@lewm Chakster wrote that Oswald Mills Audio plinth is made of graphite. That is incorrect. They are made of Pennsylvania slate. Slate and graphite are two different things.
Wow, so it was my mistake then, mainly because those slate plinth looks identical to OMA graphite mats and shells. I watched a video how it was made (the plinth). Seems like they do not make any slate plinth anymore, now only cast iron.
OMA
Graphite mat and
graphite headshell "The OMA graphite mat is precision machined from an extremely high grade of polycrystalline graphite, not amorphous carbon, which is graphite dust in resin." -OMA
Also, perhaps paradoxically, use of a heavier counterweight could have the effect of reducing the effective mass of the tonearm overall. This is because the effect of the counter weight on tonearm effective mass is proportional to its distance from the pivot-squared, times the weight of the CW. Thus the distance from the pivot is dominant. And substituting a heavy CW for a light one will bring the CW closer to the pivot, all other things being equal.
This is where you are wrong, because IKEDA-SAN designed OPTIONAL
W-250 counterweight for FR-64fx
tonearm for use with his
FR-7f series cartridges. Cartridge alone is over 30g and counterweight is located very close to the pivot when i’m using FR-7fz on my FR-64fx. As you can see
in the catalog W-250 counterweight comes with FR-66fx tonearm, the 66 is higher mass arm.
To use FR-64fx with FR-7f series (or SPU) every owner need a heavier counterweight (W-250) for optimal performance on this particular tonearm. Bacause the stock counterweight for FR-64fx toneams is much lighter and smaller, to balance FR-7f it must be far away from the spindle which is NOT optimal for high mass low compliance cartridges. This is why W-250 was made by Ikeda. And it is
very close to the pivot when FR-7fz is mounted and adjusted. W-250 is bigger than heaviest counterweight you have with your FR-64s.
My comment was given for Fidelity-Research tonearm "FX" series.
Now i have two FR-64fx tonearms, one that i use ONLY with my FR-7fz
with W250 counterweight and it’s optimal for this combination according to Ikeda-San.
And another NOS in the box with stock small counterweight for conventional cartridges on conventional headshells that i’m gonna try on this tonearm in the future (Miyabi for example). "FX" series is so beautiful and i love it! I wish i could have black B-60 base for it. But now i have two N-60 for my FX beauties.
Anyway, my FR-64s with b60 is next to it.