PTP5 Stealth - project "Khufu"

[DeccaSG]

I've well and truly caught the Lenco bug
My acrylic L75 has barely had time to get it's feet under the table but I've now (almost)finalised my plans for a Super Stealth inspired upgrade.

My design goal is to create a visually exciting table with an emphasis on sonic excellence. Basic concept is to utilise the following.
1. PTP5 mounted in a heavyweight hardwood split plinth.
2. Mammoth super bearing secured to top and bottom plinths.
3. Isolated tonearm pod/plinth.
4. Stacked acrylic platters.
5. LMC (Lenco Motor Controller)

I want to eliminate/control the adverse effects of unwanted vibrations wherever possible, and control the dispersion of such interference whilst considering the interactions between the key components. "A grounding stratedgy for vibrations" for want of a better phrase. The ground in this instance is my hifi rack. All this needs to fit with my visual design so there may be the odd compromise but these should be kept to a minimum.

The bearing will be clamped to the top and bottom plinths. My thoughts are that this should mean that some of the bearing noise will be fed directly downwards and away from the top plinth. The connection between the top and bottom plinths will be via threaded M12 rod screwed into tapped holes in the hardwood.

As you will all know the motor top plate is isolated from the bearing top plate with the PTP so thats a good start in eliminating motor rumble and interaction with the bearing. My plan is to mount the top plinth so that it has it's own route to ground. It will likely have it's own supports but will need to be fixed to the bottom plinth in some fashion for overall rigidity.

The arm pod/plinth will bridge the main TT body. I thought about keeping this completely isolated but positioning is critical for accurate alignment of the arm and cart. A remote board is ideal to remove effects from the plinth etc but could have the tendancy to move (even if it was ever so slightly) and I would be forever checking it's alignment. Initially I'll be resting this via spikes onto the top plinth but this will not be a permanent fix so I can refine the design as time goes by.

I like the look of stacked platters and the theory that this gives some sonic benefit due to it's isolating mass. The new bearing will hande the extra weight with ease and I can experiment with platter height if necessary.

The Stealth plates are not here yet (crossing the channel as I write) and I've just finalised my spec for the bearing with Jeremy.

I'd welcome any thoughts and input to my plans. Help or ideas on how to isolate the arm board would be particularly welcome. I'll knock up some quick drawings so y'all can better visualise what I'm attempting to achieve. For now here's some of the materials I've gathered to start the build process.

45mm "Amazque" Hardwood.
50mm squared rod of "Cocobolo"
20mm Acrylic sheets.


Cheers all,

[autobayer]

Uuuh.
That does already look so cool, I can´t wait to see how you get along with it.
 

[fasterbyelan]

Lots of photo's please, it's good to see how things are put together.

That wood should look superb!

Karl

[Sarchi]

VERY interesting, Allan.

Wanted to confirm some things that weren't clear for me.

Are you sourcing the platters from somewhere, or do you plan to make them yourself?  I see a lot of acrylic in that pic, but making a balanced wheel from acrylic is no small feat.

The idea of clamping the bearing twice is really interesting.  I will be following that one closely.

Lastly- I am in the same mindset on tonearm pods.  My current thought is to cut a cross section out of the main plinth, for the "tonearm plinth" to slide into.  They could fit snugly (to give peace of mind about cartridge alignment), but would be decoupled with at least some cork, foam adhesive tape, or whatnot.  Let me add a crude drawing of what I mean.



(would look a lot better round as opposed to a triangle, but would be harder to cut...at least for someone like me)

But of course this approach is "limiting" in that if you want to go for a bigger arm, or use the main plinth in a different way, it will look like hell.    Another way is to make the pod as heavy as possible, and "mark" the shelf surface for it, e.g. drill some small dimples so that the pod's feet sit in place at the perfect alignment spot.  (and yeah then you have to make sure the turntable itself doesn't move either)

[ropie]

Another way is to make the pod as heavy as possible, and "mark" the shelf surface for it, e.g. drill some small dimples so that the pod's feet sit in place at the perfect alignment spot.

Nice idea.

[DeccaSG]

Are you sourcing the platters from somewhere, or do you plan to make them yourself?  I see a lot of acrylic in that pic, but making a balanced wheel from acrylic is no small feat.

Lastly- I am in the same mindset on tonearm pods.  My current thought is to cut a cross section out of the main plinth, for the "tonearm plinth" to slide into.  They could fit snugly (to give peace of mind about cartridge alignment), but would be decoupled with at least some cork, foam adhesive tape, or whatnot

Another way is to make the pod as heavy as possible, and "mark" the shelf surface for it, e.g. drill some small dimples so that the pod's feet sit in place at the perfect alignment spot.  (and yeah then you have to make sure the turntable itself doesn't move either)

Thanks Noam, some good ideas. Yes I'm cutting the acrylic myself with a router and circle jig. I get it really cheap so nothing to lose. I believe that the structure of acrylic is consistent and sound so balancing should be ok. It can't be worse than the orignal Lenco platter 

I wondered how others fixed/secured their pods.
The tonearm (my Transfi Terminator) will have it's own plinth mounted above the TT plinth. It will be as large as the TT and made of 20mm acrylic so will be very heavy. It will have it's own spiked support rods that I can rest in dimples in the main plinth body. Thanks for the tip.

Here's a cross section pic of what I'm aiming to do. Should make things a little clearer. 

[Sarchi]

Great mockup, that is very clear.  And I admire your plan to make platters....very bold.

But just to challenge one premise - in my opinion, if the tonearm plinth is coupled in any way to the main plinth, then why not REALLY couple it, or make it integral?  I may be missing the point, but to me, the idea of the "island" tonearm pod is mainly to decouple it completely, like you would with a motor-controller pod.  (I guess the side benefit being that you can also easily move it for duty on multiple turntables...)

[DeccaSG]

Great mockup, that is very clear.  And I admire your plan to make platters....very bold.

But just to challenge one premise - in my opinion, if the tonearm plinth is coupled in any way to the main plinth, then why not REALLY couple it, or make it integral?  I may be missing the point, but to me, the idea of the "island" tonearm pod is mainly to decouple it completely, like you would with a motor-controller pod.  (I guess the side benefit being that you can also easily move it for duty on multiple turntables...)

I did ponder taking the rods up through the main plinth body and into the underside of the arm plinth. That would be solid and coupled as you say, but not easily constructed or adjusted.
I like the idea of a removable pod. Easy to add and I can adjust the height easily should I add or remove platters. Not completely decoupled but almost.
The other option is to make the arm plinth wider than the top plinth of the main body. That raises the question of fixing/postioning of the pod again and why I asked for ideas on the options.

Lots of thing can be tweaked or modified as I go through the build. I need to decide on plinth shapes and have a few decisions to make on other materials I will use. The beauty of the seperate pieces is that I can try them and mod different aspects as I go. I won't be stuck (wrong word really) with a rigid design. It can still evolve 

Plenty of planing, sanding and cutting to do on the plinths in the meantime. I should make some steady progress this weekend and I'll post some more pics when I can.

[hatehifi]

Another slpendid looking (and sounding) one, eh Allen?! Just tagging to follow your thread. Best of luck!

[gthang]

Cool design, Alan.

No doubt this will be a stunner. looking forward to seeing the project develop.

[jon]

The arm pod/plinth will bridge the main TT body. I thought about keeping this completely isolated but positioning is critical for accurate alignment of the arm and cart. A remote board is ideal to remove effects from the plinth etc but could have the tendancy to move (even if it was ever so slightly) and I would be forever checking it's alignment. Initially I'll be resting this via spikes onto the top plinth but this will not be a permanent fix so I can refine the design as time goes by.

If your arm pod is sufficiently heavy it will not move. Check out Candy for my approach.

The only thing you will need is some sort of protractor or jig to allow for quick and easy set up. I have a Dennesen Protractor which suffices for me.

Anyway the concept looks interesting, good luck with the build!

[DeccaSG]

If your arm pod is sufficiently heavy it will not move. Check out Candy for my approach.

The only thing you will need is some sort of protractor or jig to allow for quick and easy set up. I have a Dennesen Protractor which suffices for me.

Anyway the concept looks interesting, good luck with the build!

Wow Jon, Candy is sweeeeeeeeeeeeeeeeet, I salute you.
I like the way you've shaped the plinth to match the PTP. Great styling and a quality finsh too.

A heavy arm pod is a key ingredient. This design should weigh around 2kg, perhaps more. I'll be sure to make the pod as heavy as I can. 

I'll be using the Transfi tangential arm so in theory the critical part will be getting the platter dead centre where it peeps above the arm plinth. I need to think up and create a jig to suit, Plenty of time so I'll give it some thought for now.

[jon]

Candy is enjoying an honourable retirement! She was blown into the weeds by the Black Prince.

I am also working on Jet

[DeccaSG]

Slow progress so far but the Stealth plates arrived today 
I've managed to start the top plinth and I've routed most of the cut out. The plinth still needs shaping and further fine sanding before adding a finish. Not decided whether to use beeswax, French polish or another oil as yet. Will do some testing on scrap first.
I've changed the design a little and now have a solution to completely isolate the tonearm bridge. I wont bore y'all with another diagram. I'll add new pics as I go. 
Updates soon 

[hatehifi]

First time I've had a good look at Peter's Stealth. Excellent job Peter! Oh, and your TT is already looking great Allen!