Uni-Protractor Set tonearm alignment

Dear Halcro: The FR64 manufacturer numbers are for Stevenson IEC geometry set up ( and Mr. Ikeda don't take the exact Stevenson parameters but only an aproximation: he put for example 15mm on overhang instead the calculated number: 14.91mm. he did the same for the offset angle and pivot to spindle distance. ).

With the FR 245mm efective length and 230.09 pivot to spindle distance the Stevenson IEC calculations gives you: 0.728 on maximum distortion with 0.477 as average distortion.

If you change the pivot to spindle distance to 231.5 then the new Stevenson IEC calculations gives you: 246.324mm EL with 14.824 on overhang and maximum distortion is 0.724 an average one is 0.474.
Changing only the overhang to 14.5mm gives you a maximum distortion 0.724 with an average of 0.475.

Now for each one of this calculations the offset angle is different. The FR manufacturer offset number is 21.5° that's is greater than the 21.149° and 21.269° on those calculations.
So, if you don't change the 21.5° original/manufacturer cartridge offset angle then what you have is higher distortion levels that the ones here calculations showed.

If all this is true IMHO that you like better a higher distortions set up is not at all something weird, all the time some of us like some kind of higher distortions than lower ones.

I don't have mounted my FR right now ( its borrowed to some one that want it. ) so I can't make tests for my self.

Please do it a favor and change that near Stevenson IEC set up for Löfgren A/Baerwald as follows:

overhang 16.8mm, offset angle 22.4° and pivot to spindle distance 228.2

please test this set up and compare against the one you are using and appreciate you comeback with your comments.

Thank you in advance.

regards and enjoy the music,
raul.

Halcro, of course that you have to re-set the VTA/SRA and Azymuth for the new geometry set up. Sorry to take your time but things could be that you could like the Löfgren/Baerwald geometry. We don't know yet.

regards and enjoy the music,
Raul.

Halcro: you said that you was using 230mm pivot to spindle on Baerwald and this is for a 246.736mm on EL that is diffferent from the 245mm manufacturer number and that gives you different overhang and offset angle.

Anyway if we/you want to compare the same 246.324mm EL as with Stevenson ( at 231.5 pivot to spindle. ) then on Baerwald the overhang is 16.76mm with an offset angle 22.29°.

Regards and enjoy the music,
raul.

Btw, the maximum distortion on Baerwald is 0.598 with an average one 0.390. These figures are lower than the Stevenson ones you are using by around 23% lower.

Regards and enjoy the music,
raul.

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.