How will you go from that information to determining the resonance frequency and Q?
What frequency range do you want to begin isolation? Do you have a way to verify whether the isolation platform makes things better or worse?
I just noticed in your first or second post in the thread you wrote "they did the engineering work" but it was not really clear who "they" referred to. Is this exercise because you need to buy springs at McMaster-Carr, or you already bought springs from somewhere else, that place did the engineering work to determine which springs to sell you, and now you are trying to work backwards to determine how they decided which springs to sell you?
Indeed I have serious doubts about the capability of the spring supplier to oversee the whole evaluation process.
In order to make it right, a solid understanding of tone arm/cartridge is necessary.
Ideally, the resonance frequency and amplitude should be known.
The elastic suspension is a LPF, where the spring is the inductor, the total suspended mass is the capacitor, and some king of solid or liquid friction the resistor.
The input of the filter is the displacement due to noise or schocks; it is variable, could be a permanent sinewave or a step/pulse.
The lower the resultant corner frequency, the higher the attenuation. That would suggest using a very heavu cradle and very soft springs, but that would be impractical since it could result in large displacements not compatible with the space limitations.
It is essential that the resonant frequency of the suspension be significantly lower than the tonearm/cartridge resonance, which is usually about 7-12Hz. IINM, Paul mentioned less than 1Hz, which is about 3 octaves below the tonearm/cartridge resonance, which would result in about 36dB attenuation of this crucial band, eve, if the damping is not very ggod.
Now, I believe the supplier, given just a few elements, like corner fequency and suspended mass (which he would probably translate as load
), should be capable of giving a plausible answer.