Tone arm resonance and cartridge compliance: How do they interact??

Dear @cleeds  : Maybe @br3098 is refering that near the fulcrum makesthe tonearm has more operationsl stability but agree with you about modified the effective mass.

R.

The pickup arm works as a lever

Exactly. And the further mass is added away from the fulcrum the more destabilizing the effect. Resonance (the original topic of this post) is increased. A pivoted tonearm is not just a lever, it's a mechanical amplifier.

I'm not saying that adding mass to the headshell does not have benefit. But there are also detrimental effects. From the perspective of decreasing resonance and other artifacts the best of all worlds is to increase total mass uniformly and proportionally across the entire length tonearm and headshell. Barring that, adding weight to the tonearm closest to the fulcrum will have the most damping effect and reduce resonance frequency change.

If curious, this paper on Tonearm Mechanics does a pretty good derivation of the resonance and the effects of mass.
http://www.cartchunk.org/audiotopics/ToneArmMechanics.pdf  

It's essentially a problem in integral calculus.I have and will continue to align myself with what Raul and cleeds have said, which is what I also have written, in response to BR3098.  Adding mass at the headshell has the largest possible relative effect on effective mass, compared to adding mass anywhere closer to the fulcrum or pivot.  The effect of added mass on total effective mass is lessened as one approaches the pivot.  As we have already noted, adding mass, because it increases effective mass and would have the tendency to reduce the resonant frequency in magnitude, but not necessarily in amplitude, which would depend more on damping, stiffness, materials used, etc.

BR3098, forgive me for being overly sensitive and for misinterpreting your earlier remark.  In any case, I was not in any way upset or angry, just confused.

@lewm @cleeds 

Gents, my diatribes were only in regard to the OPs question regarding resonance. Obviously adding mass further out from the fulcrum is the most effective use of mass, but (as I described) is problematic for mechanical reasons and is not the most effective method of reducing resonance amplitude. Calculating the change in resonance magnitude will require additional information not provided.

Now if, as lewm proposed, we are allowing the alteration of other factors including "damping, stiffness, materials used" then all bets are off. I hadn't realized that we were discussing a tonearm with an infinite k value. 😁