Opus 3 Cantus parallel tracking arm

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all these arms permit the tone arm to swing freely. this is exactly the action what Bo wanted to eliminate with the Cantus design.

You do realize the Cantus is a rather radical approach to tonearm design so you are not likely to another one like that, except the Statement TT1 arm by Clearaudio, who has a track record of curiously coincide with someone else's ideas. Surely there's a way to minimize the vertical seesaw action, right? Instead of V-groove bearing, can't we use regular cylindrical shaped bearing? Or even just some form of vertical fluid or magnetic damping in the vertical movement. I'm just trying to think of another way without using a rather delicate glass-tube. After all someone already thought of that idea so I want an alternative.

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I don't think that Rauna has had any real issues with the glass tube with respect to breakage and they are precision ground. Nothing to say you have to use glass you could machine and hone a metal tube to the same result. You could run two bearings outside of a precision ground tube but then you have to build a covering and when you use the inside of a tube it (the bearing and track) covers itself. Keeping the track clean is important. Designing the arm inside out would seem to be more complex than the way Bo did.
The use of the cylindrical roller bearings use in the current version of the Cantus is what makes the arm so rigid. The added friction in the horizontal plane is minimal and the extra contact points help the arm to better track a straight line. On a flat record the arm cannot rock there is no resonance because the system is non resonant. It is a very clever design. Motion is provided for the arm to track normal warps by means of the bearing races permitting the pivot point to slide enough to let the cartridge track the warp yet have no impact on horizontal motion.
 
That's a good idea but again there is no reason that the tube has to be glass. Remember the larger the tube the more rigid it will be. You will still want to cover the assembly. Riding on the outside of a tube does not however provide the inherent ability to centre the trolley if it is pushed off balance by a severe warp whereas the inside of a tubes curvature forces the trolley always back down to centre at the bottom of the tube. All the same I like your idea.
 
the inside of a tubes curvature forces the trolley always back down to centre at the bottom of the tube.

I agree that riding inside a C shape has much better self centering effect, hence geometrically more accurate.

Moray, I want to thank you for providing so much information on this fascinating design, especially quotes from the designer. I am beginning to have a better understanding the designer's intention and at first it was a shock to the system to think frictionless free vertical motion is not always a good thing! It really does make me see tonearms in a different light. It makes me addressing issue that I was not aware of. I applaud him for thinking outside the box.... or glasstube. :) Thanks again.


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I am contemplating a simpler design from this Thales pivot-tangential arm.

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Bo used to import the Sowther arm and was on very good terms with Lou. Lou's arm inspired Bo to make some improvements and the Cantus is the result of that. Lou sold his designs to Clear Audio and continued with them for some time. As far as I know Lou is still active but I don't know if he still does any work for Clear Audio.
As to the Tales arm well there are a lot of ways to skin a cat. Wonder what the moving mass is?
The more I look at the Cantus the more impressed I am with the thought that went into it. Simple is so complicated to do. Don't let the simple and plain Jane look of the Cantus fool you. The effort was not spared for the go but they did go easy on the show to make the arm affordable and that has to be commended. Unfortunately I feel the arm has not had the possible success that it might have had if it had the fit and finish of a Clear Audio Statement. Audiophiles cry for something wonderful for an affordable price but when it is handed to them they pass by because there is not enough flash and it can't be any good for that price. Oh well.
 
As to the Tales arm well there are a lot of ways to skin a cat. Wonder what the moving mass is?

According to their website, the original version effective mass is 11g and the heavier AV version is 20g. Very reasonable mass as the the entire arm employs pivot bearings and uses NO linear motion bearing at all.

The most important thing is to understand the theory of the Thales circle.


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I have studied its design for a long time now and it's really ingenious from a geometric standpoint. The only thing that bothers me is to have a pivot bearing right above the stylus that might affect its rigidity and noise. The less linkages and bearings the better, from an engineering and economic standpoint.

I want to eliminate the rod from M to C which in this case is the armwand itself but if look closely, the guiding rod from B to C is the actual part of the triangle and is C is always 90 degree to A. Therefore, my aim is to figure out an arm that is capable of changing lenth for couple inches. It's a tall order but with inventiveness and patience I think there's a way. I already have something in mind but I don't want to post until it's more refined in its design. Just a jumble of ideas in the head.

Tonearms are really fun. Pentacone, we don't need to sleep. :)


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Message to Mr.Wheldon

I have just seen, on your profile, that you are a "BIG" Speaker fan?

Please take a look at my Pentowther Horns (Google Pentacone).

Also, go through to Rauna of Sweden (off my site if you like) and see the present day Designs that Bo Hansson is producing (in Concrete).

If you like, I can scan some photo's that I have, of Horn Systems in Bosse's World (In Sweden).

Kindest Regards, and thanks alot for this DIY Forum.

LUVP.
 

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on some balls...

if you read the text, yes, the horizontal movement (lateral) is permitted by 2 balls riding in a track, and on an arm "carriage" , AFAI understand the patent. I skimmed it only, so no one needs to jump on the band wagon and suggest I'm wrong (I may very well have mis-understood what the text was referring to).

Murray, the longer I look at the Cantus, and the longer I look at the drawing (a rough sketchup) we did last year, the more I am convinced a similar arm could be done, but with exterior rollers rather than internal (I don't know how to cut a slot into a glass tube without destroying it, I have saved a tube for possible use though)
 
Nanook....Bosse supplied a Glass Tube for a past customer who had smashed his.

He charged around £50.00 ($77.00Cdn).

I am sure that he would be delighted in the thought that some was attempting to "Run" with his original inspiration.

He told me, the other day that he has sold 1,000 Cantus, World Wide, and this for him is quite enough for the effort put into the developement.

Let me know if you want one and I will do the necessary leg-work to get one posted to you.

LUVP.
 
Hi guys
I have'nt read trough the hole tread, but I saw you methioned the Opus3 Cantus
I am using The Cantus arm, on Bo´s Continous TT, and it works great
The glas tube MUST be absolutelly horisontal though
But ones it is set, it runns fantastic for years without further adjustments
Ones in a while I remove the "wagon" and pull a Cotton buddy throug the tube, to remove some dust.
But otherwise no maintenance, what so ever
A friend of mine ones oiled the bearings in his Cantus arm.
Never do that! The bearings must be keept dry to run easy.
Bo is very keen on good customer support, and he often offer seperate parts for the Diy'er. Just sent him a mail through the Rauna website
I ones broke my tube, and had a new one two days later.
Here's a pic of my Cantus (concrete TT), Canus arm and ZYX R100H Cart.
topp.jpg

Reg
Pix
Sweden
 
Hi Pix,

Great to hear from you....Welcome to "Our World".

Your command for English is very good....considering that you are Swedish.

Bosse can also do a good job with English, but struggles a little with Grammer when writing. So, he often sends the message to me for "Proof-Read".

I am quite happy to help you too, if there is any feeling of difficulty expressing your thoughts.

Just jot the words down on an Email, I will check the spelling and proper use of the language, and then pop it back to you for final examination, before posting to the "World".

Everyone will think you are incredible, and you will be able to learn a little more on how to say things, whilst thinking like a Yorkshire-Man!

With GOD's Love,

And Kindest Regards,

Pentacone Peter.
 
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