10 Inch Tonearms

@lewm Yeah, same table, same phono cables. Of course, the difference is relatively subtle, but it's there. Anyhow, the 12" looks so much better. 😉

@lewm No. But quickly swapped headshells. Same noted attributes follow the arms to different cartridges.

@goofyfoot 

I've seen Jelco arms on the used market, some of them 12 inch, some of them 10 inch and some of them 9 inch.

I have a 12" and a 9" Jelco 850 on my slate 401 and swap cartridges between them and can make on the fly comparisons. With that in mind, I can confirm that the 9" is faster and snappier while the 12" is not quite as fast but has a more expansive 3D soundstage and a tad more color which I find more musically satisfying.

As tablejockey said, 10" is a compromise —in a good way—giving some of the advantages of a longer arm with those of the 9". Legend has it that 9" is faster due to less mass, while 12" does the better tracking thang.