The arm Marco uses is the Ortofon AS-212S : http://www.ortofon.com/products/hist...ducts/as-212s; a now discontinued product.

From the above link it can be seen the arm has an effective length of 231mm, with an offset angle of 22° and overhang of 15mm. The recommended radial null points are 58.5mm and 114.5mm.

Curiously this geometry corresponds to neither Baerwald, Löfgren nor to that of Stevenson. Using the equations quoted in http://theartofsound.net/forum/showt...earm-alignment, we can calculate the following: -

For Baerwald (IEC) geometry: offset angle = 23.86°, overhang = 17.97mm and the radial null points are at 66.0 and 120.9mm,

for Baerwald (DIN) geometry: offset angle = 23.28°, overhang = 16.31mm and the radial null points are at 63.1 and 119.2mm.


For Löfgren (IEC) geometry: offset angle = 23.86°, the overhang = 18.48mm and the radial null points are at 70.3 and 116.6mm,

for Löfgren (DIN) geometry: offset angle = 23.28°, the overhang = 17.42mm and the radial null points are at 67.4 and 114.9mm.


And finally for Stevenson: the offset angle is 22.57°, the overhang = 15.8mm and the null points are at 60.33mm and 117.0mm.

Comparing the latter figures with those quoted by the manufacturer, it can be seen that the arm geometry is closest to that of Stevenson. The manufacturer’s recommended null points are correct given the arm geometry, but do not correspond to the Baerwald values as used on most alignment protractors.

So whilst it would seem Ortofon have chosen their own geometry, the arm/cartridge alignment will be optimised if their recommended null points are used.