Building a Tuthill/Reed 5A Tangential Tracking Pivot Tonearm

Bon,

If I understand it correctly, the arm you are talking about in #245 is on paper only. It is not doable because I don't see a guiding mechanism. For a Birch style arm, there are at least two links as my 6B. So, it is hard to discuss the pros and cons of the arm which is not doable. Once you have a geometry and it can be implemented, I will be glad to express my opinions.

Jim
Hi Jim.

I just posted on
https://www.diyaudio.com/community/threads/a-tangential-tracking-pivoting-tonearm.373127/page-11with some observations about skating. I don't know if it is relevant to your geometry, which is different to my model but related. It also more explicitly describes the guide mechanism. I am waiting on suitable CF parts to see if it is doable.

Regards

Bon
 
Doug,

I did the resonant frequency tests. Please see here. Both lateral and vertical resonant frequencies are 8-10 Hz. In my opinion, they are very good. I also tested the trackability of the arm. From the results, the cartridge and arm were doing very well. I compared the traces with the same tests on my air-bearing arms. They were very good even slightly better than my air-bearing arms. Here are my thoughts on primary listening.

I took the arm down now because I am modeling an attachment for my SME 20 table. Please see the image. The level adjustment is built in the attachment.

Screen Shot 2021-12-14 at 9.09.49 PM.png


The bass performance of 6B is on par with my air-bearing arms. I only tried Ortofon A90 on the 6B. Perhaps I should try other cartridges as well, especially, low compliance ones. I personally feel a medium compliance cartridge can perform excellently on my 6B. But the level of darkness is not as quiet as my air-bearing arms. The 6B arm takes a lot of space. Once it was installed, two of my air-bearing arms couldn't be played. This makes me hesitant to install the 6B permanently on the table.

Jim
 
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In my previous post, I designed 6C. Based on 6C, I came up with a new version, 6D. 6C has very small tracking errors, which are neglectable. And, 6D has even smaller tracking errors. The bearings for 6D are highly efficient. I think 6D is the best version of PT arms I have seen so far. I did a tracking error analysis. Here are the results.

Screen Shot 2022-01-06 at 10.54.32 AM.png


On 6D, all the goals have been achieved. It doesn't skate. Its tracking errors are neglectable. The tolerance of the arm may be larger than its tracking error. The structure is the simplest so far.

2022-01-06_19-25-39 (1).gif
 
I updated the 6D again. It is 6D MKII now.

I replaced the honeycomb 3D printed arm wand with an 18 mm in diameter and 2 mm wall carbon fiber tube. The honeycomb arm wand looks fancy but it may not do too much. I also replaced the aluminum guide with an 8 mm carbon fiber tube in order to reduce the possibility of noise.

Screen Shot 2022-02-20 at 11.26.04 AM.png


I still don't have any plan to actually make 6D MKII yet because I don't think the PT arm can outperform my air-bearing arms. One day, I may make 6D MKII just for fun.
 
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