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Geometry for pivot tonearms - calculation errors??

During several threads in Audiogon's Analog forum the question of pivot tonearm geometry was discussed widely and wildly the past weeks. There seems to be a great confusion about the interelation - and interaction - between overhang, offset, effective length, mounting distance and the position of the 2 zero-error points on the arc over the LP's grooved area.
However - the correct tonearm geometry is paramount for the performance of any analog sourced High-end system.

Do we need a new calculation of these parameters?
Is mounting distance a variable factor in a given pivot tonearms geometry?
Can overhang serve as the fixed parameter for a pivot tonearm?
Is effective length a variable or a fixed parameter in pivot tonearm geometry?
Is there anything like an optimum geometry for a given cartridge/pivot tonearm set-up?

I invite all interested in this complex and very important topic to contribute their thoughts. If possible please do include the geometrical derivation for any given theory and opinion.
This might be difficult in some examples, but please try.
By doing so, - this will keep this thread on terms and will make it more valueable for all.
dertonarm

Showing 2 responses by nandric

nandric's avatar
nandric
4,086 posts
 
Dear all, The separation in 'Tonearm Geometry' and 'Setup
Geometry' as proposed by our 'new authority' in tonearm
matter, Herr Dertonarm (sorry Raul) is the subject-matter
of one article in Audio,January 1980. The authors Kessler
and Pisha ware very suprised to discover that the most
Japanese tonearms producer got the 'arm geometry' wrong
(the 'beloved' FR-64 included). Suprised because the so
called ' optimal geometry' was know since,at least,1941.
The math. was my worst subject at school and I am realy
'annoyed' to be confronted with difficult 'formulae' in
my hobby. BTW the '1mm unit' is to me the smallest I can see and handle so I have no idea how to get my stylus 'spot
on' at 66,04 mm and 120,9 mm respectively.
Herr Dertonarm is 'threaten' us with the 'fractions' of
the 'unit' mentioned and call himself a Humanist. To me
he is a direct descendant of Frege (alias 'Perfectionist').
If we intend to get this 'perfect Geometry' in reality
then the chance to end in an psychitric instition is much
much larger then to get this 'TT-tonearm-stylus' conundrum
in correspondance with the 'demands' as stated by this
German perfectionist.

Regards and enjoy the music (if you can)
nandric's avatar
nandric
4,086 posts
 
Dear Dertonarm, My comparition with Frege was not
'accidental'. In intellectual or academic sence you can't
get a greater compliment. But even this 'greatest mind' of
Europe was 'destroyed' by his obsession with 'fundation of
math.';he never recovered from 'paradoxes' of ,say,set-
theory.
From Frege I learned not to treat 'disjunction' as 'entweder-oder' (or-or)proposition. So I am very puzzled with your statement:'Anyone NOT interested in
getting the tonearm/stylus geometry as close to perfection
as possible has a very good option: CD'.
Sorry Dertonarm but this statment is senseless to me.
Are you some kind of legislator?
I can assure you that I and others enjoy our 'imperfect'
TT-tonearm-stylys combos even if we know that thy are not
perfect. To me the quality of LP's (I own more then 3000)
is a much greater problem.
So don't get obsessed with 'theoretical matter'.
Regards,
Nandric
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