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

The beauty of the adjustable-mass counterweight of the Zeta arm (accomplished via removable steel discs in the hollow counterweight) is that if one wants to use the arm in it's lowest effective mass guise, more discs are placed in the counterweight and that cw is placed as close as possible to the arm's bearings. For higher em, fewer discs and the cw further away. Counter-intuitive, but true.

My Triplanar and I suppose several other tonearms achieve the same end by supplying a set of CWs that vary in mass. You can slide them on or off the rear end of the arm. Further the Triplanar CW is physically decoupled from the pivot by a nonrigid damped joint.

Dear @lewm : obviously that a tonearm as a cartridge in static way has no intrinsec resonances but in the very first moment that the TT spins even with the tonearm in rest that tonearms has " resonances/vibrations " at micro levels. So @bdp24 is rigth about.

The overall subject always been a little controversial because the formula calculates the resonance frequency of a cartridge/tonearm at static/rest way. The numbers are the ones from those combinations of tonearm-cartridge and it’s a good place to start with the subject but those numbers will change during playback because exist additional parameters that affects it.

Yes, the formula says what you posted but you have experiences where that not really happens during playback because you love that very heavy FR tonearm with a cartridge boarding in the 40-50 cu and you love that combination.

So, some one out there needs to model what in reality happens taking in count all those multiple factors/parameters around this controversial subject.

Even those always is convenient try to achieve the ideal frequency range in our tonearm/cartridge combinations because the quality performance will be better than if we don’t care about. Problem is that several times we like what is wrong and dislike what is rigth !

Btw, """ supplying a set of CWs that vary in mass . "" this was posted too by @bdp24 with his Zeta tonearm but is not critical inside the resonance formula because the CW is near the fulcrum and contributes very low for the total mass.
What is important for place/position the CW the nearest we can to the tonearm bearing is to gives to the tonearm a better overall " displacement/operation " during playback, give an additional facility to the tonearm work.


Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

Dear Raul, I have to differ with you only on what you wrote in your first paragraph. The effective mass of the tonearm and the compliance of the cartridge determine the resonant frequency according to the formula that you know and I know too. You are probably right that in the real world resonance  is not so easy to figure out just from numbers. The first of all problem is that we really usually don’t know the effective mass of the tonearm/cartridge we’re using. For example, the Fidelity research has a very high effective mass when used with its factory supplied head shell, which in itself is heavy. And head shells have an inordinate affect on effective mass, because they are out there at the end of the tonearm. I use the Fidelity research tonearm with a high compliance cartridge, but I use a very lightweight head shell when I do that. And yes, from a listener standpoint the combination is very successful. But I have to freely admit that I really don’t know exactly what is the effective mass of the tone arm and cartridge combination that I ended up with. The Acutex cartridge that I used with the Fidelity research tonearm is also an extremely lightweight cartridge body in and of itself. Probably many grams lighter than a typical fidelity research cartridge of the vintage era. I can only tell you there is no audible sense that the resonant  frequency is interfering with bass response or anything else. The best way to work out what is going on with the tonearm and cartridge and resonance  is probably to figure out the resonant frequency by using a test LP or a very novel test that I read about on vinyl asylum. So then you would hopefully know the compliance of the cartridge and the resonant frequency and from that you can work backwards to get some idea of effective mass.