Dear Halcro, the change to 231.5 mm mounting distance (and thus effective length, offset(slightly) and overhang does indeed result is a lower overall distortion level for about 74% of the grooved area compared to the "original" specification in the FR-60 manual/paper template of the FR-64s.
Distortion levels at the start of a 12" record are far less obvious (read: audible) and far less dangerous then they are towards the inner label.
Why so?
Because the difference in radius of the inner groove wall towards the outer groove wall increases with decreasing record radius.
Not a great situation for the stereo stylus.
This too is one of the reasons, why "average distortion" and "maximum distortion" figures for a given tonearm alignment calculation only give half the story.
Where are the maximum distortions? At the start of a record (usually with my calculations) or at the end of the grooved area (Löfgren A/Baerwald and Löfgren B).
How is the "average" determined ? By a narrow but very high maxima and a long area with low distortions ? Or by a rather long area with mid distortion level but no real high peak ?
IMHO (god - I really begin to love this phrase ... ) average and maximum distortion figures may be fine and all for some, but they do not really get to the core.
So why did you hear immediately an improvement in sound with "my" recommendation changing the FR-64s alignment?
First - you had less skating force (remember me saying that there might be additional breakdown torque with an added offset?).
Second - the not linear distortion level was less by 30% for more than 70% of the record.
Third - the FR-64s' "inner" geometry was finally matched by that alignment.
Some may think it is all just effective length and the resulting and depending parameters - offset and overhang.
IMHO ...;-) .... - that is not the complete entire model and doesn't tell all the story.
BTW - all UNI-Protractors of the 1st production run do get collected for ship off tomorrow and thursday.
Cheers,
D.
