We’re in the middle of our mini series on power and vibration control for our hi fi systems. Yesterday I explained that vibrations, caused by the loudspeakers in our listening rooms, were inevitable and instead of focusing on minimizing or eliminating them we would be better served to treat them like we would room reflections.
When you play speakers in the room you get reflections off the room walls. You can try and absorb and minimize those reflections or you can scatter and diffuse them instead. Over the years we’ve learned that diffusing them is a much more effective tack than absorbing and this is because when the reflections are diffused, our ear/brain mechanism will interpret them as random unrelated noise and easily ignore their contributions.
If we use the same technique on vibration and microphonic control we get the same results – that of the ear/brain ignoring their contributions. Diffusing is far better than reducing and here’s why.
If you try and damp out the vibrations occurring in your room you will be only partially successful – because you simply cannot eliminate them all. Whatever is left is still a focused and related ghost image riding on your music and, although reduced, it will still be perceived as distortion and smearing in your listening environment.
Cones and spikes under equipment, for example, reduce microphonic effects but don’t diffuse it – in fact they probably make it worse and here’s why. Cones and spikes work by reducing the contact area between the equipment and the vibrating surfaces. They are, by their very nature, extremely rigid and transmit specific frequencies to the equipment – thus further focusing the unwanted energy. Several manufacturers have used varying hardness materials within a cone to help this issue, but in the end their purpose is to reduce contact area and thus reduce surface-borne vibrations. The second problem they have is that they do not address airborne vibrations.
In fact, at least half of the microphonics issue comes from the airborne vibrations and, unless your equipment is in an acoustically shielded environment, there’s little any of these isolation bases and cones and feet can do to help. They are valuable under the speakers but I would recommend not using them under the electronics.
So the best answer is, again, diffusion and masking rather than absorption, isolation and futile attempts at vibration reduction.
Tomorrow I’ll show you how this works.