Micro seiki Ma-505lx

Try Vinyl Engine. They have copies of manuals available and other resources available to get the information you are seeking.

http://www.vinylengine.com/library/micro-seiki/ma-505.shtml

I could be wrong, but I don't think Micro Seiki provided effective mass specs for any of their tonearms.

MA-505xl? Is that the 12 inch version? I don't know what its effective mass is but it is a heavy arm. I used to own a 505s which was a 9 inch arm with silver wire. When I was making the purchasing decision, I was debating whether to get the 9" or the 12". I remember I auditioned the 12" arm with an EMT cart tracking at 3g! It is a heavy arm. Don't try anything with high compliance on it.

yes, it's the 12" version. Nothing to find in vinylengine either.

You might want to pose your question in the Yahoo forum:
http://groups.yahoo.com/group/MicroSeiki/

Another Micro Seiki resource:
http://my-micro.de/micro_home_gb.htm

Thanks, for the links. Still thinking consithering the stabilizer, but I think it's too expensive without knowing if it will do any good...