Tonearm Geometry and Setup


While this subject matter seems to be of 'crucial importance' for our hobby our discussion about this issue is fragmentary and split over different threads in our forum. As if we are talking about some 'abandoned child' that nobody wants. I thought that this 'child' needs its 'own home' in metaphorical sense or its own thread in the
usual sense. While tonearm geometry seems to be very 'simple' in mathematical sense there are many unresolved questions in the actual sence.
My question for the start of this thread is:
'why are we not free to choose the zero points on the record radius independant of the tonearm used?'

Regards,
128x128nandric
I got it. I have to do alignment/arm adjustment each time and somewhat differently before I play a record because they are all in one or more ways different. That's, of course, if I want the best results. And the better I can hear things the worse it is for me. Now that's a big fun and true joy.
Welcome to the audiophile madness club, everyone!
Dear John, If the designer is free to choose between Lofgren and non-Lofgren geometry than he obviously will do this according to his own preference or assumptions regarding the (potential) customer.But this way he already preselected the 'optimal adjustment' for the customer?
Kessler&Pisha stated in the context of 'Overhang' that many
Japanese designers 'overlooked' the dependance from or correlation with the eff. lenght. So, for exapmle, Dyna 505 has 15mm overhang while 17.164 should be optimal. Ie
the eff. lenght corresponding with 15mm overhang is 274mm
(10.787 in.). This lenght will not fit the turntables disigned for 9" tonearm ( Tonearm geometry and setup; Audio, January 1980). My 'intuition' is : you can't have
it both ways; the choice for the designer as well as the choice for the user. Ie the choice of the designer limits the choice of the user. As far as I know our choice for
Bearwald means the least distortion for the whole record
radius (aka 'avarage') while Stevenson means the least distortion near the lead out 'part'.
This means to me 'one way or the other' and this precludes
our 'free choice' or at least limits our choice. Otherwise
I am not able to make any sense of 'different tonearm geometry'.

Regards,


.
For those who think to be good in math but also think to
have good nerve there is an article from Stereophile by
Keith Howard on the net: ARC ANGELS; Optimizing Tonearm Geometry. Look for : tonearm geometry.
I myself should keep my promisse to myself made after
my high school : 'never ever mess with math '.

Regards,