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How to change effective mass of a SME V.

I have a SME V. Its effective mass is quoted as 10-11. I wish to alter this to around 15-16. If I add mass to the headshell (and know how much) and crank the counterweight back how can I accurately re-calculate the ffective mass? The cartridge is 9.1 Gm, compliance 6. I know that the arm resonant frequency will change as well.

Regards Geoff
clarkie
quiddity
119 posts
 

BTW for a first approximation you can simply assume that the counterweight's contribution will be approximately 10% of the added headshell weight's.

If you wish to add say 5 g overall, you would add a headshell weight of about 4.5 g and expect the counterweight movement to get you (most of) the rest.

Mark Kelly
quiddity
119 posts
 

God I hate that I can't edit

The bracket is in the wrong place, the equation is

M . (Xa^2 - Xb^2) / Xel^2

Mark Kelly
nick_sr
263 posts
 
I don't want to beat a dead horse, but for good measure. After some careful consideration the calculation I proposed above is wrong.

It appears as though it could be okay in practice, at least with my technics tone-arm. That is when one pull the balance weight back by .5mm the tone arm move into a new inclined equilibrium.

In theory, this should not occur unless the pivot point is displaced to the new center of mass. I assume that the fact that in practice a new equilibrium point is found is due to friction in the pivot point and that the change of the center of mass is minimal.
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