dlaloum wrote:Are there problems with this paper, are there methods and assumptions that supersede the measurements described, or is it still spot on?
I like this article, and think the author has amongst the better grips of what is going on I've read.
Along with a vast body of published papers, the author assigns the top resonance to groove indentation spring and effective tip mass. If this is true, your method for optimising loading isn't too good, DL. Because much would then depend upon specific vinyl composition, and spring properties of the test discs you use.
Amongst supporters with published papers endorsing the vinyl indentation link to top resonance are big names, like Mr Shibata, for example. This is what you have to overcome to safely ignore groove-mass interaction. There are complete models, and on the face of it, it's well explored.
I'm in a firm minority here in not accepting that groove indentation happens during play. Rather that cantilever flexes. Actually, they're very hard to tell apart. The key difference, IMO, is that energy would be left behind by indentation. But conserved in cantilever flex. And when I do the sums, there's not enough energy by way of drag to support indentation.
There are published, peer reviewed, complete models for the top-resonance. Based on indentation. Which describe the whole thing very well. On the other hand, I personally have a model not based on indentation, but just cantilever flex, which describes the whole thing well too.
But, you can't really stand with a foot in both camps. There is only one resonance, so both indentation and cantilever flex can't both occur. For your purposes, DL, it matters to know which it is.
AFAIK, mine is the only analysis that describes a cantilever only answer. I might just be wrong, of course !
I'm sure I've posted this before to you, DL, in the context of it not being safe to assume the top resonance is due to cantilever flex. Personally, I can see a sound reason why indentation might not happen, but can't see a reason cantilever flex wouldn't. So I prefer cantilever flex.
However, if you decide to be anti-indentation, and support the minority cantilever flex camp, a whole raft of stylus profile preconcepts have to go too. Such as fine line contact areas.......and you have to say that a whole raft of published literature is wrong. But, I don't accept indentation happens during play, that is my opinion, FWIW. And I don't see contradictions. Everything is tidier.