Fidelity Research FR-64 vs. FR-54

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.

Lew, I'm sure Ikeda likes his newer designs better.  J. Carr apparently does too, and he is a pretty smart dude. I have never heard Ikeda say anything negative about his older arms, however, and the newer Ikeda arms are a refinement of the FR arms.  As far as resonant properties, I have a hard time believing that the cartridge can cause resonance in the armtube above 100 hz - there is just too much compliance in the cartridge attachment to the headshell and the headshell attachment to the arm through the collet.

I am keenly aware of low compliance cartridges pushing the arm around at low frequencies, however.  This is the biggest source of thin, tinny sound.  IMHO, uni-pivots just don't work well with low compliance cartridges for this reason - the cartridge can and does rock the arm back and forth in azimuth at low frequencies. What the FR arms have going for them is high mass and beefy, outstanding bearings that don't give.  They have essentially no freedom of movement in azimuth.  The bearings in the Ikeda arms are even beefier.  That is why they work well with Koetsu's, Miyajima's and Ortofon SPU's.  These arms don't allow the cartridge to push back and cancel half the bass in the groove.

BTW, I have an MDC-800 (The Arm) on a SOTA Sapphire and an FR-64fx on a tricked out VPI HW-19 Mk. IV.  I tried my Miyajima Shilabe (low compliance) on my SOTA setup first and wasn't impressed with the bass, (which this cartridge is known for).  I then switched it to an FR headshell and tried it on the VPI HW-19 Mk. IV.  It had better bass than my Ortofon Synergy SPU, (aka the Rach 3 ball-buster !), on the same arm and table.  

The MDC-800 has outstanding bearings, so I reasoned that I needed more arm mass and inertia about the cartridge.  I added 3 grams of weight to the cartridge end of the MDC-800, remounted the Shilabe to the arm and tried again.  This time it matched the VPI set-up for bass.  The weight increased the moving mass of the MDC-800 from ~13 grams to over 16 grams, and it made a huge difference in sound.  You can't stress cartridge / tonearm matching too highly.  Many high end cartridges and tonearms are just plain incompatible and can cause endless frustration and head-scratching for many, many vinylistas !!

Raul,

BTW, I also have a Mission Mechanic tonearm, (the one GB Tools built after the Zeta Black VdH), on a Denon DP-75 direct drive in a custom birch plywood / black acrylic plinth.  This tonearm is like a Zeta on steroids !!  Sounds pretty good for an old tonearm and turntable.  I can't imagine what it would cost to replicate this thing from scratch today.  I'll send you some photos if you are interested.

Raul,
 Good to hear from you.  No arguments with your and Mr. Carr's observations, but I have just not experienced any resonant problems with my FR-64fx with any of the cartridges I've used it with, (Ortofon SPU, Shelter, Miyajima, Koetsu, Clearaudio MM).  I like it because it is the best removable headshell arm I have personally encountered.  I have not personally used a steel FR-64S, so I don't know if they act the same as the anodized aluminum FR-64fx, and I would guess the anodizing does provided some level of self-damping, so there could be a difference.

 I love the SOTA Sapphire / MDC-800 combination.  It works pretty well with everything I've tried on it, but the arm does benefit from a more headshell mass for some low compliance cartridges like the Miyajimas.

  I'm not real crazy about many newer "affordable" turntables, BTW.  Too many shortcuts on suspension and hardware for my tastes.  It's better to by a classic and rebuild it.  SOTA's factory-rebuilt Sapphires etc. are BARGAINS.

  My point it all this is that cartridges and tonearms have a complex and finicky relationship with each other which very few folks really understand (including, unfortunately, most of today's dealers).  You really need to find someone to help you match the cartridge you like to the tonearm it will work with, or you're in for a lot of frustration.  There is no universal tonearm that works well with everything, despite a lot of design effort in this area.

Lewm, Micheal Percy Audio sells some damping material called "EAR TAD Damping Foils" that 3M makes that is supposed to be the "cat's meow" for under damped tonearms, according to the dudes over at DIYAudio.  It's relatively cheap, but the trick is figuring out how much is enough.  You apparently don't want to wrap your whole arm with this stuff, but a little bit at the worst nodal spots is said to eliminate any ringing.  I'd guess halfway down the arm would be a good place to start, but I've never tried it.  I wonder if any other audiogon fans have ?