I am going to have to get an education on all this and appreciate all the helpful information I am finding around here. What a great site you guys and gals have going here. Thanks
Too many people think the resonance frequency needs to be exactly one frequency be it 7, 8 or 9 Hz. Here is something to keep in mind when evaluating whether a cartridge compliance/tonearm mass will work well.
The resonant frequency is the frequency that the cartridge/stylus gets excited based on the mass of the system holding it and the compliance of the stylus assembly. The calculator on VE gives you the whole number but the fractions are missing. That doesn't matter. The whole number should be enough because what you are trying to do getting the right number is avoid the record warp frequencies 0-4Hz and the low bass on a record frequencies 16Hz and up.
Let's talk record warp, for different bumps per revolution you are looking at the very low frequencies, 0-3Hz, I'd say. You do not want a cartridge resonance in that area as the excitement from the low frequencies added by the record warp will make a 'Galloping Gertie' out of the arm/cartridge and the nail will jump out of the groove. Galloping Gertie is the Tacoma Narrows bridge that wind blew at the right speed to excite the resonance frequency of the bridge causing its collapse just a few months after construction was completed. Resonance at the wrong frequency can be bad.
So we are avoiding anything down low. Now the other end.
Records have sound recordings on them with a frequency response of generally 30-20kHz or much higher for Quad records of 50kHz max. Some records will have lower frequencies for deep pipe organ or special records and such. So we want to avoid a cartridge/arm resonance frequency of anything close to 20Hz on the top end.
This leaves us with a useable range...with the center of that range in the 7.5-9.5 area. That is ideal but it does not mean you will suffer if your resonant frequency is 5 or 12-13. Folks get too concerned with making that hand grenade land exactly on the target when anything within a few yards will do a fine job of the removal of the problem.
So if your work to determine resonance gives you a result of 13, roll with it, no reason to add weight that may cause other problems when the 13Hz will not. If you experience a problem then consider a heavier mounting system, big thumbscrews maybe. With many arms the choice of headshell can make differences that will help but some fixed mountings are not so versatile.
Best cartridge/arm combo I have heard here is an Ortofon MC30 Super on a Fidelity Research FR-64s, somewhere in the mid-6Hz range. Wonderful, kept me reaching for more vinyl to play early into the morning.