Speaker Spikes - Working Principle

@OP Carpet and underlay will not act a mass-spring-damper system. Locating the bottom of the cabinet in free space will not "change" the sound of the majority of speakers since they are designed to be set up in that way.

Ok , so set me straight. I have uber thick shag over extra heavy Gortex type padding. My house is a 35 year old cement slab build. I have a couple styles of speakers. Zu omens on spikes and JBL 4312A monitors on 3 leg Sound Anchor stands, both run spikes. Even with what a Sound Anchor stand weighs , I had to press them down to penetrate my floor covering and hit the cement. My floor covering is so thick and dense that without spikes the JBL & Sound Anchor combo rocks at the slightest touch. There’s no way I could run springs or pads. I purchased 4” think walnut slabs from Timber Nation and spiked them to use as footers under my Zu’s. They sounded like crap. I had conversation with the man himself in Utah and tried all his suggestions for spacing the Omens, nothing worked. The Omens on spikes leave maybe a 1/4” gap over the shag and have substantial bass, even with modest tube watts. I must admit I’ve yet to try stacking 2 completely different systems to make an Odd Couple ( pun intended ), but my spikes work pretty well. I think there’s some solid information in this thread, but it’s overloaded with theory based on reading articles Vs actual testing. I’m not saying people are wrong, but I’m saying some are being too absolute in their opinion. So I guess there’s more than one way to catch a fish. And please understand that my words are not meant to offend anyone, we have too much of that here. Happy Listening, Mike B. 

a good article on the topic

There are undoubtedly a variety of methods and configurations for devices and materials being used in bespoke permutations to assist with controlling energies generated within a Cabinet.

If Cabinet produced energies are not being transferred these energies are in many many cases going to have a impact on the sonic being produced, as the drivers will be affected by transferral of Cabinet produced energies into the drivers.

Fortunately for the Speaker user, if Cabinet produced energies are transferred away from the drivers especially to the level its presence has minimum impact, the use if bespoke Cabinet mounting or sandwiching of a Cabinet has been very worthwhile as a practice.

It is also known that in many cases, the bespoke methods for a Cabinets produced energy management can come with costs that for some will be seen as a substantial investment.

The last electronic device downstream of the Source that has the role of processing the Sources produced electrical Signal is the Speakers Xover. As the Electrical Signal moves from the Xover, it is only the Umbilical between Xover and Driver that has the final influence on the Electrical Signal to be delivered to the Driver.

Note: The following will be most suitable as a practice to be put in place, for a Speaker that is out of its warranty period. As many Speaker owners have owned their selected models for quite a few years, and some buy used to get access to the more affordable options, it will be quite common for Speakers to be out of a warranty period.

There are substantial improvements awaiting for the produced sonic, that can be attained by working with Xover and internal Xover - Driver Umbilical. Working with this element of the Speaker is not for everybody as it commonly requires a practice of working with a Soldering Iron, not all have the confidence to do this.

This as a method will entail exchanges of parts, where new parts selected will have the same measurements used that at the ones belonging to the circuit for the Xover. For the more confident in such practices this method can be taken a little further where the Speaker owner may choose a different measured value for a component to replace a insitu Xover component. 

 From a personal experience I have encountered Speakers having undergone this type of modification. I have been demo'd how a replacement part on a circuit, especially selected as a part, for being one that far excels the Manufactures selection made, as a result of their budget constraints, has transformed a Speaker produced sonic, to the point a the sonic produced leaves the perception a new speaker is seemingly in use. 

More recently I was demo'd a Cabinet Speaker I am becoming familiar with, that is mounted on Townshend Podiums, has a modified Xover (expensive parts selected) and uses PC Triple C wire as the Speaker Cable. 

As I am a  advocate of PC Triple C wire, and have been quite encouraging to others to experience it in use. The recent demo'd Speaker now has the PC Triple C in use as the internal umbilical as well the external Speaker Cable. The reports back are that something quite new is being detected, not night/day, but enough to strongly suggest the small cost and time allocated was more than worthwhile.

Tread carefully on the subject, but an investigation should prove if a practice such as exchanging wire used for the internal umbilical is reasonably easy to achieve. This as a practice is one I will strongly suggest as being a worthwhile undertaking, the suggested wire to be used for an exchange is already stated.          

So just an update on the Herbie's spike decoupling gliders I picked up, they're fanatic. Upper frequencies are cleaner, more detailed and have much more depth and nuance to them. Mid frequencies didn't change much for me. Lower register bass notes seem to have lost a ton of flab and vibration and are a lot more detailed and sharp. I did lose a ton of lower end grunt, but it's replaced with more detail from the bass notes and it sounds like instruments are being played rather than frequency loading a room with vibration. I would highly recommend anyone on a second story with carpet over wood subfloor try these out. They've increased detail, decreased bass flab and my wife downstairs doesn't hear the bass frequency vibrations nearly as badly. Speakers are Focal Sopra's in a small room.