DIY linear tonearm

[koldby]

Indeed a very elegant tonearm and filled with innovative ideas.
Mery Christmas every one.

[carlthess40]

Originally Posted by EAlex

Here is the last version of LC, which is on a turntable. It can be any turntable.
Testing has shown that this version sounds better, has more volume and better localization, better works out the unevenness of the plate. In the video, I put a piece of toothpick under the mat and shifted the center.
Three pivot points ensure stable contact with the guides, and the roller provides a secure footing and does not move off center. By changing the height of the roller axis, we easily adjust the VTA. The cart has become lighter, making it easier to roll. Making this option requires the least amount of work on precision equipment. When manufacturing, I buy suitable profiles from which I remove excess metal.
I will definitely use ceramic balls.
The ingenious idea of CARLO to put a parallelogram on a swivel base and install guides on it, allow making the cart with the cartridge as light as possible.

The 4 axis pivoting points is a wonderful idea
Are you open to building one of them for me ? I have a Victor motor/plater setup that I need a arm for. IMG_8513.jpg

[warrjon]

Originally Posted by carlthess40

I have a Victor motor/plater setup that I need a arm for.

Making an LTA that will perform as well as most pivoting arms is not difficult. The original 2 glass rod arm in this thread works extremely well. I built one to test and it out performed my Technics EPA100 and was made mostly from my scrap bin. The only thing I bought was a carbon fibre tube and borosilicate rods.

It's easy to make with hand tools, give it a go.............

[EAlex]

Merry Christmas! I wish you all happiness, health, and creative success!

[Bonfox17]

Merry Christmas!
Всем всего наилучшего!
Успехов в творчестве!

[hottattoo]

Merry Christmas, Boxing Day, whatever !!

Stay safe, happy, and keep up the DIY,
Joe

[warrjon]

Ditto...........

Have a great new year and lets hope 2021 is brighter. Although 2020 gave lots of opportunity for lockdown DIY.

[Mike56]

Happy new year to all, best wishes, Mike

[Mike56]

I have continued work on my radial tone arm development that has been posted here before.
I have made some progress that i thought might interest readers. All of it borrows extensively on the experience of other posters, thanks to all.
One of the features is that I make everything without precision tools and so, cut and made by hand and eye, all the various components need to accommodate inaccuracies on occasions.
I am quite content now with the non recirculating ball (ceramic balls on anodised rails) carriage with one primary rail to which the cartridge carrier is fixed and a secondary suspended rail that accommodates any variations between the two rails. This rides v on vee on simple anodised radial rails and is the lowest friction solution i have tried.
That deals with horizontal motion, until something else comes along………..
Vertical movement has seen various developments all derived from the parallelogram motion of the Roberval balance that as it moves vertically both keeps the angle of the mobile end (cartridge) constant and keeps the apparent weight (VTF) constant, all within operational limits of course and provided its properly executed.
I started with this oriented in line with the rails but quickly turned it 90 degrees to be in line with the grooves to remove some potential torque. First pictures show this orientation.
To start with i used a ball bearing motion which worked fine but was partly responsible (rattling balls) along with loose counterweights for a bass grumble excited by the cartridge in the groove.
That has been sent packing by removing any source of such rattles, which was recirculating BB’s and nut and bolt adjusters.
I then used Mylar hinges for several experiments but was always concerned about the lack of stability and decoupling, although they worked quite well, were easy to make and safe and tolerant. They were apparently very flexible but always caused a rise in VTF in warp movements. You can see pictures of some variants.
I then spent some time trying to construct a knife edge bearing parallelogram, which worked eventually on the test rig with magnets retaining the metal knife blades into the grooves. Even though i could turn the whole apparatus upside down without it coming apart i could never convince myself to commit a delicate cartridge to its tender care. Components are shown in the picture.
So i decided to follow the route of pentip pivots, many people have posted about these, just as the other parts above, its great learning from what other people have done.
There is little variation in VTF in the 3mm warp test shown in the two pictures below.
I made this using hot bent Lexan sections and the two sides of the pivot are held in place across the pentips by the spring of the channel section Lexan. It feels rock solid and confidence inspiring to handle. Last picture shows this playing successfully.
It all requires careful jigging but once again was executed by hand.
In retrospect a standard channel section of a similar material performance would allow me to start with consistent dimensions, but i quite like the appearance of the thermo-formed Lexan.
I am sure it could be improved, possibly reduced in size and weight, tighter tolerances etc.
Having played records i know well now for a couple of days I can now say this is the current best result, sound is tighter, open and detailed, more precise as well, just as one would expect with pivots with little play and better coupling.
I hope this is interesting and look forward to lots of interesting input and feedback.
M

[koldby]

Really nice writeup Mike.
And very nice work on the pen-tip sledge.
I am impressed by how many different ideas you are able to realize during a relatively short period of time.
Nice work and keep it up.