Speakers on carpet over concrete

Completely decouple, no spikes at all. I didn't think people still used spikes on speakers. I've had to dig up basements and fix water, add drains and repair or replace waste pipes. All the guys with stereos in there basements use pods or springs, now. I haven't seen spikes in 15 years.. Spikes transfer a lot of the bass into the floor and then into the walls. It  smears the bass signal and vibrates the house.. The same in a house, spikes setting on spring pads maybe. :-) Spikes not so much.

I been using Townshend Podiums for over 2.5 years, they sure work well.

Decouple with individual springs, properly sized for the weight of your speakers or Herbies Giant Fat Gliders or Threaded Stud Gliders. Size individual springs by putting the actual load somewhere in the middle of the usable range, and account for any differences in weight distribution between the front and back of your speakers since the front can be heavier due to the weight of the drivers.

For a very low cost, cut squares of Owens Corning 703 or 705 rigid fiberglass, or use hockey pucks. The Owens Corning board is very similar to what is used in the AV RoomService EVPs.

If you want to pay more money look at Townshend, RevOpods, IsoAcoustics GAIA footers, or any number of other popular products. Some like Nobsound spring footers, which are relatively inexpensive.

Thank you all for some excellent options.  I didn't think the bass would vibrate the house due to the mass of the floor.  I'll start with the cheaper options like hockey pucks.

You do not want a speaker stand or a speaker resting on carpet and rocking about. You want to be sure that the speaker/stand Is in solid contact with the hard surface of the floor. My stands spikes make solid contact with the concrete beneath the carpet/pad. The stands are filled with Atacama Atabites...my stands do not budge, nor do speakers. Blutac is used between speaker and stand. 

I agree about not using spikes on a wood or composite floor, however if you have a pored concrete floor with carpet & pad overlay and properly spiked speakers, the floor is not going to absorb the bass. By using long enough spikes so the tips rest on the slab and the speaker cabinet bottoms are raised high enough to clear the carpet surface. You will have a solid, stable connection to the floor. Make sure you have sharp spikes and they are long enough.