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Stanford University audio reference selection vinyl player

NHL99

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'Stanford University chose the Helix turntable unprompted, without Döhmann’s knowledge, over feted alternatives from Clearaudio, Kuzma and Goldmunds etc.'
 

Rednaxela

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The Helix was recently adopted by Stanford University as its audio reference to analyse vintage recordings from the Smithsonian archive
Surprised they use a turntable at all.

Are there no other techniques to extract what’s on the records they intend to analyse?
 

Mart68

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Surprised they use a turntable at all.

Are there no other techniques to extract what’s on the records they intend to analyse?
This ''The cartridge choice, however, is chosen for the emotional connection. It’s Stanford’s choice.”

Suggests that whatever they are using it for it's not very scientific.
 
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NHL99

NHL99

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Surprised they use a turntable at all.

Are there no other techniques to extract what’s on the records they intend to analyse?
One could guess that non-mechanical reading such as lasers would be the preferred choice. Maybe someone knows what is missed out by using laser?
 

DVDdoug

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Stanford does have unlimited funds so it's probably easy to convince a professor to buy the most expensive and exotic thing they can find and then depending on their position & connections they may be able to convince the university to spend the money. :)

The Library Of Congress is working on "contactless" optical techniques to digitize and archive various phonograph formats, including wax cylinders, etc. ...From that article it sounds like it hasn't been perfected and I'm not sure if's actually in use.

It turns-out that "regular" commercial optical/laser turntables don't work that well (they pick-up more noise than a stylus) but they don't cause record wear or damage.

...When I was a DJ on a college radio station in the vinyl days we had Stanton direct drive turntables and just about every radio & TV station or professional environment was also using Stanton. I don't remember the cartridge but it was probably Stanton too. Of course ruggedness and reliability are important in these applications, and they probably had relationships and a reputation in "the industry". And they might have special deals as a kind of product-placement to boost their marketing. I wouldn't be surprised if they were donated to our non-commerical state college station. We also had some HUGE JBL monitors in our little recording studio that we used to produce radio "spots" (no actual commercials) and I'm pretty sure those were donated.
 

Rednaxela

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The Library Of Congress is working on "contactless" optical techniques to digitize and archive various phonograph formats, including wax cylinders, etc. ...From that article it sounds like it hasn't been perfected and I'm not sure if's actually in use.
Thank you for the link. A very interesting read indeed.
 

egellings

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One could guess that non-mechanical reading such as lasers would be the preferred choice. Maybe someone knows what is missed out by using laser?
Didn't a company with a name similar to, if not, Finial Labs (sp?) come out with a laser tracking TT? Their slogan was "No needle; no wear" or similar. The machine loaded a record in much the same way a CD player loads a CD.
 
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fpitas

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One could guess that non-mechanical reading such as lasers would be the preferred choice. Maybe someone knows what is missed out by using laser?
The shark would have to be very nimble.
 

fpitas

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What's wrong with a laser is some guy figured he could unload a high-tech turntable on audiophiles. Obviously, a laser version, along the lines of the laser head to read/write BluRays etc, could be technically superior.
 

Avp1

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The shark would have to be very nimble.

One explanation I heard that visible light lasers have too long wavelength to effectively pick up the imprinted sound. Contact patch of elliptical stylus is around 3um. Wavelength of green light is about 500um. It is hard to make optics that reads the spot with that wavelength. They likely need to get into deep UV light to make it work. Coherent light sources for wavelength below 100um are not simple or cheap. Likely need to use synchrotron particle accelerator for that.
 

fpitas

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One explanation I heard that visible light lasers have too long wavelength to effectively pick up the imprinted sound. Contact patch of elliptical stylus is around 3um. Wavelength of green light is about 500um. It is hard to make optics that reads the spot with that wavelength. They likely need to get into deep UV light to make it work. Coherent light sources for wavelength below 100um are not simple or cheap. Likely need to use synchrotron particle accelerator for that.
That sounds...odd. The spots on a DVD or Blu-Ray aren't real big, either. The size of the stylus contact patch is only a vague indication of the size needed. The stylus diameter is around 0.6mil, according to this article:

These days you would use a modern blue laser, more like 400nM wavelength. That's 0.4uM.
 

Avp1

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That sounds...odd. The spots on a DVD or Blu-Ray aren't real big, either. The size of the stylus contact patch is only a vague indication of the size needed. The stylus diameter is around 0.6mil, according to this article:

These days you would use a modern blue laser, more like 400nM wavelength. That's 0.4uM.

In optical drives you have only two states to read. On LP you need to read large range of levels. For that light spot needs to be much smaller. You likely never saw a photograph of record groove done with optical microscope. All published ones were done with electron microscope. Required resolution is less than 100nm.
 

fpitas

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In optical drives you have only two states to read. On LP you need to read large range of levels. For that light spot needs to be much smaller. You likely never saw a photograph of record groove done with optical microscope. All published ones were done with electron microscope. Required resolution is less than 100nm.
Well, that explains why no one is doing it, I guess.
 

Jimshoe

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Didn't a company with a name similar to, if not, Finial Labs (sp?) come out with a laser tracking TT? Their slogan was "No needle; no wear" or similar. The machine loaded a record in much the same way a CD player loads a CD.
 

gene_stl

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One explanation I heard that visible light lasers have too long wavelength to effectively pick up the imprinted sound. Contact patch of elliptical stylus is around 3um. Wavelength of green light is about 500um. It is hard to make optics that reads the spot with that wavelength. They likely need to get into deep UV light to make it work. Coherent light sources for wavelength below 100um are not simple or cheap. Likely need to use synchrotron particle accelerator for that.
You have your micrometers and nanometers confused. Green light is about 550 nm . Blueray lasers are about 405 nm , 100um is in the far infrared. The 780 nm laser on CD players is 0.78 um. Near IR. But still readable by a silicon room temperature photodetector which is why we have CD players.

If you think you meant 100nanometers that is in the vacuum ultraviolet and causes rapid ozone generation and if you did shine that wavelength on vinyl especially black vinyl it would have an effect similar to strong acid. It is one of the things they use to remove organic molecules as well as dust specs from silicon chips during processing.

There are near UV (395 nm ) LEDs but I don't know about Lasers shorter than 405. The fact that those are used in Blu Ray players means they are MASS produced. Although lab lasers from china have become quite reasonably priced lately. Maybe they are already popping back up. I don't follow them anymore. Edit: yes, 405 seems to still be the shortest mass produced inexpensive laser wavelength. But according to the above the ELP uses red lasers iirc. The detectors are much more sensitive at that wavelength.

The electron microscope pictures are movies made with a series of still pictures and not actually real tracking. It IS possible to make identical pictures , optically using focus stacking. This issue is not so much resolution as it is combined resolution and depth of field. But neither focus stacking nor scanning electron microscopy can image things which are moving. The image is constructed in SEM by raster scanning. There are actually some focus stacking schemes that are getting quite fast but not fast enough to image a phono stylus.

The above you tube of the ELP record player sounded pretty good to me though it was a ytv. I would love to have one of those but they cost about $18,000.
 
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MoreWatts

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The ELP is currently discussed in another (turntable?) thread here, but I can't remember which. The laser apparently could not distinguish vinyl from dust and ended up being noisier than a regular cartridge.

Today's artist & album recommendation.
 
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gene_stl

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The fellow in the above ytv admits that records have to be spotlessly clean which makes perfect sense to me. Some styli seem to be able to plow through dust better than a sensitive interferometric beam of laser light , or five of them. Apparently two for the innergroove two for the outer groove and one centered.
 

antcollinet

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No one has mentioned the big problem with lasers. They don't sweep the crud out of the way. A stylus will shift dirt and dust from the groove as it goes - to the extent it sometimes builds up on the stylus if the disk is particularly dirty.

A laser sees every spec of dirt no matter how small or light - and "plays" it as though it is part of the actual music.
 

Rednaxela

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So we can read an analog record with a laser. Which means we can, for instance, build the laser and everything around it to do so.

To find out that dirt is the final showstopper?

Nah.
 

Mart68

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No one has mentioned the big problem with lasers. They don't sweep the crud out of the way. A stylus will shift dirt and dust from the groove as it goes - to the extent it sometimes builds up on the stylus if the disk is particularly dirty.

A laser sees every spec of dirt no matter how small or light - and "plays" it as though it is part of the actual music.
I have a review of the laser turntable, the reviewer ended up having to open up some brand new Beatles records he had been keeping as mint in order to get it to work acceptably. It was a daft idea and it cost about twenty grand.
 
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