I won't speak about all tuning forks, but the tines of a fork have properties of a tuning fork. I would say that the trough on the Triplanar is more rigid than are the tines of the fork.
08-27-10: Thom_mackris
We can discuss issues of rigidity until we are all blue in the face. Would you say that the thin bar that supports the damping trough is more rigid than say, a ... tuning fork?
However, you have to keep in mind that there are several factors that influence the resonant character of a tuning fork. Among those factors are the geometry of the object and the material properties of the object. I would encourage you to read the comment by Atmasphere:
This is an example of a statement that makes sense to me. To my observation, when I tap the Triplanar at various points, I found the tonearm to be very dead. I can believe that the material properties of the Triplanar dampen vibrations. So my empirical observations support what Atmasphere is saying. It is hard for me to imagine that such an apparently dead tonearm would be picking up the resonances that some here have claimed to be the case.
08-23-10: Atmasphere
The Triplanar has a extensional damping material on the arm tube to reduce mid and high frequency resonance artifacts. This is one of the reasons this arm is so neutral- most arm manufacturers do little to address this issue.
You are correct, people can discuss this stuff until they are blue in the face, but ultimately what counts is whether a person knows what they are talking about. In my case, I tend to make that determination based on whether I can make sense of what the person is saying.