Diamonddears, I'm no mechanical engineer, but a spring has a resonant frequency (it's "rate"), above which it isolates whatever is sitting on it from whatever the spring itself is sitting on, and below which it does not---the mechanical energy passing right through the spring, un-attenuated. The isolation resembles an electronic filter, with a roll-off slope beginning at the center frequency. A turntable suspension, therefore, should have as low a resonant frequency as possible, 3Hz being an attainable number. The lower the desired frequency, the "looser" the suspension, and the slower the table will bounce when pushed down upon. A table tuned to a low resonant frequency will have soft springs, like an old Cadillac.