Angling for 90° - tangential pivot tonearms

tade · 2011-10-22 11:12 pm

Ohhh now I remembered why I abandoned the pivoting headshell idea.

With linkages you get a parallelogram type of system. The two lines will stay parallel, and the cartridge will maintain its angle relative to the platter, but the parallel linkages will change their distance and still trace an arc across the record. This arc will change the angle at which the groove is read, and thus, the angle it sits in the groove. I don't think this system can be any better than a traditionally set up arm with perhaps an offset headshell.

directdriver · 2011-10-23 5:07 am

tade: "The two lines will stay parallel, and the cartridge will maintain its angle relative to the platter, but the parallel linkages will change their distance and still trace an arc across the record. This arc will change the angle at which the groove is read, and thus, the angle it sits in the groove. I don't think this system can be any better than a traditionally set up arm with perhaps an offset headshell."

What I proposed is NOT a parallelogram approach. It is, in fact, a tetragon system that is based on the Thales theorem. Check the Thales Simplicity tonearm page for further reading. In fact, this entire thread is based on the Thales theorem, hence the title "angling for 90° - tangential pivot tonearms."

The two sides are NOT parallel. The guiding rod is to keep changing the angle of the stylus at the headshell to conform to the Thales semi-circle for tangency or at least close to tangency. It does not approach perfect tangency like the Thales tonearm but it will be closer to the Garrard Zero 100 or Thales Simplicity. Tracking error will be much lower than traditional headshell with offset angle. Of course, complication in construction and extra pivot bearings will deduct some of its performance. You gain a little, you lose a little...

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stevieg · 2011-10-26 6:24 pm

Think of it as a linkage or an extremely short string between two rigid parts or think of the Schroder arm with a very very short string.

With you. This is to avoid bearing rattle and alignment issues. Not an ideal solution, but as the engineer said about bicycle derailleur gears - "it's brutal but it works!"

This is pretty much my favourite thread here.

phivates · 2011-10-26 11:30 pm

I must agree. Why no stars?

directdriver · 2011-10-27 5:31 am

"articulated arm"

stevieg: "This is pretty much my favourite thread here."
phivates: "I must agree. Why no stars?"

Thank you for the kind words! Star or no star, doesn't matter. Besides, I haven't built anything that I posted on here so I am not worthy. All I can provide is some entertainment. Glad you enjoy it.

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Speaking of entertainment, I found more goodies. Another patent on "articulated arm."

Patent 3963246, filed 1975 by inventor Jaroslav George Trochimowski

An externally hosted image should be here but it was not working when we last tested it.

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directdriver · 2011-10-27 3:10 pm

more patented ideas

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Another patent! This one is closer to the Garrard Zero 100 concept.

This one is from Patent 3502339, filed on 27-Jun-1968 by E.O.P. Tatter et al. Total 8 pages. Below are first 4 pages including some pictures and introduction.

An externally hosted image should be here but it was not working when we last tested it.

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directdriver · 2011-10-27 3:24 pm

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Patent # 2455529 from 1946 by Hubert L. Shortt.

An externally hosted image should be here but it was not working when we last tested it.

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directdriver · 2011-10-27 3:43 pm

Here's an interesting one:

Patent # 2522997 from 1944 by A. E. Coppleman.

An externally hosted image should be here but it was not working when we last tested it.

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directdriver · 2011-10-27 3:55 pm

Patent # 2966360 from 1957 by Macel Herve.

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directdriver · 2011-10-27 4:26 pm

US Patent # 3051493 from 1962 by R. C. Dreier.

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directdriver · 2011-10-27 4:29 pm

All of the above patents are referenced by the resourceful Canadian inventor Jaroslav George Trochimowski in patent # 3963246 from the below paragraph.

"In order to reduce the tracking error and skating of such conventional tone arms, numerous attempts have been made to ensure that the stylus lies tangentially to a circle centered at the center of the record and thereby vibrates in a radial direction. Suggested solutions can be seen, for example, in U.S. Patent Numbers:

2522997 of Coppleman
2966360 of Herve
3232625 of Van Eps
3826505 of Birch
2455529 of Shortt
2983517 of Klein
3051493 of Dreier
3502339 of Tatter et al
*582660 of Burne-Jones (*Canadian Patent Number).

Many of these solutions proposed are cumbersome and expensive to incorporate on a record player. Most of these solutions which suggest articulated tone arms require several pivot points at which frictional forces can be exerted upon the tone arm to reduce its efficiency. These pivot points and sources of friction are necessitated by the very nature of the geometrical solutions to the tracking error and skating problems offered in these prior art solutions."

So, what do you think of HIS invention?

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directdriver · 2011-10-28 6:24 am

Van Eps Lab Tonearm

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For sheer cool factor, nothing beats the Van Eps tonearm!

Found some bigger size files and some pictures are new images never posted before.

An externally hosted image should be here but it was not working when we last tested it.

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RCruz · 2011-10-28 3:55 pm

It must be a pain just to set VTF on that contraption.

walterwalter · 2011-10-28 8:42 pm

To RCruz. We, vinyl audiophiles aren't looking for the easy ways of playing music. Lazy people went digital long ago

directdriver · 2011-10-28 8:53 pm

RCruz: "It must be a pain just to set VTF on that contraption."

I think so. You can try placing Blu-Tack on the headshell and then add or remove to the right amount for tracking force. Cheesy but, maybe, less painful. Aren't audiophiles masochists?

It certainly makes that string tonearm look easy to use.

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directdriver · 2011-10-29 12:10 am

"Evolutionary Optimization of a Novel Tonearm (2006)"

Just found another attempt at tangency! This one is similar to the Garrard Zero 100. Check it out!

This comes from a Slovakian inventor Marek Bundzel, Ph.D. with an impressive resume.

You can download his whitepaper and graphics here on zip files.

In one of the graphs, the set up can reach a maximum deviation of 0.052° and can be as low as 0.009°! Not quite as low as Thales Simplicity's 0.008° but still very impressive.

The author says:

"This is a set of Matlab scripts running evolutionary optimization of the parameters of a high end tonearm of a novel design. The purpose of the design is to maintain the needle in the optimal angle with the grooves on the record (tangent).

run.m is the script to start with. I appologize for the very poor documentation. This folder contains images of the solutions found. This software is free. The author may not be held responsible for anything regarding this software . "

Too bad I can't find bigger and more detailed pictures of this interesting design.

An externally hosted image should be here but it was not working when we last tested it.

directdriver · 2011-10-29 5:50 am

If you're not tired of seeing the Thales tonearms yet...this website shows the manufacturer came out with a Thales turntable that can hold two tonearms.

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directdriver · 2011-11-05 3:02 pm

more patented designs

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This one is a split-plane design a la Dynavector with additional pivot and it also reminds me of a design by Mark Kelly from post #34.

US Patent number: 4346466

Inventors: Kanchev; Peter K.
Filed: 31-May-1979

An externally hosted image should be here but it was not working when we last tested it.

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tade · 2011-11-05 5:55 pm

oh why oh why don't they use a radial arm to cut records!!!!???

Nanook · 2011-11-05 6:25 pm

floored by the mass...

One thing that bothers me about multiple linkage arms (Thales, Garrard, whatever....) is the relative disregard for the moving mass and the sprung and unsprung mass of the arm/cartridge system. This is in comparison to the much (potentially) lower mass of much simpler arms.

This is not an indictment of the multiple linkage arms, no defense is needed, but is just a comment. So owners of the Thales (and others), DIY multiple linkage types or the Garrard (which I have) need not comment other than on the mass. The Thales arm looks to be very well engineered and beautifully finished. And I am sure (based on reviews etc,) that they sound excellent.

Angling for 90° - tangential pivot tonearms

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