Stillpoints and reference-level speakers

Agear, I suggest the following easy experiment. Place on a normal office table a component that has a fan (which is neither very quiet not very noisy), e.g. a computer or an external hard-drive. After turning on the component, place your elbows on the table and a finger in each of your ear and listen to the vibrations generated by the fan that travel through the table. Then, place a cushion between your elbow and the table and listen again.

I predict the following outcome:

1) When resting on the table using your elbows you will hear very clearly and loudly these vibrations. (There is a decently strong coupling between our ears and the medium conducting the vibrations.)

2) When placing a cushion between your elbows and the table you will hear these vibrations significantly less. (The coupling has been significantly reduce in this situation.)

3) When removing your elbows from the table you will hear the fan but not the vibration generated by the fan that travel through the table. (There is no coupling in this situation).

Obviously, in the experiment suggested above the elbows play the same role the spikes play in an audio system.

The simple experiment suggested above should illustrate to everyone that spikes do not isolate. On the contrary, spikes increase the coupling between the spiked audio component and the surface on which this audio component rests. (In fact, even poor spikes like our elbows provide a decent amount of coupling!)

It is important to note, however, that this is not necessarily a bad thing. For example, increasing the coupling can be beneficial for subwoofers or speakers with large bass drivers. The large mass of the floor and the strong coupling between the floor and speaker provides a very strong foundation for the bass drivers, viz. the movements of the driver are less likely to induce movements of the cabinet of the speaker/subwoofer. (The strong coupling between floor and speaker will also change the spectrum of resonant frequencies of the floor and also of the speaker - because of the added mass and the change in geometry. Depending on the situation and also on the listener this may affect the sound positively, negatively or not at all.)

The problem with most spikes is that they allow vibrations to go in both directions. That is, not only from the speakers into the floor but also from the floor into the speakers. This effect is not desirable. The reason is that one wants to hear the music reproduced by the speakers, i.e. not the music produced by the speaker and modulated by spectrum of resonant frequencies of the floor.

The problem with most spikes is that they allow vibrations to go in both directions. That is, not only from the speakers into the floor but also from the floor into the speakers. This effect is not desirable.

The easiest way to test that hypothesis would be to do what John Atkinson at Stereophile did many moons ago. Attach an accelerometer to the speaker cabinet and see what happens with and without your grounding device of choice.

Nvp, When you have a sharp spike, you have many foot pounds per square inch from the weight of the component focused on that point. Mass means great inertia resisting motion. The expectation is that the component will be coupled to the shelf and then ultimately to earth. But that the floor's vibrations will have a hard time inducing vibrations in the component.

But as alway the proof is in the pudding-does it sound better. Brass spikes differ in sound from steel ones, etc. Clearly resonant frequencies of the coupling also matter.

Would you recommend only putting components on cushions? That might be taken as nonsense by some.

"Would you recommend only putting components on cushions?"

Not a bad idea, but only if really high quality high build expensive ones from an audio boutique type company.

Pier One just will not do. :^)

Guys, you are missing the point. The goal of the little experiment above was to illustrate that in order to isolate a component one has to minimize as much as possible couplings. I did not recommended placing speakers on pillows nor did I recommended to isolate them from the floor. I merely suggested a simple experiment that should provide some insight into the physics involved. (This experiment can be done by anyone that is not completely deaf, has a hand with at least one finger and a computer with a fan that is not completely silent, i.e. a significant amount of the audiogoners. How many people here have an accelerometer Agear?)

Regarding the two companies discussed here, I should point out that their philosophy and goals are basically the same. (In fact all top companies in this field tell about the same stories.) Both types of footers discussed here aim at draining out into the floor unwanted vibrations from the component resting on them, i.e. neither is trying to isolate the component. What is different is the way these devices are trying to achieve this. That is, one is increasing coupling to the floor while the other one is attempting to make the flow of energy unidirectional.

About the resonance phenomenon Tbg, any 2 or 3 dimensional structure has characteristic frequencies called normal modes of vibrations (or eigen modes or resonant frequencies). The normal modes of vibrations of a structure represent the frequencies for which the transfer of energies between a structure and a source of vibration is maximum. Now, the normal modes of a structure are determined by the geometry of the structure and the distribution of mass in the structure (i.e. they are specific to each structure). Consequently, when placing a heavy speaker on the floor the resonant frequencies of the floor and also of the speaker will be affected. How significantly the normal modes change will be and which of normal modes will be affected depends on: the type of floor, how heavy the speaker, were you place the speakers in the room, where your room is situated in the building (e.g. ground floor, 1st floor, floor 100). As such, one (i.e. user or manufacturer) cannot know before hand which of these devices will provide the best result. One simply has to try them in his/her system.

I hope I made it clear that I am not saying that one device/approach/company is better than the other one. I also hope it is now clear that I am not trying to provide a solution - there isn't a general one. Like Dr. Lesurf, I have merely tried to provide logical arguments that show why some reviewers, manufacturer, sale persons and audiogoners make silly claims when the say that spikes actually isolate.