Speakers: Isolation?


Guys,

I’m trying to figure out the best method for setting down my stand mount speakers.

Currently I have a pair of hollow wooden cabinet stands ordered to measurement from eBay. These are pretty lightweight and do not use dense wood. They are laying atop thick butcher blocks acting as pliniths which are on a set of Mapleshade carpet heavyfooters (spiked). What’s the best way to effectively mount my speakers onto the stands?
madavid0

Showing 7 responses by geoffkait

Well, to be fair, the idea is not original and you can’t see them under the speakers anyway.
That’s why it’s a good idea to minimize the number of springs and maximize the mass. Since isolation effectiveness is inversely proportional to the Fr.


Whoa! Yeah, Baby! That's what I'm talking about! Everybody's doing it, doing it!

In case it’s not obvious, the total spring rate k in the equation is the k for each spring times number of springs. That’s why it’s a good idea to minimize the number of springs and maximize the mass. Since isolation effectiveness is proportional to the Fr.


toddverrone
Geoff - what’s the formula for Fr? You posted it ages ago and I never wrote it down..

Fr = 1/(2 pi) X square root (k/m), where k is total spring rate and m is total mass

For those who don't like equations use a stop watch to time the oscillations. That gives you Fr.
I generally like the whole idea of double stacking. Whether it’s double stacking with cones and plates or double stacking with a combination of springs and roller bearings or even stacking springs or stacking roller bearings. But one thing to keep in mind is that when the resonant frequencies of the two layers are the same or even close the two layers will naturally interfere. So, the trick, my friends, is to pre-calculate Fr for the two layers to avoid interference. For a dual layer heavy masses and springs system, for example ensure the spring rate of the lower layer is much lower than the upper layer. My Nirvana dual layer isolation platform is based on just that concept, using very heavy masses and steel springs.