For a rather comprehensive treatment of the Audible effects of resonance, the B&K article is excellent:viewtopic.php?f=46&t=1281
From which article the following quote (page 5):
The physical meaning of a resonance is increased amplitude of the relative movements between the record surface and cartridge and, in addition, the lower the frequency the greater the amplitude. Therefore all the time the cartridge wil oscillate at the tonearm resonance with large excursions - just the prescription for making intermodulation distortion on tones in the audible band.
I would also refer you to the test plots (page 9) showing the intermodulation sidebands on a 3kHz tone for three setups, undamped 7Hz resonance, undamped 9.5Hz resonance and damped 16Hz resonance.
The best result, with the least additional distortion is the damped 16Hz setup.
From a conclusion paragraph on page 9:
From this it is clear to see that to improve audible quality the main problem is to reduce the relative movements between cartridge and record as much as possible. In other words, one has to damp the arm resonance and move it upwards in frequency.
Note that this only focuses on distortion / IMD sidebands - it is not looking at the impact on the bass of having the resonance too close to the lowest audio frequencies. If the resonance is undamped and get up over 12Hz it will start to impact/boost the lowest frequencies... 18Hz is the frequency of the lowest / biggest pipe organ pipe. - so raising the res f higher may impact of the low end performance (by boosting it)
Lots more good info in that article!
Another good article for information on resonances, stylus scrubbing (the motion that causes the intermodulation discussed above) and other parameters of performance is the Shure Technical Seminar:http://shure.custhelp.com/app/answers/d ... aWhZbGs%3D
bye for now