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Old 19th September 2019
Gear Addict

Originally Posted by Starlight View Post
Nothing complex but what a lot of time this fascinating topic can eat up!

What is the aim of the f0? To be different to any of the modes? For example, if I have two lowest modes of 1-0-0 at 29Hz and 0-1-0 at 38Hz, should my aim be to get the f0 below 29Hz or is between them at 33 or 34Hz alright? Or, should the f0 be below audible frequencies, let's say below 10Hz?
Fo or fs is the resonance frequency of the construction.
At this frequency the construction is theoretically not damped and will move very easely when exited by sound with this frequency so isolation is here minimal.
Isolation starts at the sqrt of 2 x this fs.
So trying to get fs as low as possible will provide best isolation.

It has in principle nothing to do with modes, although if you have a flimsy drywall construction with a fs that is by accident tuned at a mode you will have mode cancelation in the room (nice) but a problem with isolation (bad).
Using tuned membrane absorbers to tame modes can cause severe ptoblems regarding sound isolation.