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Old 26th February 2013, 12:53 PM   #41
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Quote:
Originally Posted by Nanook View Post
stuartarm: 1/2" thickness increase for a solid platter is a huge amount of mass being added. I didn't see the underside of the platter, but am assuming it is a solid disk of material. If not machined out, then a lot of energy is wasted and contributes little to the flywheel effect vs energy applied.There are a couple of ways to get to the same result. Multiple motors vs. massive platter is one. The key is to conserve momentum.

Feet have been designed in so many iterations that somewhere feet must exist. If wanting to do something strictly custom because you can, that's OK. However unless you have some fairly sophisticated measuring equipment it is unlikely you will improve on existing designs.

I look forward to seeing the end result.
the underside is hollowed out to accommodate the large bearing assembly but i designed it that way to get center of gravity low on the pivot...like an inverted but not...most of the weight sits below main pivot...platter will rotate stable without plinth on a level surface in other words the feet on plinth will be just for leveling as well as to accommodate two different types of arm boards...almost done that part as well...wow
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Old 26th February 2013, 05:14 PM   #42
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I think using a solid lump is fine . I must do some wow and flutter tests doing it both ways . I suspect it won't make an once of difference either way . It is also cheaper to do . My guess is such things stop being important after about 5 lbs total mass . Most wow and flutter comes from poor quality belts and poor grip . Bearings obviously matter .

One thing seldom seen is a belt tentioner . Again to no avail if the belt has poor uniformity . The main advantage of multi-motor is to tension the belt . One pulley slightly smaller .

I have to say the concept of a flywheel with just enough power to overcome friction is a poor one . Verdier speaks of this in his very early writings .
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Old 26th February 2013, 07:04 PM   #43
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La Platine VERDIER

Also of interest one of his early designs . I owned one and can say it outperformed cult decks . The platter was anything but heavy . ERA Mk 6 .
https://www.google.co.uk/search?q=er...w=1280&bih=885
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Old 26th February 2013, 07:27 PM   #44
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Also ( pictures if nothing else )
Ralisation d'une platine de trs haute qualit, Verdier -1-
La platine Verdier, fabrication
platine
Retour sur la platine Verdier (J.C.Verdier)
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Old 26th February 2013, 11:40 PM   #45
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Many schools of thought, many schools of fish.

Nigel, are you saying that you prefer a stiff direct drive from a strong motor? In which case everything that effects the way the motor operates becomes hyper critical for sure. No doubt.

What I have observed thus far regarding the Garrard 301 and 401 is that most of the sonic "pleasure" appears to come from an upper midrange resonance in the platter (slightly different between the 301 and 401.

Obviously those who swap out the platters for aftermarket platters of various sorts effect the sonics as a result. Can't comment on that since I've not witnessed one of these yet.

So-called "rim drive" or "idler wheel" turntables are pretty tightly mechanically coupled between the motor and platter, and then through to the main bearing and on to the chassis. Can't have flex there at all.

A look at a record lathe shows both a heavy platter, stiff bearing (no flex) and a massive motor - out of necessity. It's not clear is this the ultimate playback method though?

So, I suppose that what ur theory of "pick up" is makes a big difference on what is thought best.
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Last edited by bear; 26th February 2013 at 11:51 PM.
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Old 27th February 2013, 10:27 AM   #46
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Over 15 years and no effort on my part the platter issue seems to be a blind ally , everyone wanted to sell us platters . I didn't like the 401 platter at all when I first saw it , gradually I realized it was not a prime factor . It is nice to have it better than the mass production Garrard version . Many will not know that the 301 and 401 platters were aged in the open for 7 months . The platters were rested between machining operations . And why not ? A bit of stock and storage is no problem . The 301/401 was produced at a loss in the summer months . Prestige product and was better than sending people home . They also made talking books for the blind gratis to keep people working .

I have heard many platters . Yes like make up it can complete a beautiful presentation .

Cutting lathes are not unlike a Garrard . Devices which somehow sidestep the usual problems . Logical and effective . They make first class turntables .

I dare say EMT is the proper reference we should all follow . I like the Verdier because it is guaranteed to work and easy to clone . I think the Garrard sound is more like real music if we take the Jazz element to be important .

It is interesting that you would think the platter would create artificial dynamics in the sound . I always was frightened it was rumble vibrato . That would have been a tough pill to swallow . Logically vibrato would do just that , it does with violins . No , I can categorically say it is not . 501 having - 79dB rumble ( verified , weighted ) has even more dynamics . It also has near perfect sidebands in the one frequency test ( like a sharp mountain peak ) . As someone said that is usually studio tape decks that can do that . That must mean something ?

Roy Gandy of Rega said ceramics are over looked as ideal platters . He had thought about it a lot and isn't given to saying anything usually . I told him phenolic plastics were my favourite .
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Old 27th February 2013, 11:04 AM   #47
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Click the image to open in full size.

I thought you might like to see this . It is a design by a friend of mine . It is how I would make a fusion of Verdier and Garrard . It also allows a cheaper motor to work better . The Thorens TD124 got it the wrong way around in my opinion . The flywheel needs to be after the motor and ideally via an idler .
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Old 28th February 2013, 06:20 AM   #48
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Yes, thanks for the image!

Very nice looking, and it appears to be well considered. I like the drive plan, clever. The belts are?

There is no doubt that the 301 and 401 platters impart a sonic signature to the sound. Very pleasant in the 301 for sure, great for jazz and vocals. Not totally neutral imo. I have not tried to measure it, but it's not difficult to hear upon audition as to what is going on.

Oh this one was in a heavy slate "plinth" (although I was under the impression that the plinth referred to the cover on a TT over in your part of the world? This could be gross misinformation from ancient times in the past based upon air)
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Old 28th February 2013, 06:30 AM   #49
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Quote:
Originally Posted by nigel pearson View Post

I have to say the concept of a flywheel with just enough power to overcome friction is a poor one . Verdier speaks of this in his very early writings .
I thought that the flywhell was used to stabilize the rotation
( sort of a buffer for digital...)
So in the pic I see a very little flywheel; it should be >= than the rotor, nah ?
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Old 28th February 2013, 08:34 AM   #50
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The platter issue is easily resolved . I was reading the Verdier again . The French is OK because it is technical French which will be mostly the same give or take a few words as English . I have to thank Mr V for defending what is seen as a nasty cheap material by many , Mazak in it's UK version . That coupled with the mass ratios of a TD150/LP12 does a lot to stop resonance .

The French company Audio Ref did a special mat based on the TD160 . If the original text can be found it showed a very deep understanding of the problems . One is enough damping to stop vinyl resonance without the very deep absorption of rubber . The humble Garrard 301 mat has mineral filler to help . The turntable I showed has a cork/neoprene composite ( my invention if turntables ) which has chaotic structure . It helps make a resonant system linear . If placed on a linear structure it remains linear . Scully cutting lathes have similar . If one wants resonance one makes everything identical . Very pure metals are by nature exactly that .

My friend ( above ) researched bearings . He found the advantages of a ceramic ball over a steel one to be debatable . The resonance of a customer research project was 1.5 kHz steel and 6 kHz ceramic . 40 kHz would be better . The last genuine Garrard turntable had a massive flat baring which tried to self levitate on a pressurized hydrostatic film . The look was that of a fancy cutting tool although optically flat . The flatness has to be 0.0001" of 90 degrees to stand any chance of working ( as a 301 ) . The 301 spindle was made on a Churchill centreless grinder which Garrard " forgot " to return after the war . The spindle size was from high grade detonator pins Garrard made , they had plenty of spare material . The length determined by the grinder size . Most other people grind on centres . This gives compound errors . Rega although cheap avoids that . The Rega bearing is a work of genius . I can say how to do that if anyone wants to know .

The Garrard spindle is only hard to 55 Rockwell , an LP12 about 64 . Used as Garrard intended is OK for 50 years service ( PYE records as I serviced their 301 which has run continuously , now Telestar in Hayes ) .

The flywheel effect I talk about is philosophical . Often people say it without any experimental experience . One forgets that the record is like a poor grade sandpaper . One has to find a way of making sandpaper rotate as if it is ice under the stylus . Please forgive any typos as I must now dash .
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