Filling speaker Stands?


I have a modest system. Continually look for ways to improve it's performance even to a slight degree. I have read many posts about improvements than can be achieved by filling the hollow spaces of some speaker stands with some type of material....sand, kitty litter, lead shot, and some others. Here are the stands I have......
https://www.sanus.com/en_US/products/speaker-stands/sf26/ 
These stands are of metal construction. There are 2 upright support tubes which are approx. 2" diameter. The stands sit on a carpet floor with spikes. On the top plates are a layer of Sorbothane and PSB Imagine B speakers sit on top of that. The 2 metal supports are attached to the base and top plate with just threaded holes about 1/4 " diameter. Pouring some type of dampening  material would definitely require a funnel.
The reason I ask this question is that, when I thump on each upright post, it rings for several seconds. A dampening fill would minimize this but would filling those posts really benefit the speaker performance to even a small degree given my modest setup? I don't know. Probably, few have experimented with this type of scenario.Thanks for any advice.



jrpnde
You need to dampen vibrations and that means more than just adding mass. Sorbothane is the only material I know of which actually converts the mechanical energy to heat, thereby getting it out of the system quickly. I recommend 1/4 inch self stick  sorb , of the densest form, 70 duro. Use small pieces of sorb eg. No more than 1 inch across and cover with 4 layers of electrical tape, so as to make this a constrained damping set-up. You can stick these all over your speaker, I place them on the front, and thus hide them with the grill. The effects are amazing. The big companies are only slowly moving this way. Search constrained damping and you will find a lot of speakers doing variations of this. Grado and Sennheiser are using similar damping on their phones, although with Senn it appears to be only with their top.models.
I use uncooked rice.  Your situation of a small opening will require that you find rice with a small grain size.   Advantages:  availability; low cost; moderate weight; non-toxic; non-magnetic; minimal settling and compression.   Rice provides some mass, along with excellent vibration dampening.

My advice:  Use fine sand and tamp it down well.

Why?  Deadens vibration and adds mass.

Lead has no advantages (and some setbacks).  And... it can be toxic.

I also suggest decoupling the speakers from the stands.  Sorbothane works, but you can even use four big globs of Blu-Tack (or museum putty, which is the same thing at 1/3 the price) near the corners.

Use fine sand and tamp it down well.

Why? Deadens vibration and adds mass.

Lead has no advantages (and some setbacks). And... it can be toxic.

I also suggest decoupling the speakers from the stands. Sorbothane works, but you can even use four big globs of Blu-Tack (or museum putty, which is the same thing at 1/3 the price) near the corners.


This is perfect advice, though tamping down the sand is a bit extreme, especially if is dry. 
Thanks to all offering advice. Seems that everyone has had experiences with all types of fill as to fill material and level of fill. With my current stand configuration I only have 2 options for a fill material.....sand or rice (if the grain size is small enough). Only one 1/4" threaded hole for access. So the tamping down of sand really isn't possible. I do use Sorbothane on the top plate between between it and the speakers. When I purchased these Sanus stands (which weren't very expensive) I did not consider the option to improve performance by filling upright supports to subdue the ringing of those by tapping on them. Maybe, with my setup, it wouldn't make any noticeable improvement. Only after buying the stands did I read about the benefit of filling hollow spaces in all types of stands. Probably, different stands would have been a better option.Thanks to all for offering suggestions.