Opus 3 Cantus parallel tracking arm

[moray james]

if the arm has only two balls in the trolley assembly and works this well you have your proof and i would not argue that it works very well. From the first photo I saw I was thinking about the Souther arm and another design which is very similar but which uses a captive air bearing that was patented in the early 60's I think. In my mind I cannot help but think that a three point contact trolley would have a stability advantage as well as a possible structural advantage thought it will add mor to the moving mass. The inside sheltered position of the trolley is a clever idea as even normal amounts of house dust will catch up to you. You need a clean machine.
I thought about the comment on the ars range of motion and why that was special, the arm does not move up and down it only moves forwards and backwards and horizontaly. I tried to recall listening to Lou discribe how his arm worked and his answers to my non understanding questions. I think I have ben able to answer one of my own questions. A longer arm geometry would not be good as it would move towards the cartridge moving up and down and you want ti to move forward and backwards so it can track the surface if the record in a parallel manner.
If I am getting a better understanding of this arm please feel free to further enlighten me and if i am off bass please correct me. If you have some clear photos or drawings of the trolley I would very much like to see them so I can get a better understanding of this arm. Lastly I seem to recall Lou Souther telling me that a very short arm was necessary and desireable, the cantus is longe than Lous arm could you comment on that? Thank you and a special thanks to Peter at Pentacone for his help in discribing the arm and for telling me about the slot at the back. I was starting to feel like the mind freak was making this thing work.

[Pentacone]

Hello Anders,

I tried to tell Opus3 about you....and he said "Anders" is my Very Good Friend from "long Time"

I wish he could speak proper english like wht I do...!

LuvP.

PS. Thanks for teaching the "Trying" Afficionado's, a little further on their paths. It might only take the thirty three years that I have been Trying to understand!!!

P.

[Pentacone]

Are you going to tell everybody...like I told you privately....Or am I???

Do not forget, at this stage, that our 12 Hour conversation was Private!!!

Who has told them about the secret slot....did you have permission to let them know....IDIOT??

And don't , for G*d's Sake let them in on the Dust!!!

Now look, just between me and you...Forwards and Backwards is from the Back of the Turntable Chassis towards the Front...NOT across the Platter to the Spindle!! I hope I've made myself CLEAR NOW!!

And Opus3 will NEVER allow you to see a Diagram...no matter how nicely you BEG!!

Now, just so you realise that I am spending a Fortune attempting to help you create your own Arm...The trolley is so stable, it does not Move at all!!!

Anders, Can you explain this any clearer? I seem to be having a bit of trouble!!

By the way, the Glass Tubes swings around quite easily, thus making it MUCH better than the Pathetic Souther!!!

Poor Lou, if only he listened to Mr OPUS.

T.T.F.N.

P.

[Cal Weldon]

Peter,

We have rules here about verbal abuse. If you guys had a conversation offline then please continue to deal with it offline.

Thank you.

[Pentacone]

Please explain what I said that offended, and I will do everything I can to Repent

Thank You.....With GOD's Love.

[Nanook]

Moray,

the Cantus looks interesting. I can pretty well backwards engineer it if you like. ...but----three bearings can create a "wobbly leg" effect. If running on a plane (flat surface) then yes 3 is better than 2, but in the tube... I think 2 are better than 3.

stew

[moray james]

so the assembly you are suggesting would consist of two ball in cup bearings which are mounted to either end of a rectangular plate, one bearing turned up at one end and the other bearing turned down at the opposite end. And if I follow Andres the bearings would be offset from the centre line of the rectangular plate so one bearing tip on one side of the plate and the other bearing tip on the opposite side of the plate. Two holes in the plate to mount the rods that insert into the tube via the slot.
I suppose you could also mount the bearings in the exact centre of the plate with one bearing on the front side of the plate pointing up and the other bearing on the other side of the plate facing down. But this orientation depends upon perfect balance of weight on the two rods. If you place the bearings at the ends of the plate it ought to be more stable.
Am I making sense? Is this what you had intended? Have got to learn to use sketchup so I can draw what I am thinking.

[Nanook]

asketchup has a bit of a steep learning curve. I've been using it for over a year and I still mess things up. I'll sketchup what I mean later...

stew

[moray james]

I figure that this arm has been in production (and so in the public domain) for what must be twenty years? DIY eats very little if any of a manufactures sales. I am considering ideas for a similar arm not a copy. That said knowing how the Cantus is designed would be very educational. The likelyhood of my ever building one of these is VERY little as I need a new project like I need a hole in my head. Personally I would be more inclined to purchase a prebuilt unit but the design concepts fascinate me. On the other hand crude tinkering to prove concepts could be entertaining. A good example is the Ikea arm design. To take such a project to the point of being the equal of a production unit is a huge task and one I would prefer to leave to the manufacturer.
Thanks Nanook I look forward to your sketch. Regards.

[directdriver]

I apologize if I am being redundant but I want to point out again the reason Souther/Clearaudio tonearm resting on three rollers , which make a plane, is to lock in for horizontal movement only to ride on the two quartz rails and vertical movement is taken care of at the gimbal bearings below at the hanging mechanism. If one is to use two rollers, it would create a rocking front to back motion, thus the vertical arm movement. My concern with the Cantus arm is that the two rollers are cylindrical and seating on a glass tube would create too much contact points, at least four. Wouldn't it be better to have V-grooved rollers riding on a blade, therefore less contact, less friction and more precise vertical pivot? Just a thought.

I do like the simplicity of the Cantus design - anything that does not require an air pump is thumbs up in my book. I wish we can explore more options in the pursuit of tangential tracking without resorting to air-bearing ad nauseam. It's more fun and inventive to come up with non-air-bearing designs, such as rails, rollers, magnets, multiple pivoting (Thales tonearm), hinges, etc, etc...

Here's fellow in Japan uses linear motion ball bearing bushings to make a linear tracker.