I wouldn't take a little Internet "buzz" or speculation based on the tonearm mass/compliance formula to rule out the Ortofon 2M Black. At the very least, talk to somebody at Needle Doctor or Acoustic Sounds. I believe there are several online vendors that sell both Ortofon and Rega products.
10 Hz may be the ideal resonant frequency, but the tonearm database matching grid seems to indicate that anything from 8 to 11 Hz or so is ideal. The 2M Black on an RB300 comes in at about 8 Hz.
And another thing: The formula may be able to give you the resonant frequency, but it can't tell you how strong the resonant frequency is, because that depends on other factors such as tonearm design and damping. I'm not sure how vulnerable the RB300 is to mass/compliance resonances.
There are certainly some designs that can dampen most of the resonance back down. For example, a cartridge's damper brush (such as is on the Shure M97xE and was on the V15 series) reduces the resonant hump by around 5 dB. Ditto for tonearms with fluid dampers. I'd rather have a 0 to 1dB resonant hump at 8 Hz than a 5dB hump at 10 Hz.
10 Hz may be the ideal resonant frequency, but the tonearm database matching grid seems to indicate that anything from 8 to 11 Hz or so is ideal. The 2M Black on an RB300 comes in at about 8 Hz.
And another thing: The formula may be able to give you the resonant frequency, but it can't tell you how strong the resonant frequency is, because that depends on other factors such as tonearm design and damping. I'm not sure how vulnerable the RB300 is to mass/compliance resonances.
There are certainly some designs that can dampen most of the resonance back down. For example, a cartridge's damper brush (such as is on the Shure M97xE and was on the V15 series) reduces the resonant hump by around 5 dB. Ditto for tonearms with fluid dampers. I'd rather have a 0 to 1dB resonant hump at 8 Hz than a 5dB hump at 10 Hz.