To couple, or not to couple, that is the question

Mitch2

I do not want to offend anyone. I am just trying to prove a point. 

The solution you are using is - coupling. 

Mechanical ‘decoupling’ is not a science, just an audio belief until someone can defy gravity or prove otherwise.

Robert 

Sound Engineer & Vibration Management Consultant

Hello Robert – You are correct, "decoupling" implies totally separating two systems.  The proper term would probably be “damping” but this is one of those industry slang issues.  Decoupling is commonly used in the soundproofing and audio products industries and has been adopted by manufacturers, industry spokespeople, and audiophiles on these forums. 

Damping indicates the dissipation of vibrational energy, implying some portion of the energy entering a system is absorbed and ultimately changed to another form of energy such as heat, resulting in a reduction of the vibrational energy transmitted between the two systems.  This more accurately describes what happens when elastomeric materials are used between speakers and the floor.  The term "isolation" is sometimes used when referring to mass-loaded spring damping systems.  These types of vibration dissipation systems are prevalent in the automotive and machine industries.

As with many things related to this audio hobby, decades of point-proving and arguing have not determined a clear “winner.”  Audiophiles are inundated by manufacturers clamoring about how their products are “the best” and frequently using pseudo-science and marketing psychology to influence purchasing decisions.  At some point, all arguing aside, it comes down to a comment I recently read on a different thread, to paraphrase, “buy and listen to what you like.” 

Damping is using a material or device to take the energy out of vibration by transferring it to heat. The shock absorber on a car forces oil or gas through small passages. That takes energy, which becomes heat, in the process damping suspension movement. Materials like sorbothane, cork, a phone book, anything like that is a form of damper.

Damping only works when the two parts are coupled together. Therefore, damping is a form of coupling. The difference is when the material being coupled is rigid and inflexible we call this coupling. When the material is soft and yielding we call it damping. Either way, coupling.

Decoupling, or isolation, allows the isolated component to vibrate freely on its own. Because if it touches anything the physics of mechanical vibration dictates this vibration will propagate into the adjacent material.

We all know if you hit a table, the water in the glass across the other side of the table will move. There is even a famous movie where the first hint of the T Rex is the water in the glass. The glass that is in the car. The car with shock absorbers. Dampers. Coupled to the ground, car, glass, water.

Even with all that earth, tires, dampers, dashboard, and glass in the way the footsteps of the dinosaur travel right on through to the water. Only slowly. The vibrations are slowed and smeared, but still there. We all know this, which is why Spielberg uses it.

Damping is a form of coupling. It is damping and coupling that slows and smears. It is isolation that alleviates this. QED.

Even with springs, damping and resonances play a role in the effectiveness.  Robert's points, Max's springs, Herbie's elastomers, or the NHL's pucks will each perform differently wrt the transmissibility, amplitude, and frequencies of vibrations from one system (the speaker) to the other (the floor), or the other way around.  The audibility and effect on the resulting sound of an audio system will be unique to each system and room.  It is no surprise that there is no consensus here on what sounds best.

It is isolation that alleviates this. 

Yeah, I keep my speakers in the media room and listen in the garage.

Unless speakers are suspended via a silent air column, they are not 'isolated'

QED

???

Didn't see any 'proof'...