Thirty three and a third.

[Spotted Horses]

I know that linear ones aren't anything new.  When did they first come out...1980's ?  Or late '70's?  Don't know.  If I'm recalling correctly, weren't they mass-produced?  But not nearly so much as the more traditional set-up?

Yes, a little googling indicates that relatively lowbrow linear tracking turntables were produced in the 80's. I seem to remember the most widely known one had the cartridge transport built into the cover, but Radio Shack had one with a tonearm on a moving pivot. The design wasn't adopted by the mainstream audiophile manufacturers like Thorens, then the CD deflated the market. At that point anyone who wanted actual good sound rather than a super elegant mechanical contraption went digital. (runs away)

[Spotted Horses]

The interesting discussion above brought to mind a demonstration of a Mag-Lev Audio TT I attended prior to the pandemic. Here are a couple of stock shots:







The platter rises like a UFO and is maintained by the use of magnetic forces.

That is truly bizarre. I guess the rational is that the spinning disk is isolated from vibration of the base. On the other hand, the restoring force that would keep the spinning platter centered would be very weak compared to a bearing. If something nudged it off center it would wobble back and forth, I think. Great for gawking at and photographs, not great for listening to records, I'd wager.

[Biffo]

Yes, a little googling indicates that relatively lowbrow linear tracking turntables were produced in the 80's. I seem to remember the most widely known one had the cartridge transport built into the cover, but Radio Shack had one with a tonearm on a moving pivot. The design wasn't adopted by the mainstream audiophile manufacturers like Thorens, then the CD deflated the market. At that point anyone who wanted actual good sound rather than a super elegant mechanical contraption went digital. (runs away)

I had one of those 'relatively lowbrow turntables'. It was part of a Philips midi system. The tone arm automatically moved to the correct position on the disc when you pressed play. It had some kind of optical tracking device that told it where to start. It was OK most of the time but I had a few LPs that must have been duller than the rest and there was no way I could get them to start at the beginning, not even by doing it manually. Eventually it became more and more cranky then gave up altogether. The rest of the system was fine for its price.

[Irons]

The engineering doesn't scare me too much. I would put the tonearm on a pivot, just like a conventional tonearm. But the pivot would be on a linear translation stage with a sensor that determines if the pivot has moved ever so slightly away from a perfect 90 degrees. When a deviation is detected, the pivot scoots over until the pivot angle is restored to 90 degrees. The scooting over has to be very steady and well controlled. If they can make a stage that keeps a read head aligned with a hard disk drive spinning at 9500 RPM, they can easily make a stage that keeps a tonearm aligned with a disk spinning at 33 1/3 RPM.  

The picture you attached appears to be along the lines of what I described. The difference is between a lone guru making a prototype and an engineering team developing a design for mass production.

Interesting. Isn't the elephant in the room there is not any physical contact with your disc spinning at 9500 RPM where as at 33 1/3 there is?

[Spotted Horses]

Interesting. Isn't the elephant in the room there is not any physical contact with your disc spinning at 9500 RPM where as at 33 1/3 there is?

You are correct that the requirements are not the same, but I wanted to draw attention to the speed and accuracy which is possible in a device that can be sold for $50. The head is positioned within a fraction of a micrometer (a thousand of a millimeter) with time scales in milliseconds.

Imagine the task. Suppose I gave you a turntable in which I had mounted the tonearm pivot on a linear track and you could move it along the track by turning a little crank. As the record plays you can turn the crank to keep the tonearm parallel to the groove. You could do that by eye. And what if I installed a sensitive optical sensor that detected if the angle between the tonearm and the groove was off by a tenth of a degree or so, and there was a little red light the would turn on if the angle exceeded +0.1 degree and a blue light that went on if the angle went beyond -0.1 degree. You could carefully turn the crank to keep the red and blue lights from going on. Now you just need a little stepper motor to turn the crank and a microprocessor to monitor the red and blue lights and adjust the crank a million times per second. That would be about $5 worth of hardware.

[vandermolen]

The interesting discussion above brought to mind a demonstration of a Mag-Lev Audio TT I attended prior to the pandemic. Here are a couple of stock shots:








The platter rises like a UFO and is maintained by the use of magnetic forces.

Amazing! I want one of those!

[Pohjolas Daughter]

Amazing! I want one of those!

Order immediately then...1 left in stock!  https://maglevaudio.com/collections/turntables

I found it interesting to read that you still need to have it on a (hopefully) vibrations-free surface (and obviously level too).

So, which of you gents will create something similar for CDs?  Or, how about one that will flip the LP over (without using an arm)...just using a magnetic field and automatically? 

PD

[Spotted Horses]

I think that the expression on this guy's face says it all:Here is a very short YT video which shows how it operates:

https://www.youtube.com/v/Ky0D00iyHAA

One thing I noticed in the video is that when they demonstrating the resilience of the levitation system by giving the spinning turnable a little tap it continues to wobble noticeably for some time, with a frequency that looked like about 2 Hz. I guess I'm supposed to be impressed that it doesn't fly across the room.

[aligreto]

Amazing! I want one of those!

I would definitely like to be there when you present the argument to your better half of the dire need to own a turntable with a levitated platter, Jeffrey 

[Spotted Horses]

I would definitely like to be there when you present the argument to your better half of the dire need to own a turntable with a levitated platter, Jeffrey 

She will agree if in return she gets a magnetically levitated salad spinner.

[Irons]

You are correct that the requirements are not the same, but I wanted to draw attention to the speed and accuracy which is possible in a device that can be sold for $50. The head is positioned within a fraction of a micrometer (a thousand of a millimeter) with time scales in milliseconds.

Imagine the task. Suppose I gave you a turntable in which I had mounted the tonearm pivot on a linear track and you could move it along the track by turning a little crank. As the record plays you can turn the crank to keep the tonearm parallel to the groove. You could do that by eye. And what if I installed a sensitive optical sensor that detected if the angle between the tonearm and the groove was off by a tenth of a degree or so, and there was a little red light the would turn on if the angle exceeded +0.1 degree and a blue light that went on if the angle went beyond -0.1 degree. You could carefully turn the crank to keep the red and blue lights from going on. Now you just need a little stepper motor to turn the crank and a microprocessor to monitor the red and blue lights and adjust the crank a million times per second. That would be about $5 worth of hardware.

I would take out a patent on that if I were you. $5 indeed.

Allow me to digress. A turntable is simplicity itself, a device that revolves at 33 1/3, that's it, nothing else! Yet engineers for over 70 years have wrestled with this seemingly simple task and they still haven't cracked it. Coming up with direct drive, rim drive, belt drive and what have you. A turntable (without arm) can cost $25 rising up to a six figure sum. The problem for designers is that the human ear can detect the tiniest fluctuation of a sound wave. I am tone deaf but can tell in an instant a flat note caused by TT "chugging". Turntables that have the capability to reproduce anything approaching the accuracy of CD in solo piano are few.

Your theory makes sound engineering sense, but.... We agree that a linear tracking arm on paper is superior and yet it has not taken over the market as it should. Why have not SME come up with one? The best and most expensive, including Len's, work with the arm "floating" on air. This raises another issue with noise from a compressor being obtrusive. Going back to my TT example, if designers are unable to get that right, they have little chance of achieving a moving as opposed to a fixed tonearm operating correctly. But just in case I'm wrong take out a patent!

[Spotted Horses]

I would take out a patent on that if I were you. $5 indeed.

Allow me to digress. A turntable is simplicity itself, a device that revolves at 33 1/3, that's it, nothing else! Yet engineers for over 70 years have wrestled with this seemingly simple task and they still haven't cracked it. Coming up with direct drive, rim drive, belt drive and what have you. A turntable (without arm) can cost $25 rising up to a six figure sum. The problem for designers is that the human ear can detect the tiniest fluctuation of a sound wave. I am tone deaf but can tell in an instant a flat note caused by TT "chugging". Turntables that have the capability to reproduce anything approaching the accuracy of CD in solo piano are few.

Your theory makes sound engineering sense, but.... We agree that a linear tracking arm on paper is superior and yet it has not taken over the market as it should. Why have not SME come up with one? The best and most expensive, including Len's, work with the arm "floating" on air. This raises another issue with noise from a compressor being obtrusive. Going back to my TT example, if designers are unable to get that right, they have little chance of achieving a moving as opposed to a fixed tonearm operating correctly. But just in case I'm wrong take out a patent!

I think the turntable itself is a non-issue. My father had a Thorens TD-124 (Vintage 1960 or so). I took it apart. It had an extremely massive metal platter which rode on a exquisite bearing, a polished stainless steel rod that fit into a precisely machined stainless steel tube with tight tolerance and a ball bearing on the bottom. The silky smoothness of the rotation of that bearing was a thing of beauty in itself. The drive was relatively crude. An electric motor with a rubber idler wheel which rode between a series or wheels of different size on the motor axel and a lip on the inside of the platter. With that bearing and that mass nothing was going to overcome the rotating inertia cause any measurable speed fluctuation. Later turntables I owned, mid-range Japanese table with direct drive and a servo and a very unimpressive belt-drive Thorens from the 1980s were much less impressive.

Based on my knowledge of physic and my experience with these machines, the crux of it is the tracking of the stylus with the groove. High frequency and high volume signal correspond with high acceleration of the stylus as it tracks the groove. The stylus is connected to a transducer (a  magnet or pickup coil) by a cantilever, and both the cantilever and the transducer mean that a substantial mass has to be moved when the stylus moves. in inertia of the cantilever and/or transducer can mean the stylus fails to stay at the bottom of the groove, or the cantilever can bend, or have mechanical resonances, which colors the sound. The Shure V15 Type V was the pinnacle of the technology in it's day, with a very high compliance transducer and a hollow beryllium cantilever with a high strength/mass ratio. The other sensitive issue is the tonearm, which is pushed along by the force the groove exerts on the stylus. It is important that tonearm have a very low friction bearing, so that the force required is minimal. I think the best turntable I had was the 1980's Thorens, because even though the table itself was a bit trashy, the tonearm was good. It had a good bearing and a carbon-fiber shaft with good strength to weight ratio. The tonearm cantilever combination can also have resonances, and the Shure Type V 15 Type V had a hydraulic damper to mitigate that. A good tonearm maintains stable pressure on the groove walls to help the cartridge do it's best.

[Irons]

I think the turntable itself is a non-issue. My father had a Thorens TD-124 (Vintage 1960 or so). I took it apart. It had an extremely massive metal platter which rode on a exquisite bearing, a polished stainless steel rod that fit into a precisely machined stainless steel tube with tight tolerance and a ball bearing on the bottom. The silky smoothness of the rotation of that bearing was a thing of beauty in itself. The drive was relatively crude. An electric motor with a rubber idler wheel which rode between a series or wheels of different size on the motor axel and a lip on the inside of the platter. With that bearing and that mass nothing was going to overcome the rotating inertia cause any measurable speed fluctuation. Later turntables I owned, mid-range Japanese table with direct drive and a servo and a very unimpressive belt-drive Thorens from the 1980s were much less impressive.

Based on my knowledge of physic and my experience with these machines, the crux of it is the tracking of the stylus with the groove. High frequency and high volume signal correspond with high acceleration of the stylus as it tracks the groove. The stylus is connected to a transducer (a  magnet or pickup coil) by a cantilever, and both the cantilever and the transducer mean that a substantial mass has to be moved when the stylus moves. in inertia of the cantilever and/or transducer can mean the stylus fails to stay at the bottom of the groove, or the cantilever can bend, or have mechanical resonances, which colors the sound. The Shure V15 Type V was the pinnacle of the technology in it's day, with a very high compliance transducer and a hollow beryllium cantilever with a high strength/mass ratio. The other sensitive issue is the tonearm, which is pushed along by the force the groove exerts on the stylus. It is important that tonearm have a very low friction bearing, so that the force required is minimal. I think the best turntable I had was the 1980's Thorens, because even though the table itself was a bit trashy, the tonearm was good. It had a good bearing and a carbon-fiber shaft with good strength to weight ratio. The tonearm cantilever combination can also have resonances, and the Shure Type V 15 Type V had a hydraulic damper to mitigate that. A good tonearm maintains stable pressure on the groove walls to help the cartridge do it's best.

Apart from "turntable a non-issue" (I own a Garrard 401) you have expressed the mechanics of record playing far better then I would hope to and would not take issue with the accuracy of your post. But the subject of the discussion - the viability of a linear tracking tonearm does seem to have been lost though.

[Spotted Horses]

Apart from "turntable a non-issue" (I own a Garrard 401) you have expressed the mechanics of record playing far better then I would hope to and would not take issue with the accuracy of your post. But the subject of the discussion - the viability of a linear tracking tonearm does seem to have been lost though.

It has! I can only say that I alway remember being frustrated by a clear increase in distortion at the end of a record. And there is the irony that for many pieces of music the end is a very loud passage vulnerable to distortion. There are several possible causes that I can think of. The tone arm geometry is worst at the end of the record, the skate force is largest, and the linear speed of the record surface past the stylus is minimum. Linear tracking would remove the first two, but not the third. I never owned a linear tracking turntable, so I can't say how big a practical improvement it is.

[Pohjolas Daughter]

I would definitely like to be there when you present the argument to your better half of the dire need to own a turntable with a levitated platter, Jeffrey 

She will agree if in return she gets a magnetically levitated salad spinner.

For 4-5,000 euros?!  I'd want a new kitchen!

PD

EDIT:  I did read some other interesting information (from the website)--one which was a very clever feature and another (which I had been wondering about earlier):

"Safety First

In case of power outages, the turntable has been designed with a UPS system, which stores enough power to safely lift the tonearm, stop the record, and return the platter feet to resting position. This way the turntable and record remain in perfect condition even when the unexpected happens.

Illumination

Subtle led lighting, in amber or white, has been added,  giving the turntable a sleek, futuristic feel, and further enhancing the visual effects of levitation even when the lights are off.

** NOTE: Because of the magnetic force used to levitate the platter, those with older pacemakers should not come within 1 metre of it, and magnetic media of all kinds should also be kept at a safe distance. See the User Manual for more details. **[/b]"   

PD

[Pohjolas Daughter]

Doing some record cleaning this morning.

Finally got around to cleaning a LP that a friend gave me over Christmas:  Steve Winwood's Arc of a Diver (See non-classical music listening thread).

Also, cleaned a mono highlights from Don Carlos with Stella, Cossotto, etc. with Santini on DG.


PD

[aligreto]

Illumination

Subtle led lighting, in amber or white, has been added,  giving the turntable a sleek, futuristic feel, and further enhancing the visual effects of levitation even when the lights are off.

PD

The "subtle lighting" reminded me at the time of something out of Close Encounters of the Third Kind 

[Pohjolas Daughter]

The "subtle lighting" reminded me at the time of something out of Close Encounters of the Third Kind 

Did you see the part about "those with older pace-makers..."  Gulp!

Listened to Side A of the highlights from Don Carlo....Wow!  I had forgotten how amazingly good some of those singers were (hadn't listened to much opera lately).  And so far impressed with the singers new to me.  Off to fix a cup of tea and then will play Side B.  The LP, by the way, has very nice liner notes (booklet really) that came with it (and was thankfully included by the originally owner).  Not bad for a buck!

PD

[Jo498]

Respighi: Pines of Rome.



Great sound. A tulips (edge of label) "Alle Hersteller" recording which has the reputation to be the best sound on DG. My copy is not a first pressing which has a red background to the stereo logo on front cover.

I have this on CD (in a Early Maazel box) and while I admittedly don't much care about these particular pieces, it sure sounds great. The LP also looks great and a beautiful cover. For technical reasons and laziness I never fully got into LPs (as I started listening as a teenager at the fading of the LP era int he late 1980s when CDs were just the thing), but they were and are so much more beautiful and collectible than CDs!

[aligreto]

Did you see the part about "those with older pace-makers..."  Gulp!

PD

I sure did!