Discuss The Viv Lab Rigid Arm

Raul, Can you get it through your head that I am not claiming superiority for underhung tonearms?  I have written this many times.  I am only advocating an open minded approach to novel ideas, such as the idea of an underhung tonearm.  And in fact, how DO you know that a pivoted, overhung tonearm with headshell offset is the best option for pivoted tonearm design, besides linear tracking, unless you at least entertain other designs?  Have you auditioned the Viv or any other underhung tonearm?  Actually if you go to the Yamaha GT5000 website, you can find there a decent scientific justification for the underhung tonearm on that turntable, albeit I take issue with some of the points made there.

Raul, I apologize; the technical explanation for the underhung tonearm on the GT5000 is to be found on the "What Hi-Fi" review of the whole turntable, where the reviewer asked the Yamaha engineers for their explanation. He then had to translate the response from the original Japanese:

I thought I should ask Yamaha about its rationale for the tonearm length and the lack of anti-skating, and received a reply from no less a personage than Kiyohiko Goto, Chief Engineer at Yamaha Japan’s AV Division.

Regarding the tracking error he says: “A short straight arm has excellent tracking performance because the inside force is generated at the point of contact between a stylus tip and groove of vinyl and is always variable with the variate of the music groove. In the case of a short straight arm, its null point (= balanced point) is at the middle of the grooved area (so) the maximum tracking error is 10 degrees at innermost and outermost grooves. The distortion caused by this small error angle is inaudible because it is lower than both the tracing distortion and the residual noise. Furthermore, tracking error appears as phase shift between the left and right channels, and even at its maximum (10 degree) error the phase shift that results would be the same as caused by a difference in the distance from the left and right speakers to the listener of only 2mm. This also does not cause any problem for sound.”

As for the lack of anti-skating, he says: “A short straight arm does not require anti-skating because [at maximum error angle] if the vertical tracking force is 2g, the frictional coefficient is 0.3, and so the inside force (outside force) will be approx. 0.1g. In the case of a conventional offset arm with a maximum tracking error of 2 degrees, the inside force will be approx. 0.02g so the difference of the max inside force between a short arm and an offset type will be 0.08g at the maximum, thus the difference in force is very small.”

“On the other hand, when anti-skating is employed, because it applies a constant force it never cancels the inside force which constantly changes as its follows the music signal. The constant differences between the variable inside force at the stylus tip and the constant force by the anti-skating adversely affects the cantilever, hence the tracking performance is not stable. In a short straight arm the tracking performance following (the) music groove is excellent because the variable difference of force between the stylus tip and tonearm (cartridge) is not generated.

In my opinion, the real reason there is no anti-skate device is because AS would have to reverse direction by 180 degrees, before vs after the stylus gets passed the single null point achieved with any underhung tonearm. That would be difficult to manage. Whether AS per se is harmful for the reasons stated by the Yamaha engineer is a matter for debate. Whether distortion due to TAE is lower in magnitude than both tracing distortion and residual noise is an interesting claim that I am not equipped to critique. The bold type is mine in order to highlight that controversial claim. If the claim is valid, perhaps that explains why I hear no problem that I can relate to the extreme TAE, with my RS Labs RS-A1. In fact, the character of its sound across the surface of an LP, from outer to inner grooves seems more constantly the same than with conventional pivoted tonearms. This is only an opinion based on listening and with no measured data, of course.

@lewm , and in my pedestrian experience that is all clear BS. Not you, but the claims this person makes.

@clearthinker , now crank that experiment to the admitted 10 degrees. It's killing me. Anybody have a test record with synchronous sine waves in both channels? It will be easy to see the effect on a scope. 

Another important point @lewm made earlier is that an underhung arm is not free of skating due to the curvature of the record. the effect is going to skate the tonearm outwards toward the rim at both the outside then again on the inside. So at the most difficult area to track you are faced with both skating and a 10 degree tracking error. In my book that sucks. If any of you have not looked at the Reed 5T, the 5A and the Schroder LT you should. These are the solutions very bright people came up with that solve a host of issues. The only problem is that they require a lot of real estate, a table that can handle 12" arms at least.

Again, I’d prefer to compare underhung tonearms to conventional pivoted overhung tonearms. And my thought is that the more linear change in skating force from outer to inner grooves may be an advantage to underhang. Also zero headshell offset may be another. I’m just trying to understand why SQ is good, and I mean audible distortion is low.

The answer is plain. An infinitely long tonearm (or, as my physics mentor used to say with a nod to Newton and Liebnitz, "as near as makes no difference" in a strong Yorkshire accent), with no offset and it's one and only null point set near the label where it is needed most (for the density of musical information per unit length of groove). You know it makes sense, as the seatbelt campaign used to say.

Seriously, we cannot judge this tonearm until we try it. The arguments from its designer are sensible, but are they enough to overcome conventional wisdom? Only listening would tell us. I wish I were in a position to try it out!