Carpet and Floor standing Speakers?

I had the same problem. Mapleshade makes what they call " Carpet Piercing. Heavyfeet" Replace your speaker spikes with these large, heavy Brass footers with extreamly sharp, long pointed ends.
My carpet is very thick with a heavy backing, these footers had no problem piercing it right down to the wood. (plus you will get the advantage of heavy brass footers)
Ask for a Mapleshade catalogue.

Your speakers just sitting on carpet are not performing at all.

You can go a couple different ways on this depending on your room. If you would like to couple the cabinets to the floor, then you will need narrower spikes with a more tapered tip to puncture through everything (carpet, pad, vellum) and rest firmly into the concrete. This can help the floor to help reproduce lower frequencies than the driver/cabinet is able to under it's own area. This is "transducing" with your floor helping. This is most noticeable on subfloors or other materials as concrete has greater mass.

If you have the sub setting on carpet (and subsequent pad beneath) then the cabinet is isolated from the flooring... this can tighten bass but loose much of the lower frequecies generated by using surfaces as attached transducers.

A nice amplifier with good power across the spectrum, good speaker placement, room treatments and proper use of parametric EQ's will make most of these differences null. The only thing left is the "tactile" feel of having the sub coupled / attached to the flooring spreading to nearby walls... frames... walls.

Setting speakers on carpet may or may not affect anything depending on Proper EQ and room placement / measurements / volume.

Moving the speaker a foot may have more of an impact than the footers... just depends on more factors than a simple fix.

Hope this helps!

I've got similar issues. My speakers came with somewhat blunt brass cones
that did not pierce my carpet. When I was making my custom maple bases, I
bought sharper spikes to try.

Well, the first problem I encountered was that my concrete floors are not
evenly surfaced (unlikely yours are as well.) Even a slight discrepancy in floor
level is going to create issues with unsteady speakers if you are using four
cones. I used nylon washers in various thicknesses to compensate. To be
honest, after all the tweaking, I didn't hear a bit of difference between the
two cones. My speakers weigh about 125 lbs. each, so they really compressed
the carpet/pad to the concrete underneath. I had also carefully plotted
speaker placement with test tones and a decibel meter. I think Audiavreseller
is right when they say it's not a cut and dried issue.

Another problem I encountered was that after fussing with the leveling
washers, the spikes didn't couple to the bases as well as the stock cones and
were prone to buzzing at specific frequencies at high volumes. In the end, I
took out the aftermarket sharp spikes and reverted to the stock cones. If I
had wanted to mess with reconfiguring four contact points to three, obviously
that would have solved the contact issue. But as I said, I didn't hear any
difference. Your mileage may vary. One things certain, I gained a new
appreciation for how much work a speaker manufacturer goes through in
developing every aspect of speaker's design!