Koetsu cartridges - what arms work?

Addendum.  Upon further thought, I do see your point about the skating force changing direction.  When the stylus is riding in the outer grooves moving toward the one instant when it is tangent to the groove, the tracking angle error is getting narrower until it disappears momentarily at the point of tangency.  Then the stylus keeps on riding toward the inner grooves, which is opening up the tracking angle error in a different direction until it reaches another maximum at the innermost groove.  This would also change the direction of the skating force.  My remaining point would only be that by my calculation, the max tracking angle error for underhung tonearms like the RS-A1 and the Viv is much greater than for conventional overhung tonearms.  Yet, with my RS-A1, I don't hear it at all.  In fact, the RS-A1 paints a smoother more coherent picture across the surface of an LP than do most overhung tonearms.  That is what makes me wonder if the real "problem" with most tonearms vis a vis skating force is created by the headshell offset angle.

 Racedoc, did you actually make quantitative measurements of skating force? Or are you reporting your observation of what the tonearm does on a grooveless LP? In any case the skating force will be a function of the friction of the stylus in the groove and the angle of tracking error. There’s no getting away from the calculation. I do question the importance of skating force generated by by tracking angle error.  The possible benefit of an underhung tonearm like the viv float is that there is no headshell offset angle which also generates a skating force that is additive with tracking angle error, at points on the LP where the cantilever is not tangent to the groove. And by the way examining skating force on a grooveless LP is fraught with sources for error. There is much less friction on a grooveless LP for one thing. 

Finally, I am not sure I understand your first sentence where you say that the skating force changes direction with the viv float. Can you explain further?

Racedoc, This is in response to your post of 10-13-2017.  Therefore, you may never see it.  I am not sure exactly what Peter Ledermann may have told you regarding skating force and the Viv Float.  But it most certainly does generate a skating force at all points on the LP surface except that one point where the arm wand (and presumably the cantilever/stylus) is tangent to the groove.  At that instant, skating force = 0.

Conventional tonearms can achieve tangency to the groove at TWO points on the playing surface of the LP, which is the whole reason for stylus overhang and therefore headshell offset angle.  However, even at those two points of tangency, there will still be a skating force, due to the headshell offset angle.

What the Viv and the RS-A1 may be telling us is that our obsession with tracking angle error is misplaced.

idl57, It's not surprising that the Koetsu tonearm did not float your boat. Upon close inspection of photos, it appears to be a Jelco tonearm in Koetsu guise, which of course raises its cost by a factor of 2 or 3 compared to a Jelco 750.  Not that Jelco tonearms are "bad" per se.  

racedoc,  Can you say more about the Viv?  I was in Tokyo a year ago and lingered in Yodibashi Camera in Akihabara for more than an hour deciding whether or not to buy a Viv.  They had all 3 sizes on display (7, 9, and 14-inch)  Which do you have? I calculated that tracking error goes down significantly when you go from 7 to 9 but from there going to 14 doesn't help enough to warrant the extra length, possible issues with resonance, and the difficulty in mounting.  I would have bought the 9-inch, had I gone ahead with purchase.  My interest in the Viv is based on my own home experience with one of the only other "underhung" tonearms on the market, the RS Labs RS-A1.  That tonearm is also more excellent than one would want to believe it is by just looking at it.  This led me to believe that underhang is a serious alternative, that tracking angle error is not such a big deal (because both underhung tonearms develop a lot of tracking angle error as they traverse the LP surface, more than with any overhung tonearm).  By inference, this also suggests that headshell offset angle IS detrimental to maximum fidelity. (For others, the headshell on an underhung tonearm is not offset at an angle to the arm wand.)

Thanks, Raul.  I got the idea that Koetsu's in general have very low compliance from what I have read on the internet, always a dangerous way to gather information.  I ran my Urushi in a Triplanar, which is medium mass; it "worked" fine, but I've never tested higher mass tonearms. If it's really medium compliance, it ought to work fine in a Triplanar and in any of several other modern high end tonearms that typically seem to shoot for "medium" effective mass.

It's not at all hard to believe that the 1200GAE is an "audiophile" turntable, and for the Koetsu, which has low compliance, you would use a tonearm with high effective mass.  How high?  I would say start at 12-15 gm and go up from there.  Some have said that the Fidelity Research tonearms are a great match; those have effective mass >25 gm.

Soundbuff, By all reports that I have ever read, the Urushi acts as if it does have a very low compliance in that it "likes" tonearms with high effective mass. For example, many have written in these forums that the Fidelity Research FR64S and especially the FR66S are "made in heaven" for the Koetsu cartridges. Can you quote your sources to the effect that the vertical compliance is higher than the manufacturer's published data? Also, can you say what is the effective mass of the T3b and the Original Live, respectively?

I own an Urushi and have only so far used it in a Triplanar, which is "medium mass" as tonearms go. I plan to try it in a FR64S soon.

Very nice TT, that Hanss.