)


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Scott Dorsey Scott Dorsey is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

Richard Crowley wrote:
"Chris Hornbeck" wrote ...
I have an Intel "wafer" from back in the 486 era, when Ginny
was still teaching and Intel provided it along with some other
elementary school materials. The dies, if separated, would be
about 0.65 cm x 0.75cm and the bisquit itself is a little less
than 15cm circumference. No clue what it is.... hint, hint...


Wow, that is an oldie. We went from 150mm (6-inch) to 200mm
(8-inch). Today we have more 300mm (12-inch) fabs on my campus
(in Hillsboro, OR) than anywhere else on the planet. The next step is
450mm (18-inch) wafers. But I can't reveal when that will be. :-)


With technology like this, why the hell can't I get decent discrete
transistors? All I want is a 2N5088 that is really a 2N5088 and not
some wacky noise generator.

These days, wafers at any step of processing are considered trade-
secret intellectual property and are treated like secret documents.
They sure don't hand them out anymore. You have a collecor's item.
I wonder how much it is worth? Do they sell them on eBay?


I used to write code on a CDC Star-100 computer which had the actual
wafers mounted uncut inside a box and all the leads tacked from one
point on the wafer to another. And I can still get die-cut bare
chips for a lot of things, so why can't I get the uncut wafers?

If you examine it under a strong enough microscope, you should
be able to read some kind of text identifying what it is. You might
be able to identify it by image and die size from public info online.
I turn to Wikipedia more often than internal sources to identify
chips. It is more straightforward and I can't get into trouble for
accessing classified internal info without a "need to know". :-)


Yes, it should say something like iAPX432 on the side of each chip....
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Richard Crowley Richard Crowley is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

"Scott Dorsey" wrote...
With technology like this, why the hell can't I get decent discrete
transistors? All I want is a 2N5088 that is really a 2N5088 and not
some wacky noise generator.


You know the amswer. The people who sell them don't think
there is a suficient commercial market to warrant fabing them.

Discreete transistors can be made profitably on pretty small
wafer sizes. And there should be lots of small (3-inch, 4-inch
even 6-inch) tools out there that have been replaced by larger
ones. But even if you could get the equipment for free, it still
costs a lot to run a cleanroom. Not to mention whether you
could get the plans/masks for those old products (or spend
$$$ to reverse-engineer them with some time on a SEM.
I can't say that I'm surprised that there aren't more companies
out there still making legacy discrete semiconductors.


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Scott Dorsey Scott Dorsey is offline
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Default Turntable "suspended in a vacuum" to prevent vibrations?

Richard Crowley wrote:

Discreete transistors can be made profitably on pretty small
wafer sizes. And there should be lots of small (3-inch, 4-inch
even 6-inch) tools out there that have been replaced by larger
ones. But even if you could get the equipment for free, it still
costs a lot to run a cleanroom. Not to mention whether you
could get the plans/masks for those old products (or spend
$$$ to reverse-engineer them with some time on a SEM.
I can't say that I'm surprised that there aren't more companies
out there still making legacy discrete semiconductors.


Hell, TI and Fairchild didn't have cleanrooms when they were making
big discrete transistors. Transistors, Inc. even took a while before
they figured out it was important to prevent assembly technicians from
smoking while they worked.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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