Angling for 90° - tangential pivot tonearms

After watching the segment about DS Audio record center device, I am still not convinced that most of the records don't need center hole modification. Even if one out of ten records needs to be modified, it makes no sense to me.

I am also very interested in the last part of the video, Technics digital correction phono. If the digital sound is true to the analog sound, can we correct the eccentricity in the digital domain?
 
If I pay attention to my records being out of round, it seems quite alot of them
are slightly off with some way off center.

Since most of us just live with it and don’t point to an issue , I can imagine over time
with familiar records that there might be a more tightly focused image since the bearings
are not being constantly worked overtime with the music signals , but just speculation

If the price were cheaper I would be in.
They should provide small clear self stick centering labels so you don’t have be constantly
checking each record you play, but then again each side might be different from each other.
 
  • Like
Reactions: 1 user
After watching the segment about DS Audio record center device, I am still not convinced that most of the records don't need center hole modification.
The only way to avoid enlarging the hole is to make the bottom part of the spindle slightly smaller. The Nakamichi Dragon and TX-1000 turntables are done by nudging or shifting the platter slightly after calculating eccentricity with an detecting arm, so no modifying of hole nor spindle. Regardless, something has to be shifted to correct eccentricity. Annoyance of eccentricity is listener dependent. If it didn't bother the listener, just don't worry about it!
 
Ok, after a While uhps two years..
lets consider about why were trying to get an 90° angle:
The further sharp the diamond cut is, the more nessesary the angle is.
For example if your have a very sharp cut like a Shabiata or a van der Hul, if the angle is 1-3 Degrees the needle won't fit to the buttom of the groove. It would lift up and the Character of the needle would be more like a conical one, or worse, because the Needle is not finer over all angles but in one direction the longitudinal direction. So if the Pivot is not 90 ° the needle will lift up.
What is the Result?
Less contact to the flank of the groove and mainly contact to the waer out parts of the Groove. Or to be honest- you will add more wear and tear by doing so. Quality will theoreticaly increase when you use a Tonearm in 90 ° even with worn out Disks.
Is the Statement that Signals from right and left would divide in a range of measureble Outcome is that right, or is this effect negligible?
Greatings to this dead Threat.

My problems with lifting the arm are solved.
 
  • Like
Reactions: 1 user
The real doubtful one was VMS 30. It should have been the M20FL on paper. It was just lacklustre and not as good as the VMS5 to my ears. Unless you work with turntables and sell 1000's you never get to know this.
I was also underwhelmed with my VMS30mkII. I had high expectations when purchased top of the range cart. Interestingly, the stylus performed better in Ortofon F15N body. Eventually I got real thing, Goldring 1012.

Recently, for the sake of old times I revived the F15N body with Analogis allround E (black diamond) aftermarket stylus. After painfully long break-in, I got surprisingly interesting performance. This is how VMS was supposed to sound in first place.
 
Hi to all. Somehow happened I do have Garrard Z-100B in decent working condition as a gift. For now I'm using it as a second turntable for trials of different tonearms using the microscope chassis. I will upgrage the flimsy platter and it's low end bearing to much higher standards, and than I'll try to get the best of the Z-100 own tonearm performance, including with high compliance MM carts, and low compliance MC's. Will share the results here.
P1010304.JPG
P1010307.JPG
 
Last edited:
  • Like
Reactions: 1 users
Adelmo,

Please do build the the PLT you are planning and let us all know how it goes.

Boca Bearings - Search Results for sr3c-yzz #5 nb2

This link should take you to the bearings I used. They use a new very light lubrication and spin freely and quietly. If you don't want lubrication, just clean them in acetone.

If you are unfamiliar with pre-stressed bearings, I really suggest checking that out.

275mm/250mm are numbers I have for Frank Schroeder's PLT. Not a bad place to start.

Good luck with the arm and enjoy your holiday.


Hi Doug,

Happy and prosperous new year.

More than 2 years passed since our last chat, I failed to have a fly wheel well working as was supposed to be so as I mentioned I had started the work for the LT clone for my use. But after the ordered bearing where not delivered to me ( confiscated in Amsterdam for unknown reason ) I also stopped that project and made another different TA clone that I am using at the present.

Howver recently being in winter I decided to restart the LT project re checking the geometry, ordered new bearings ( hoping this time they delivery them ).
However even use the following dimensione I cannot get the cart make a straight line across the LP, no matter what I change there is a kind of curve.

Is it normal that there is a kind of curve or I just did not get yet the right geometry:

From vertical TA want to cart tip I use 250mm

From spindle center to bracket first pivoting center 275mm ; but I have also tried 280mm and other shorter and longer dimension. The 2 swing point of the bracket is 35mm, but I tried 38mm, 30mm and some other dimension.

I am in a loop without a solution to get a really straight line with the cart.

Therefore I cannot post any practical result so far.

Congratulation you all for the new proposition including Carlo s and others.

Rgds

Adelmo
 
I am in a loop without a solution to get a really straight line with the cart.
Hi Adelmo,

A happy new year to you too!

I really know what you're going through. Been there already ;)
Luckily, math, Excel and 300 lines of VBA code can do the trick.
I developed this file that can help anyone build their Schroeder LT clone.
What you need to get out of your "loop" is the red curve that my application generates.
Good luck and ping me if you need more details :)

Best regards,
Consty
 

Attachments

  • SchroederLT_Geometry.xlsm
    221.3 KB · Views: 60
  • Like
Reactions: 1 user
Hi Consty,

Thank you very much for the free support, appreciate it. Unfortunately my Mac Book cannot open your file correctly. I just see a picture from the patent, but nothing else.

Thank you again and best regards.

Adelmo





Hi Again,
Finally I manage to open the file. Figuring out how it works.
Ignore previous message.

Tks n best regards

Adelmo
 
Last edited:
Finally I manage to open the file. Figuring out how it works.
Great! For security reasons all macro enabled Excel files are protected by default. You must first enable it.
How it works: In the sheet Drawing there are four cells highlighted in green. Those are the input parameters you can choose.
After that, clicking the button PLOT will draw the red curve representing the magnet guide path and the whole tonearm in several key positions, according to the selected input parameters.
Sometimes you can get a message box asking you to change some parameters. That's because the values chosen at that time yield a physically impossible structure (for example a sine or cosine >1).
Good luck!
 
  • Like
Reactions: 1 users
Hi Consty,

Thanks again for the support. I have not been able yet to enable the calculation chart and input the wanted length parameters in the green box, but I have a question: In the drawing I see on the left side in the black arrow not a straight line but a kind of progressive curve. Therefore my doubt if the cart really follow a completely straight line or a kind of curve. Sorry for asking, but I am a bit slow in understanding it.

Best regards

Adelmo
 
Hi Adelmo,

Yes, in the beginning the name "linear tracking" is a little bit counterintuitive or misleading for this design.
You were probably expecting the stylus to have a straight line trajectory, the same as for the linear trackers using air bearings.
But here it's not the case. What matters is that, at any moment, the tonearm is tangent to the groove, so between the tonearm and the record spindle there are always 90 degrees (the green dotted lines in my drawing are showing this). The fact that the stylus is describing a curve along its path over the record has nothing to do with its "LINEAR TRACKING" ability. In this context, "linear" means "at all times tangent to the groove".
I hope my explanation makes it clear to you :)
 
Last edited:
Great! For security reasons all macro enabled Excel files are protected by default. You must first enable it.
How it works: In the sheet Drawing there are four cells highlighted in green. Those are the input parameters you can choose.
After that, clicking the button PLOT will draw the red curve representing the magnet guide path and the whole tonearm in several key positions, according to the selected input parameters.
Sometimes you can get a message box asking you to change some parameters. That's because the values chosen at that time yield a physically impossible structure (for example a sine or cosine >1).
Good luck!

Hi Consty,

Sorry to bother you so much these days. I went in the Drawing. chart, changed the figure in the green cells, click on th<e Plot, but nothing change.
Instead if I click on the green cells of the data, click the green v and input n<ew data the numb<ers are recalculated but nothing change in the drawing.
May be because this file is generated with Windows and I am using Mac?

Tks n rgds

Adelmo
 
Hi Consty,

Sorry to bother you so much these days. I went in the Drawing. chart, changed the figure in the green cells, click on th<e Plot, but nothing change.
Instead if I click on the green cells of the data, click the green v and input n<ew data the numb<ers are recalculated but nothing change in the drawing.
May be because this file is generated with Windows and I am using Mac?
Hi Adelmo,

No problem, I'm glad to be able to help you.
Unfortunately, I have zero experience with MACs. I only use Windows. You may still have some security feature blocking macro execution. Please read this link and see if it solves your problem: https://support.microsoft.com/en-us...4ce6-9b82-e02cbb85cb96#ID0EBBD=Newer_versions.
Also please note that I have purposefully linked the green cells in the Data sheet to the green ones on the Drawing sheet. This way the user doesn't have to switch between sheets for changing values and running the Plot macro. After you manually changed values in the green cells on the Data sheet, you overwritten the formula that was linking those cells to the ones in Drawing sheet. Keep this in mind!
If the solution given in the Microsoft link above doesn't solve your issue, the only other idea I have is to try and run the file on another laptop running Windows :)

Best regards,
Consty