Brave surgery, glad it worked out !
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You are indeed a brave man!
In addition to your sensible question to Tri Mai about the construction of the cap, I'd have been wondered about potential damage or dis-adjustment of the bearings from the pressures of filing, especially with the Riffler.
The ring I had (not a Clearaudio) was so wide that this method would not have helped, but I'm glad it did for you!
Glad you worked it out. It is unfortunate that one of the innovative features of the Triplanar (the tower to adjust VTA) which required that the bearing and tonearm assembly are offset to the right, is therefore also the cause of problems in mounting the tonearm on certain turntables, let alone problems in relation to using peripheral ring weights. For example, it is darned near impossible to mount a Triplanar on an SP10 Mk2 or Mk3, because the square escutcheon that demarcates the turntable chassis will not allow the Triplanar mount to get close enough to permit proper pivot to stylus distance, without also seriously skewing the mount clockwise, so that the tonearm would have to hang over the LP surface when at rest. (Obviously, I've tried.) I wonder whether this has been a problem with two other tonearms that in this structural way pay homage to the Triplanar. I refer to the Reed and the Talea. Anyone?
For every question about the Tri-Planar's choice of offset direction, there's an owner of a turntable which is limited to mounting the range of typical 9" tonearms.
With an effective length of 250mm (remember that 254mm = 10 in.) the offset pattern of the Tri-Planar yields a mounting center distance of about 213mm or approximately that of an SME and Linn 9" arm ("short" 9-inchers).
Choosing to offset to the opposite side would make the Tri-Planar mount like an arm that's longer than its 250mm mounting distance - not a smart move, IMHO.
In designing the Stelvio-II's tonearm mounting area, I wrestled long and hard - plotting the "landing pattern" of quite a few tonearms - then, deciding which ones to eliminate (if any) - to keep the base from becoming too unmanageable. Ultimately, I sacrificed the 12-inchers into custom territory - ones that could still be mounted but required an over-sized armboard.
As far as peripheral clamps are concerned, I've used them (and loved them) on a Merrill Heriloom. At the same time, this was plainly too much ritual to play an LP.
One of the outcomes of my platter designs was to maximize energy drainage from the LP without the need or resorting to any form of clamping.
I appreciate the benefits of clamping (both center as well as peripheral) to some designs. At the same time, the risks to cantilever damage (from periphery clamps) is VERY REAL, and something I encourage my customers to try at a risk to both their cartridges and their patience.
Thom @ Galibier
I agree with your assessment of ring weights. In fact, on balance I could live without record weights, record clamps, AND peripheral ring weights. (I now never use either of the former, occasionally use the ring.) Not only do they add to the necessary ritual of playing an LP, in my system they also can rob the music of some sense of liveliness that I delight in. I guess there is a point where excessive damping of resonance is not such a good thing.
Interesting thread. A friend owns a TTWeights Gem and tried mounting the Tri-Planar and when used with an outer ring found out about the problem mentioned above. He called the designer and was told to move the arm back by about 2mm and readjust all other parameters and then he could use the ring. The designer thought that not having the arm set at the exact 233.5mm pivot to spindle distance was a better option than not being able to use the outer ring clamp.
Thoughts by others of this solution?
Mounting any tonearm at a non-designed distance from the spindle necessarily alters the alignment geometry. It will be impossible for the stylus to track the arc across the platter that was intended by the tonearm's designer.
If an arm must be mounted farther from the spindle then the cartridge is normally moved outward in the slots by a similar amount. This allows zenith to be aligned at the points the arm was originally designed for (Baerwald for a TriPlanar), albeit with a flatter tracking arc. This in turn necessitates skewing the cartridge slightly in the headshell.
Whether the tiny reduction in tracking angle error from the flatter arc would compensate for upsetting the arm's intended force vectors from a skewed cartridge is impossible to predict with certainty. Personally, having heard both misaligned cartridges and rigs played with and without rings, I wouldn't bet on it and would want to compare.
BTW, whether it would even be possible to attain the TriPlanar's intended Baerwald alignment in your friend's setup will depend on the stylus-to-mounting screws dimension of his cartridge. Some cartridges wouldn't be long enough to attain alignment with the arm moved that far back.
I hope the designer knew which cartridge your friend was using and that it was in fact long enough to be aligned with the arm mis-mounted by 2mm. If not, his advice was in effect a statement that, "My ring is more important than aligning your cartridge properly". Unless he's tried it himself with the same cartridge and tonearm, he couldn't know that and his advise would be merely self-serving.
Even if he did know the cartridge could be aligned, I hope he advised your friend to compare the sound with (a) the arm and cartridge mounted normally, without the ring, and (b) the arm and cartridge mounted abnormally, with the ring. These setups would certainly sound different but I doubt anyone could predict which would be "better".
When forced to choose between compromises, the user should listen and decide for himself (or resolve the problem with radical methods, like our brave friend Kostas).