Tonearm Geometry Analysis by Graeme Dennes (c) 1983,2018

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Tonearm Geometry Analysis by Graeme Dennes (c) 1983,2018

Post by JaS » 19 Oct 2005 06:38

The 2008 document has been expanded with added sections, added formulae, added derivations, and numerous enhancements within the material, and is now more comprehensive than before. Further emphasis has been placed on the facts, both in the introductory section and the added sections. A number of minor corrections has also been made.

Updated February 2009, June 2010, February 2011, October 2013, March/September 2015, August 2018

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Many thanks to Graeme F Dennes for the paper

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Post by JaS » 08 Jan 2008 12:10

updated

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Post by JaS » 08 Feb 2008 11:55

updated feb 2008

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Post by JaS » 02 Mar 2009 14:42

updated feb 2009

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Post by JaS » 09 Jun 2010 20:49

Updated June 2010

Thanks again to Graeme F Dennes for allowing us to share this paper

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Tonearm Geometry Analysis Paper - June 2010 Revision

Post by Graeme Dennes » 14 Jun 2010 09:31

(Author's Note):

The paper now contains 217 pages. Overall, a significant revision, with much new material, as follows:

1. The complete derivation of eighteen of Löfgren's equations underpinning the 'Löfgren A' and 'Löfgren B' alignments is provided, including the familiar optimum offset angle and overhang equations.
2. The tracking distortion pages have been greatly expanded to include the theory and practice of tracking distortion and RMS distortion calculations.
3. The RMS distortion equation, which forms the basis of the 'Löfgren B' alignment, is derived, as well as the null radii equations (provided first by Baerwald).
4. The complete details of the spreadsheet data and calculations needed to determine RMS distortion is provided.
5. The spreadsheet settings for calculating the high accuracy (ie, "perfect") 'Löfgren A', 'Löfgren B' and 'Stevenson A' alignment settings are included.
6. From the time I became familiar with Baerwald’s paper, a number of questions have arisen. These questions and the background to them are discussed in Section 1.

Thanks to everyone for their continued interest in this document.

Graeme Dennes

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Post by JaS » 25 Jun 2010 09:38

updated

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Post by m2003br » 14 Nov 2010 23:00

Thanks, Mr. Dennes, for share this great paper!

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Post by Graeme Dennes » 19 Nov 2010 13:11

Thank you for your kind words. I'm pleased to know the paper is of benefit to you.

Apologies for the late response.

All the best.

Graeme Dennes

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Re: Tonearm Geometry Analysis by Graeme Dennes (c) 1983,2010

Post by gconder » 25 Jan 2011 16:25

Dear Graeme

Great work

One question
in 1-16 Beta=21.94... for Loegfren A
in 1-20 Beta 20.82... for Stvenson A

Why do you say in 8-2 OPTIMUN OFFSET ANGLE that e. Stevenson as Loegfrens??

Can you pls clarify?

Regards

Guillermo Conde

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Post by Graeme Dennes » 27 Feb 2011 15:30

Thank you for your question.

As background, the purpose of Section 8 is to summarise the alignment equations provided by the six authors for achieving the three-point, equal-weighted tracking error alignment (which I termed the 'Löfgren A' alignment). Also, the overall thrust of the original (1983) document was in regard to the 'Löfgren A' alignment, which was the common thread running through the six papers analysed. The table on page 8-1 compares the optimum offset angle and overhang equations by the six authors for the 'Löfgren A' alignment.

On page 8-2 are listed the optimum offset angle equations by the six authors for the 'Löfgren A' alignment. For Stevenson's 'Löfgren A' offset angle equation, it states, as you've noted:

e. Stevenson: As Löfgren's

It should have stated:

e. Stevenson's 'Stevenson B': As Löfgren's

This would have prevented the confusion you've experienced, because the 'Stevenson B' alignment is identical to the 'Löfgren A' alignment, whereas the 'Stevenson A' alignment is different.

Similarly, Stevenson's 'Löfgren A' overhang equations on page 8-5 should also have read as:

f. Stevenson's 'Stevenson B': (equations as shown)

I'll revise those words in the document. Thank you for bringing this to my attention, and I do apologise for the oversight, and the confusion.

Sorry for the late response to your question.

Graeme Dennes

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Post by JaS » 27 Feb 2011 19:52

updated

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Post by JaS » 28 Feb 2011 07:49

updated

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Re: Tonearm Geometry Analysis by Graeme Dennes (c) 1983,2011

Post by JaS » 11 Oct 2013 17:58

Updated October 2013

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Re: Tonearm Geometry Analysis by Graeme Dennes (c) 1983,2013

Post by safesphere » 20 Feb 2015 07:46

Thank you for an informative paper. One thing to correct is that the linear offset in Loefgren's work is given for the "Loefgren A" method and is only approximate for "Loefgren B". He minimizes the distortion integral by effectively varying the overhang, but skips varying by the linear offset thus keeping it only approximate.

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