The suspension of a cartridge can be modeled as a spring. The stiffness of the spring being the analog of the compliance of the cartridge suspension. The entire moving system has a primary resonance, or actually two primary resonances in the case of an arm using a decoupled counterweight. Think of the effective mass of the arm as being a weight on top of the spring, causing it to compress. The heavier the effective mass of the arm, the lower this resonance will be, the higher the compliance of the cartridge, the lower this resonance will be. When the arm resonance is excited, the arm rings like a bell, uncontrolled motion if you will, so the desire is to have a primary resonance away from things that excite it. Sonically, the implication is anything from muddy sound all the way to motorboating of the arm, with the cartridge losing groove contact, in the most extreme cases. On the low end, there is warp wow, in the six to ten cycle range. On the high end there is the actual bass recorded onto the record, twenty cycles. So we shoot for a primary resonance somewhere in the middle and even this is open to some debate. Since there is a range of acceptable resonant frequencies, there is usually quite a bit of leeway involved and most commonly used combinations fall well within the range that will not have audible consequences.
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