Purpose of triangular placement of cones/spikes?

RE: my previous post - I should identify that I am a manufacturer of vibration control products.

Barry Kohan

For a number of years it has been thought that a pointed cone provides vibration control by "draining" unwanted stored energy out of a component and restricting the movement of vibration up into the bottom of the component due to the small contact area of the point against the shelf surface. Some people have called a pointed cone a "mechanical diode" allowing energy to transfer in one direction but restricting the energy flow in the opposite direction.

A closer look at the interface of the bottom of the component with the top of the cone, the point of the cone with the shelf surface and the material from which the cone is made and its shape will reveal the true nature of a cone's capabilities and limitations. A component placed on a normal shelf is subject to external vibration trying to enter from underneath due to the transfer of energy from the speaker through the floor and up through the equipment rack, plus the shelf itself contains additional resonance due to its vibrating in sympathy with the air-borne vibration from the speaker.

Placing the component on a cone will change the nature of the stored energy present in the component by altering its resonant frequency. The amount of change will differ from component to component due to the way the bottom plate of the component will be damped by the amount of surface contact with the top of the cone, the pressure of the cone against the bottom plate, the resonant frequency of the cone (which depends on its material construction and shape) and the position of the cone on the bottom of the component. That is why some cones sound better in some situations than others. It is really "hit and miss", especially when you consider that a cone is a rigid device. Being rigid, it is IMPOSSIBLE for it to really stop vibration from entering from underneath a component. In fact, it readily transfers vibration into the bottom of a component, it just does so differently than the original feet did. Additionally, raising the component further away from the shelf allows more acoustic energy to reach the bottom plate directly from the speaker. Using only three cones under a component (a popular practice) which reduces chassis "chatter" by allowing the three points to more easily define a plane so the component will sit evenly, allows two of the component's corners to dangle unsupported. This situation is not desirable since the chassis can now be more easily excited by air-borne vibration.

A cone may sometimes be better than using the original feet on a component but it cannot stop or absorb unwanted vibration or resonance.

Barry Kohan

Hi Subaruguru,

My point (!) is that a cone is not exclusively a single direction transmitter of vibration. Being a rigid device it MUST transfer vibration from the shelf INTO the component that is resting upon it. The hard point is directly coupled to the shelf and the hard cone material cannot absorb vibration, it can only transmit it. If, as a cone enthusiast might claim, the point has such a small contact area with the shelf that it restricts vibration from passing up into the point, how can they also claim that the tiny point is able to "drain" the vibration so efficiently out of the component? Those two claims are mutually exclusive.

The much more important situation to consider is that the vast majority of vibration control products on the market (and also nearly all of the home-made variety) do not effectively address ALL three main sources of vibration that affect a component:

1) Vibration that is directly-coupled from the loudspeaker, and transfers through the floor and up through the component stand into the feet of the component.

2) Air-borne vibration sent directly from the loudspeaker drivers through the air towards the chassis of the component.

3) Self-generated vibration that is created within the chassis of the component by spinning motors, humming transformers and cooling fans.

The other significant sources of vibration are heating and air conditioning systems and exterior traffic (trucks, subways, trains, airplanes, cars, etc).

A component resting on the cone is immediately contaminated with vibration once any of the vibration sources are active. Attempting to "drain" the problem out is like closing the gate after the horse is out of the barn. The signal has ALREADY been contaminated and altered by the vibration and no amount of "draining" can undo the damage to the signal that has already been done. The most effective vibration control will be attained by thinking of the problem as a “system” and creating a method to place the component in an environment that eliminates as much of the vibration as possible BEFORE it can enter the component and affect the signal.

Best,

Barry Kohan

Disclaimer: I am a manufacturer of vibration control products.