[drmoss_ca]

I've never been one to pay a lot of attention to tonearm resonant frequency, and maybe I've just been lucky that it hasn't been a problem. But now I find myself discovering something that is interesting to me, even if obvious to everyone else! I have a Benz Micro LP-S arriving in a couple of days, and it's a heavy cartridge. I was going to put it on a Rega RB330 tonearm, and knowing the problems I had balancing a lighter cartridge on my other RB330, I ordered a second Groovetracer counterweight. In the meantime, my plans changed a bit, as the newly re-tipped Kontrapunkt C on that RB330 has been entrancing me, so I decided it would stay there, and the LP-S will go on an SME Series IV instead. But the Groovetracer was on the way, so when it arrived today, I installed it with the 150g weight (the standard RB330 counterweight is a hair under 100g). I balanced the arm and cartridge with VTF and anti-skate set to zero, then reset VTF to the recommended 2.5g and added back the anti-skate. According to a resonance calculator, this has reduced my resonant frequency from ~8.7Hz to just above 8Hz. It says 10Hz is ideal. But I don't know exactly what the new effective mass is of this tonearm is now, so that's a bit of a guess. The thing is (and I'm as susceptible to psychoacoustics as the next guy), I think it sounds better with the larger counterweight! I'd say fuller bass, but still tight and controlled rather than loose or excessive.
Am I nuts?

[Letitroll98]

The lower the resonant frequency the better, until it runs into record warp frequencies, usually 4-6hz.  So experts guesstimate 10hz or so as low enough below human hearing and high enough above warp frequency to be safest.  But you can go below 10hz with no issues, obviously as you've experienced.  As for improved bass by going .5hz lower I just don't know, but it could happen I suppose.

[drmoss_ca]

I don't know if resonant frequency is the best metric for describing what happened. I'm thinking in very basic terms: an arm with higher effective mass will have more inertia, and thus require the cantilever to move more (as the arm moves less) in response to the same groove deviations. Resonant frequency reflects that change but can't explain it all, after all, if the cantilever has to move more, wouldn't that increase the amplitude of the signal, and the resulting volume?