For starters I think the "resonance diode" concept is far fetched. I cannot envision any theoretical basis for such a device, and simple cones do not behave as a "diode".
The principles behind resonance energy transfer are well understood and quite logical. But understanding how to apply those principles in real life situations is often very complex. That's where the art of audio design comes in.
I believe that elimination of vibrational energy is one of the most important parts of good turntable design. Vibrational energy cannot be removed but it can be converted into another form. Damping mechanisms of all types convert vibrational energy into heat. Damping and energy dissipation are synonymous terms. If a device does not convert movement to heat then by definition it is not a damper.
Another important principle is the conduction of vibrational energy. To dissipate the energy you often need to conduct it to a different place. That is where cones come in. They are often referred to as isolation devices but the opposite is true. Cones are very good at conducting energy and that is why they work well. Cones under a CD transport will conduct vibrational energy from inside the transport into the underlying shelf. Cones are effective when there is more internal vibrational energy than external. More often than not the worst vibrations are emanating from inside of a component. Yet common audiophile thinking is that components need to be isolated. If that were the case cones would make things worse.
Turntables in particular require energy dissipation. The stylus/record interface generates a remarkable amount of vibrational energy. To keep that energy from bouncing around and mucking up the sound it has to be dissipated (converted to heat) somewhere. In many cases the primary mechanism is the suspension. Even though suspension does provide some isolation I believe that the energy dissipation aspect is far more important. In fact effective isolation without energy dissipation would produce very poor results. Vibrations would have no place to go so they bounce around in the turntable causing trouble.
Most, but not all unsuspended turntables utilize some sort of internal damping to dissipate energy. We have found that loose lead shot is a very effective damping medium. Considerably better than constrained layer or any sort of
suspension. So the same principles are at work with both suspended and unsuspended turntables. The methods are different and the resulting sound is also different. However, I believe that the primary benefits of both are from energy dissipation and not isolation.
There is a common misconception that an unsuspended turntable is more susceptible to external vibration. In my experience there is little difference in absolute terms. Both types of turntable respond well to being placed on a rigid, stable platform. Both types of turntables can be negatively affected by footfalls and springy floors. Exactly how they are affected in a given situation may however vary widely. But as far as I can tell there is no inherent advantage for an unsuspended or suspended turntable. Better implementations will tend to be less affected. In many cases I think it is simply synergy. A particular design may work flawlessly with one stand, floor and room combination and perform poorly in another. Just read the forums. You will find diverse opinions and experiences not because people are biased or nuts, but rather the real life experiences understandably different.
While I do not think there is much difference in sensitivity to external vibration for suspended vs unsuspended turntables, I am not implying that they sound the same. I personally believe that a well implemented unsuspended turntables deliver more satisfying and accurate sound. But I certainly can understand why someone else may prefer the "suspended" sound.
