HI,
Some progress and one step back. Having the TT on a stand with wheels useful to see at 360 degree the TA and more easy the settings otherwise pretty complicated in my case.
Since I am not so confident it shall work well, before to use one of my DL 103 I purchase a cheap AT cart.
Rgds
Adelmo
Some progress and one step back. Having the TT on a stand with wheels useful to see at 360 degree the TA and more easy the settings otherwise pretty complicated in my case.
Since I am not so confident it shall work well, before to use one of my DL 103 I purchase a cheap AT cart.
Rgds
Adelmo
Adelmo,
congratulations on your progress. These arms are not easy, but you have gotten farther than most who have tried. I suggest at this point, leave the wires in a loose loop while you assemble, adjust, and test the arm. Very slight wire friction can be a problem.
Doug
congratulations on your progress. These arms are not easy, but you have gotten farther than most who have tried. I suggest at this point, leave the wires in a loose loop while you assemble, adjust, and test the arm. Very slight wire friction can be a problem.
Doug
Hi Doug,
Tks for the suggestion and for the past help too to you but also to all of the people of the forum. Now I understand it better, to have a steady TT and perfect levelling of the TA is really a must. I can level well the one by one all the components, the TT, the TA support and I also have 3 screw to further level the TA post. Since my accuracy as DIY is not good enough, I may need to reach an overall compromise on the levelling.
The wire I use are made of copper, 30 strands x 0.04mm diameter for each strand, covered by silk. Sonic wise they do sound pretty good and are also flexible enough. They come out from the arm wand in the rotation point, I will keep lose as suggested.
What seemed easy to make in reality is a present pending problem, it is the vertical bearing Supatrac style but with 2 pivots. It works well in vertical, but I have problem to set the TA at the neutral balance position, just lifting up a bit more and the TA goes out of gravity centre and drops towards the back.
Perhaps I have a too heavy arm wand and too high, combined to a too short strings.......
Shall try to figure it out these days.
In the mean time I have started to shape the magnetic cam using a 2.2mm soft steel wire and different mags in diameter and thickness to see the best combination. First 2 choice are Diam 4mm x 1.5mm and also 5mm x 1.5mm to see which one works better. I have tested the mags on the wire and seems that the vertical attraction is high, but can easily slide along the line of the metal wire. Shall see.
Tks n rgds
Adelmo
Tks for the suggestion and for the past help too to you but also to all of the people of the forum. Now I understand it better, to have a steady TT and perfect levelling of the TA is really a must. I can level well the one by one all the components, the TT, the TA support and I also have 3 screw to further level the TA post. Since my accuracy as DIY is not good enough, I may need to reach an overall compromise on the levelling.
The wire I use are made of copper, 30 strands x 0.04mm diameter for each strand, covered by silk. Sonic wise they do sound pretty good and are also flexible enough. They come out from the arm wand in the rotation point, I will keep lose as suggested.
What seemed easy to make in reality is a present pending problem, it is the vertical bearing Supatrac style but with 2 pivots. It works well in vertical, but I have problem to set the TA at the neutral balance position, just lifting up a bit more and the TA goes out of gravity centre and drops towards the back.
Perhaps I have a too heavy arm wand and too high, combined to a too short strings.......
Shall try to figure it out these days.
In the mean time I have started to shape the magnetic cam using a 2.2mm soft steel wire and different mags in diameter and thickness to see the best combination. First 2 choice are Diam 4mm x 1.5mm and also 5mm x 1.5mm to see which one works better. I have tested the mags on the wire and seems that the vertical attraction is high, but can easily slide along the line of the metal wire. Shall see.
Tks n rgds
Adelmo
Hi,
If I can manage to solder the TA wires to the cart clips I may start to risk a cart.
Rgds
Adelmo
If I can manage to solder the TA wires to the cart clips I may start to risk a cart.
Rgds
Adelmo
Hi,
I have lowered the counter weight therefore lowered the gravity center and now the double pivot vertical bearing Supatrac style works well. I can precisely balance the TA and it does not drops towards the back as before no matter how much I lift it up.. In the end if the TA working all well I shall search to have a better gravity center, not too low not too high, aiming that when a warp LP lift the TA the pressure in the cart do not increase much ( higher gravity centre ).
However, the wife now impose the summer vacation so I shall resume the whole thing after a while.
Tks n rgds
Adelmo
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HI,
I could not wait so long to return from vacation so I quickly put the TT in position and spin some records.
It track without skipping, but I surely need a fine tuning and implement the safety guiding cam so anyone can use it safely.
Rgds
Adelmo
I could not wait so long to return from vacation so I quickly put the TT in position and spin some records.
It track without skipping, but I surely need a fine tuning and implement the safety guiding cam so anyone can use it safely.
Rgds
Adelmo
Over the past two or three months, I have been playing with twin arm linear geometry and these two arms are the results. They are based on the Thales circle and tracking error is minimal. The geometry for these arms was actually straight forward, but the mystery was VTF. In order to get equal VTF across the record, it was necessary to split the CW between the arms and offset them vertically so they didn't interfere with horizontal movement. There are ten bearings, eight are coupled and pre-loaded.
The arms swing freely and smoothly and handling them feels the same as using a normal pivoting arm. My previous PLTs have a slightly unstable feel that takes some getting used to.
The plain wooden version is about 25 gr effM and an SC35C seems happy there. The other is about 15 gr and has a Sumiko Pearl mounted on it. There is no visible or audible mistracking with either arm. It doesn’t skate. I can’t explain that.
I studied previous similar arms - Burne-Jones, Van Epp, and Garrard Zero100 - but for various reasons, decided to see if I could find another geometry. I deliberately didn't look at Micha Huber's Thales designs at first, but did after I had a working design. His Simplicity design anticipates some of my solutions, but are too difficult for DIY.
I had invaluable support from nocdplz (Carlo) and Mike56 on this project. It was partly inspired by an amazing design of Carlo's for a linear tracking pivoting arm and his help with checking the geometry was critical. I hope the attached simulation from him is useable.
Doug
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Hi Doug,
very nice and impressive work, congratulation!
Any impression of the sound?
Regarding the instability feeling of the LT clone was due to mag missing attraction power or ....?
Did you try to change something in that area?
With mine I have to change the secondary bearing therefore make another pivot for it. I suppose I had slightly damaged the bearing during the assembling and I had some hesitation in tracking in a specific point. I am confident to fix it.
Again great job you did.
Rgds
Adelmo
very nice and impressive work, congratulation!
Any impression of the sound?
Regarding the instability feeling of the LT clone was due to mag missing attraction power or ....?
Did you try to change something in that area?
With mine I have to change the secondary bearing therefore make another pivot for it. I suppose I had slightly damaged the bearing during the assembling and I had some hesitation in tracking in a specific point. I am confident to fix it.
Again great job you did.
Rgds
Adelmo
Adelmo,
Thank you. It’s always good to hear from a fellow builder.
My current system is capable of producing music which I very much enjoy listening to and these arms have become part of that. I hope what I’m hearing is cartridges that are able to do their job as well as possible.
I think the difference in the operating feel of these arms is that there is no forward movement as there is in the Schroeder PLT or my two arm version.
I hope a new bearing solves the hesitation.
Doug
Thank you. It’s always good to hear from a fellow builder.
My current system is capable of producing music which I very much enjoy listening to and these arms have become part of that. I hope what I’m hearing is cartridges that are able to do their job as well as possible.
I think the difference in the operating feel of these arms is that there is no forward movement as there is in the Schroeder PLT or my two arm version.
I hope a new bearing solves the hesitation.
Doug
Simple, effective + good sounding: congrats, Doug
c
p.s. for that design more than Linkage program, you've to thank just yourself...
c
p.s. for that design more than Linkage program, you've to thank just yourself...
Hi Doug,
Hope so, for sure shall improve a lot as bearing damage was pretty clear.
In your LT clone do you have the safety cam that avoid/limit forward movements? In mine looks difficult to fit it due my poor design that should be revised in the dimension according to the TT. However mine was a kind of prototipe just to see if I could manage the system and make it working. In case of positive answer I may consider something dedicated to a better TT used just for this TA. Means I shall heavy modify the Lenco.
Rgds
Adelmo
Hi,
Changed a bearing with a spare one. Working much better now.
Made a kind of mechanical safety cam. has enough clearance to let the mag follow the wire track and to play free records, but providing a kind of safety.
Next I need a lifter to play with more safety with a better cart.
Changed a bearing with a spare one. Working much better now.
Made a kind of mechanical safety cam. has enough clearance to let the mag follow the wire track and to play free records, but providing a kind of safety.
Next I need a lifter to play with more safety with a better cart.
Ancient perplexity, maybe offtopic.
For our TAs we are all surely looking for the best possible ball bearings (I even try to stay away from them as possible).
So the most expensive ones, exotic materials, for the highest speeds.... (dentist drills >50k rpm!)
But aren't we making a mistake? going so fast they heat up, and therefore they must have the necessary play.
Ours instead turn 20° in ten minutes, wouldn't the laboratory instruments ones be better, with almost zero play; those made for precision actuators movements (eg microscopes or others?
c
Stiction, not friction is our concern imo - preloading, yes i know...
For our TAs we are all surely looking for the best possible ball bearings (I even try to stay away from them as possible).
So the most expensive ones, exotic materials, for the highest speeds.... (dentist drills >50k rpm!)
But aren't we making a mistake? going so fast they heat up, and therefore they must have the necessary play.
Ours instead turn 20° in ten minutes, wouldn't the laboratory instruments ones be better, with almost zero play; those made for precision actuators movements (eg microscopes or others?
c
Stiction, not friction is our concern imo - preloading, yes i know...
Hi Carlo,
Interesting topic, I suppose many shall agree with your opinion, myself as well.
For this reason in my rough LT TA clone I used on the vertical a kind of Supatrac bearing. Once set properly is simple and pretty good sound wise.
However, how about Flexure dual tipe?
In case is not yet available in the forum, you might open a new topic.
Rgds
Adelmo
Interesting topic, I suppose many shall agree with your opinion, myself as well.
For this reason in my rough LT TA clone I used on the vertical a kind of Supatrac bearing. Once set properly is simple and pretty good sound wise.
However, how about Flexure dual tipe?
In case is not yet available in the forum, you might open a new topic.
Rgds
Adelmo