2020 update : JC Verdier La Platine

hi @ledoux1238 yeah it was a big deal for me.  i replaced both.  it just got so easy when i find them online and the post was so quick.  i imagined glue and all sorts of things.  not the case.

the magnets that came in the "collars" had an outer dia of 185 and inner dia of 95 mm (20 mm thick).  the magnets couple to the steel "collars".  to remove the old ones was easier.   less powerful.  somehow i could lever with a cloth and screwdriver and up they would come.  i needed the cloth less i fracture the ferrite.  

installing the new ones which are Y30 ferrite and 180 mm OD and 100 mm ID (20 mm thick) was tricky because very difficult to remove once in the collar.  very strong.  nothing much to grab once they are flat on collar.  i put a magnet in wrong (opposite polarity).  to remove it was very tricky.  i ended up using wideset long handle pliers and a soft cloth.  you just need to get an edge up.  adjusting position also very tricky but very necessary to optimise wobble.  also more powerful magnets made it very tricky to assemble the la platine.  that is putting on top platter assembly, now more powerful magnets will push the bottom assembly out of alignment unless i am very careful.

i have got a factory in china now making me another 2 sets of magnets but these will be Y35 ferrite which is stronger and longer lasting.  i anticipate it will be about 25% stronger and also will have dimensions of 190 mm OD and 89 mm ID so as long as i can get them in, i will really have better magnet coverage in the collar and stronger magnets hence more repulsion in aggregate.

it is dubious whether more repulsion will do anything good for me.  i mean alot of people run the platter just resting on the ball so does it matter if there is a 1 mm gap versus a 10 mm gap versus 20 mm?  i guess the way i see it is i don't anticipate an impact on stability from less bearing being in top platter assembly but i think we could have less noise and less friction.

@mr_gray 

I just did a quick online search, and Y30 or Y35 ferrite magnet discs of varying dimensions are readily available!
On the old Verdier web-site JC Verdier spec’d  out the type of carbon steel used, TELAR 57 of ARMCO, which have the suitable magnetic properties for use in his TT. What is the connection of the Y30 ferrite to ARMCO steel type? I just do not know my metallurgy that well. 
And correct me if I have misread your post. The aluminum platter and the magnet are attached by magnetic attraction, no adhesives are involved? I had been taught that magnets do not interact with aluminum, hence the question. 

Regarding the strength of the magnets , a Dutch audio dealer, Callas Audio, came out with a limited addition mod kit for the La Platine. It could varying the amount of magnetic force. The result of which is better bass response. Some user would use the ball as a corrective against the magnetic force. 

@dover  Eclipse motor + Road runner sold as a kit from SOTA does not come with a housing. Additional costs with a custom housing and a separate linear power supply would have to be factored in. As @lewm had advised,  I will shot a quick note to Donna at SOTA and Bill Carlin regarding magnetic interference when the time comes. 

the platter is attached to a steel collar below and it is that to which the magnet affixes.

the callas mod was all about being able to fine tune location of bearing (vertically).  with the granito i have that adjustment via a bolt beneath the table.  just need long spanners to get to it (size 17).

belts arrived today.  i can't get the platine to spin slow enough now (HA!).  but of course this is simply highlighting that i haven't the correct lubricant.  i am using a very light synthetic lubricant.  it is too light.  as per JC Verdier's design i will now use ROCOL X5 Ultraglide.  This will create a little resistance which will mean i will come into a better place for achieving speeds i need but also the drag obviates stylus drag as per Verdier's design.  i wouldn't be surprised if it makes it a little quieter too as i think it will be slightly dampening.

transrotor belt is skinniest.  gold ring is a mm or 2 thicker.  ebay EPDM belt is grossly thick.  they all seem to achieve the same results at this stage.  Wow no better than 0.04 rms.  speed variation down a little but still about 0.15 rpm absolute.  hope to improve both these numbers with the right lube.  i have 5 kg coming so if anyone needs some, please reach out (or if anyone needs magnets).

@ledoux1238 i must admit i have trouble working out how armco telar 57 lines up with Y30/Y35.  i will say though that Y30 even in the size is used (which is smaller than what could fit in collar) has enough magnetic force to do the job even with my additional 3 kg on there (weight and SDP thing).  having said that, i am keen to try Y35 as more float is something i'd like to see.

based on installing Y30 - even more force will be difficult to manage.  i don't imagine that JC Verdier design needs much more than Y30 based on my experience.  it seems a good match for the original.  i had heard from the gentleman i bought my table from that the original magnets came from Focal drivers (a 38 cm driver from the 70s as i recall?).

@mr_gray 

Thanks for the further explanation, crystal clear. The outer ring collar  attaches to the platter, and prying will release the magnet from the platter. Who would have known without your actual tinkering? 

I know you have a lot on your plate right now, but have you also played with mats? I have been using a Micro Seiki cu 180 copper mat for the past few years. But last week decided to remove it and play nude. I like it without the mat!