Tonight I had a chance to go poking around on Vinyl Engine for more info on these two tonearms,
(1) It appears that Nicola may be correct; the "N" may stand for "NEW". On VE, there is a reprint of the brochure for 308NEW.
(2) The 308SX is shown with the ceramic headshell; the 308N does not have the ceramic headshell. So that was one difference. The SX version has larger heavier "ears" flanking the bearing housing, to increase lateral effective mass. The arm tube of the SX might or might not be different from the N.
(3) The P2S distance for the N and probably for the SX is given as 235mm. Only 5mm of stylus overhang is recommended, for an effective length of 240mm. With a headshell offset angle of only 12 degrees, this results in an inner null point of 39.2mm (!) and an outer null point of 60.6mm. The ad copy says no tracing distortion on innermost grooves. I can believe that, since at 39.2mm from the spindle, the stylus is at best reaching the run-out grooves if not only the outer edge of the label. At 60.6mm it would probably be within the innermost cut of the LP. So they compromised the tracking angle over the whole rest of the LP in order to minimize tracking angle error in the innermost grooves. In contrast, Stevenson results in null points at ~60mm and ~117mm. And Baerwald and Lofgren B both have their null points farther away from the spindle than Stevenson. So the SAEC geometry is strange, indeed. Why choose to set your tonearm up so that only one null point occurs where there is music? Dunno. For one thing, the small headshell offset angle would tend to reduce skating force.
(1) It appears that Nicola may be correct; the "N" may stand for "NEW". On VE, there is a reprint of the brochure for 308NEW.
(2) The 308SX is shown with the ceramic headshell; the 308N does not have the ceramic headshell. So that was one difference. The SX version has larger heavier "ears" flanking the bearing housing, to increase lateral effective mass. The arm tube of the SX might or might not be different from the N.
(3) The P2S distance for the N and probably for the SX is given as 235mm. Only 5mm of stylus overhang is recommended, for an effective length of 240mm. With a headshell offset angle of only 12 degrees, this results in an inner null point of 39.2mm (!) and an outer null point of 60.6mm. The ad copy says no tracing distortion on innermost grooves. I can believe that, since at 39.2mm from the spindle, the stylus is at best reaching the run-out grooves if not only the outer edge of the label. At 60.6mm it would probably be within the innermost cut of the LP. So they compromised the tracking angle over the whole rest of the LP in order to minimize tracking angle error in the innermost grooves. In contrast, Stevenson results in null points at ~60mm and ~117mm. And Baerwald and Lofgren B both have their null points farther away from the spindle than Stevenson. So the SAEC geometry is strange, indeed. Why choose to set your tonearm up so that only one null point occurs where there is music? Dunno. For one thing, the small headshell offset angle would tend to reduce skating force.