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Old 13th Mar 2018, 1:21 am   #11
kalee20
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Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
Posts: 7,059
Default Re: Pre-amp for Golden ears

Quote:
Originally Posted by Craig Sawyers View Post
For what it is worth, the resonant frequency of a spring/mass (which is what an isolation mount for a valve is) is given by (1/2.pi).root(g/B)

Where g is acceleration due to gravity (9.81m/s^2) and B is how much stretch there is in the isolation springs. Therefore the resonant frequency depends only on the stretch of the suspension springs.

So if the springs stretch by 1 cm (10^-2 m), the resonant frequency is 5Hz, which looks fine. If they stretch by 1mm the resonant frequency is 16Hz, which is probably still OK.
It's a bit of a misleading formula, this - the resonant frequency depends on the spring constant and the mass. Nothing to do with gravity, the resonant frequency will still be the same on the moon. But! The Spring constant is also the extension divided by the force to produce said extension, hence the g/B calculation also works.
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