How to measure tonearm effective mass

I couldn't resist the second link because of the stylus picture.

Since I put the link to the stylus, I should add that they look more like a rock instead of a nice looking gem(in 1st pic) for those that haven't seen one under a good microscope. This link shows a real one, if you scroll down about halfway. The second shows others, click on pic for close up. Sorry for going off subject.[http://www.bmpt1.com/][http://www.theanalogdept.com/cartridge_gallery.htm]

Damn this stupid forum software.

Can't edit anything. The above post makes no sense without the original VA post which is here: http://www.audioasylum.com/cgi/m.pl?forum=vinyl&n=677434

Mark Kelly

Lewm

Aren't you glad you asked ........

Chuck

Chuck, I AM glad that the question brought responses from some of the most knowledgeable people around this part of the hobby.
Viridian, The Catch-22 is the bit about needing a cartridge of "known" compliance. I guess one can figure that out by starting with another tonearm of "known" effective mass, or else one can start with manufacturer data, which I am not at all sure I trust. But thanks. As far as that goes, there was a neat idea from John Ellison on VA that is germaine to this issue. For a case where we know either the effective mass or the compliance of the cartridge, you simply drop the stylus onto an LP whilst recording the harmonic motion of the bouncing cantilever. For that he uses his computer and appropriate software. Once you freeze the decaying sine wave that describes the signal coming from the bouncing of the cantilever, you can make measurements that will get you back to the unknown parameter.
Mark, Did you make reference to the John Ellison method? I will take a look.