Interspace arm Length

It's meant to be a vertical pivot-to-stylus length, so are there two sets of headshell mounting holes 12 mm apart? or some way to slide the cartridge back and forth up to 12mm to adjust the overhang? I don't know much about that arm, but it sounds like an adjustment range. If this doesn't sound right, you should contact them -- it doesn't seem like a typo ;--)

Nsgarch: The headshell is set up to slide the cartridge -- but the sliding track is not 10mm. The different lengths appear in the dealer's manual first on the specs page for all nottingham arms and then on the paper protractor provided.

Then I would definitely contact them to explain the discrepancy. It's possible, as often happens, that they made a slight design mod. between the two printings. Wish I could be of more help.

You want to derive the pivot to STYLUS distance which is the tonearm's effective length.

My guess is that the numbers you are quoting are the pivot to SPINDLE distance which is a smaller number - smaller by the amount of overhang.

In terms of real-world numbers (e.g. a Rega tonearm), a 239mm effective length (pivot to stylus) will yield a 222mm pivot to spindle distance.

The shorter 9" tonearms are in the 211mm range for pivot to spindle.

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For our purposes, you can derive the stylus position as being a point that's 10mm ahead of the cartridge mounting bolts (nominal specification).

So, find the midpoint of the two cartridge mounting slots and draw an imaginary line connecting them.

From the midpoint of this line, draw another one (parallel to the cartridge mounting slots) that's 10 mm long.

This is where your average stylus would be positioned if you mounted your cartridge in the middle of the headshell slots.

Now, measure the straight-line distance from this point to the center of your arm's bearing.

This is your pivot to STYLUS distance which is referred to as EFFECTIVE LENGTH.

Run this number through John Ellison's way-cool Baerwaald / Lofgren spreadsheet (available throuth the Enjoy the music website - or ... a link on my support page). You'll get both the overhang (and by inference the pivot to spindle distance), as well as the headshell offset angle.

Cheers,
Thom @ Galibier