A quick note on arm/cartridge resonant frequencies:
When the mass of the arm (as seen by the cartridge at the headshell) reacts to the springiness of the cantilever, there is a low frequency resonance. This can give rise to vertical, horizontal and, in the case of unipivots, rotational (about the armtube axis) oscillations.
This of itself is not necessarily problematic. Much depends on the amount of energy that is in the system. If the resonant frequency is within a low energy range of frequencies, it is unlikely to be excited. Generally this means a frequency below the lowest audio signal either on the record or in the air, and above the highest frequency transmitted through the turntable suspension or support.
Record warps range from 0.5Hz to approximately 8Hz, depending on their nature, and, depending on arm design, mainly affect vertical resonances, while record eccentricity affects the horizontal.
Generally, record warps are the most obvious problem source if an arm cartridge combo has an excessively low resonant frequency, easily seen in excessive woofer movement, but also most easily sorted - through not playing warped records, or using some form of clamp to reduce the amplitude of the warp.
Generally, record warps are the most obvious problem source if an arm cartridge combo has an excessively low resonant frequency, easily seen in excessive woofer movement, but also most easily sorted - through not playing warped records, or using some form of clamp to reduce the amplitude of the warp.
More subtle are resonances induced by low amplitude ripples on the record surface, suspension harmonics or large bass signals, which can affect bass response and imaging, especially with some unipivots.
The three resonant modes are not necesarily the same. The horizontal usually being the lowest, although with unipivots the rotational mode frequency will depend on the distribution of mass about the pivot. Also the resonance characteristics will be more or less peaky depending on arm features and design, which affect how resonances are damped.
The turntable design is also important. If it is a sprung suspension design, then it has its own built-in isolation from structure borne vibration. If it is a solid plinth design, then it is prone to transmitting vibration from its support unless mounted on an isolation platform or other form of energy absorber (which effectively turns it into a sprung suspension design). Cones are principally stability devices and transfer vibration in both directions.
