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#1
Posted to rec.audio.opinion,rec.audio.pro
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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. |
#2
Posted to rec.audio.pro
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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." |
#3
Posted to rec.audio.opinion,rec.audio.pro
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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. |
#4
Posted to rec.audio.pro
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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 |
#5
Posted to rec.audio.pro
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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." |
#6
Posted to rec.audio.pro
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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 |
#7
Posted to rec.audio.opinion,rec.audio.pro
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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 |
#8
Posted to rec.audio.pro
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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. |
#9
Posted to rec.audio.opinion,rec.audio.pro
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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/ |
#10
Posted to rec.audio.pro
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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." |
#11
Posted to rec.audio.pro
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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 |
#12
Posted to rec.audio.pro
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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." |
#13
Posted to rec.audio.pro
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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/ |
#14
Posted to rec.audio.pro
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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 |
#15
Posted to rec.audio.pro
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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. |
#16
Posted to rec.audio.pro
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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 |
#17
Posted to rec.audio.pro
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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". :-) |
#18
Posted to rec.audio.pro
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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." |
#19
Posted to rec.audio.pro
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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 $$$ to reverse-engineer them with some time on a SEM. I can't say that I'm surprised that there aren't more companies out there still making legacy discrete semiconductors. |
#20
Posted to rec.audio.pro
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Turntable "suspended in a vacuum" to prevent vibrations?
Richard Crowley wrote:
Discreete transistors can be made profitably on pretty small wafer sizes. And there should be lots of small (3-inch, 4-inch even 6-inch) tools out there that have been replaced by larger ones. But even if you could get the equipment for free, it still costs a lot to run a cleanroom. Not to mention whether you could get the plans/masks for those old products (or spend $$$ 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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