Fidelity Research FR-64 vs. FR-54

Dover, Your logic is impeccable. My memory was not, and anyway I should have thought more about what I wrote.  The actual case is that even with a slightly lighter than OEM headshell and even with the Acutex (lightweight) cartridge, the CW is very close to as close as it can get to the pivot, with the assembly just balanced horizontally, at zero VTF.  So I then used the dynamic to dial in VTF.  If anything, I need a lighter CW.  And your post reminds me that I did look for the W170 on eBay and Audiogon but have not found one.

I do in one sense like it the way I have it, because having the CW as close as possible to the pivot is a virtue in terms of minimizing effective mass, in view of the high compliance of the Acutex.

I suppose that to make a light CW heavier, you could also use those lead weights that are normally used in wheel balancing.  They would tape right up against a cylindrical CW, like the one on the FR64S.

Lewm,
The original W170 is hard to find. Best place is Japanese market.
This company makes copies....  
http://www.vcyoyo-mitsuke.jp/shopbrand/034/O/

The FR 64fx is anodized aluminum where the FR 64S is steel.  The big difference is the moving mass - 20 g for the 64fx vs. ~ 30 g for the 64S.  The 64fx and the 66fx are the most expensive arms FR made.  They are specialized arms intended for low compliance MC cartridges.  (If you don't like them, it is probably because of cartridge compliance mis-match.)  I am using my FR-64fx with a Koetsu Urushi and it is a match made in heaven.  My Koetsu guy says the Koetsu cartridge was developed to match the FR-64 arms and I believe it.  They also work really well with Ortofon SPU cartridges.

In my post of 01/31/17, the one preceding Dover's last post, I should have written "because of", not "even with".  It is because I am using a lighter than OEM headshell and a very lightweight MI cartridge that the CW has had to be moved so close to the pivot.  Don't want to confuse anyone any more than necessary (heh-heh).

dcbingaman, Wouldn't it be the case that the FR64S and 66S are better suited for lowest compliance MC cartridges, because they are, respectively, higher in effective mass than the fx versions?  So, you might say that the fx tonearms are best suited for low/medium compliance cartridges.  I own an Urushi, too, and one of the reasons I bought the FR64S was to suit the Urushi, because I have read that the two are well matched.  So far, I haven't gotten around to trying that combo, however.

I accidentally came upon the posts by J Carr, in which, like Raul, he mildly criticized the FR64S/66S tonearms for their resonant properties.  Raul was not wrong in mentioning that he had J Carr on his side in the debate.  J Carr seems to prefer the later Ikeda tonearms and some others, to the FRs, and he mentioned that Ikeda himself prefers his later tonearm designs to those he designed for FR.  I think, in audio as in other pursuits, context is everything. I still have to go by what I hear in my system with the particular cartridge that I am using.