12 inch Graham Phantom

>>10-04-10: Dertonarm
Seems that in high-end audio no statement is silly enough, that it don't become "proven statement" if it is only published somewhere online.<<

Amen

Each arm is optimized for a different standard. I would propose that it isn't a matter of 12 vs 10.5 vs 9 but more a matter of the individual arm and the setup geometry chosen. Lofgren A vs B vs Stevenson. The arcs they draw are extremely different. Also we need to take into account the different assumed inner Radii on the LP for calculating each arc. All of these add up to what we hear.

And if longer arms are better then why no 14 inches. We certainly have the materials to make the rigidity vs. length argument minimal and maintain a reduced effective mass.

Dgad, "why not 14 inches tonarms"? Because of the lack of available space on most turntables AND because the decrease in tangential error relatively becomes less and less with increased effective length.
14" and 16" tonearms were invented for and mounted on special broadcast turntables/plinth to be able to play transcription discs of large diameter common in the 1940ies and 1950ies.
On the better calculated 12" tonearms the maximum tangential error is already between 1.3° and 0.3°. This is a relatively large advantage to the 2.8° to 1.6° in 9" pivot tonearms. Lofgren A,B,C (vs in between...), Baerwald, Stevenson or any other calculation can be applied to 9", 10" or 12" effective length. It will not alter in any way the inherent advantage in tangential error (read: smaller...) of the longer version.
For those not to be convinced by physics and logic, there is always the opportunity to compare 9" to 12" versions of the very same tonearm.
Which leads us back to Graham and the 12" Phantom II.
Wider soundstage, more stable individual voices in complex choruses, more free and detailed high frequencies and a kind of "relaxed feel" in dynamic scale music.

I'm sorry , I can not see how an arm can be optimized for a particular alignment during the manufacturing process.
It can only rotates on it's pivot and we can choose to align the cartridge's stylus on whatever standard we wish, by simply rotate it's body and the pivot point.
Please tell me what I am missing?

"Also we need to take into account the different assumed inner Radii on the LP for calculating each arc".
I'm sorry I don't get it. What do you mean?
Of course the arm's pivot is different for each given standard but if we place the pointed edge of a pair of compasses at the pivot point & the other end at a point until the Eff. Length, then we can have the arc by simply rotate the compass against it's pivot.
I'm I wrong?

As for your question about why we don't have 14", maybe the answer hides on the easy money & cheap production cost of our times as I cannot find a logical answer.

George