Are linear tracking arms better than pivoted arms?

Following a near 3 decade hiatus from records, I acquired via AudiogoN a VPI HW-19 MKIV with an ET-2/Benz Glider combo...I've been mesmerized by tangential arms since I first saw the beautiful Rabco ST-7, as a teenage nascent audio-enthusiast, in magazine adverts and the beguiling B&O 4002, in person...I favored the Transcriptor Vestigial for radial arms. I suppose I'm examining it from a different angle :-)

Enjoy!
Sam

Atmasphere is absolutely correct.

"The idea that a pivoted arm of correct effective mass is going to induce greater side-to-side excursion than an air-bearing straight-tracking arm strains credulity."

I would even say it neglects fundamental aspects of mechanic and physic.
But nothing in physics can be obvious enough not to be questioned if it doesn't fit the preference of an audiophile. Must have been a test of true insight and scientific brilliance.
Oh my.

02-27-10: Dertonarm
I would even say it neglects fundamental aspects of mechanic and physic. But nothing in physics can be obvious enough not to be questioned if it doesn't fit the preference of an audiophile. Must have been a test of true insight and scientific brilliance.
Oh my.

Main Entry: snarky
Pronunciation: \ˈsnär-kē\
Function: adjective
Etymology: dial. snark to annoy, perhaps alteration of nark to irritate
Date: 1906

1 : crotchety, snappish
2 : sarcastic, impertinent, or irreverent in tone or manner

— snark·i·ly \-kə-lē\ adverb

I have been doing some research on the issue of stylus pressure that a pivot arm vs a linear arm exerts as the record progresses from the outer edge to the inner grooves. There is some pretty good information on the airtangent and Kuzma airline arms concerning this issue. In fact i found one reference where a reviewer compared the Airtangent to an SME arm on a VPI table. In addition, I had several discussions with some pretty good engineers who helped me understand the issue a little better. After going over it several times, I recognize now what Dertonarm, Raul, Atmasphere, and others were trying to relate. The easiest way to say it is that for two tonearms of equivalent mass, the pivot arm will result in less pressure applied to the stylus and suspension system of a cartridge as the stylus moves across the record. If you state the issue as forces applied and represent the forces as vectors in the xy horizontal plane. (assume x axis is the path of the linear arm), the linear arm forces are entirely represented by the x vector. As the pivot arm actually strikes an arc across the record, the distance the stylus moves is further and part of the forces is represented in the x axis and part of the forces are in the y axis. In addition, the pivot point also reduces the net force needed to move the arm. It is a similar to why a lever can lift a 100 pound weight with less than 100 lb downward force. Having said this, the better linear arms attack this issue by having less total mass that a typical pivot arm. The airtangent site clearly indicates this issue and explains how they attach this issue by using the spindle as a fixed part and using a bearing sleeve as the moving part as well as using a carbonfiber armwand to decrease weight without giving up stiffness. In addition, the manufacturing tolerences of the arm is pretty small to minimize the "Slop" that Dertonarm indicated was an issue with these types of arm. Similar comments are also on the Kuzma site outlining their approach to the problem. I ended up addressing this issue (by accident) as I modified the maplenoll arms by eliminating the aluminum wand and heavy, cumbersome vta adjustment bracket with a carbonfiber arm, spindle and wood headshell. My arm on my apollo is a very short ceramic armwand and very lightweight spindle. I have not compared the total weight to my modified arm on my ariadne signature but i believe it is lighther due to the very small length. Obviously, without the vacuum platter, this short length would be an issue. I appreciate the various contributors to this string as it opened my eyes to some more opportunities to continue to improve the system i have. I have invested pretty heavily into some top notch cartridges and understanding this issue better will help me protect that investment. Having said this, I do like my modified arm and look forward to trying to develop a smaller mass arm for my apollo.

Dear Oilmanmojo, let me briefly add that the vertical mass in the best linear trackers does indeed match the mass in most pivot tonearms.
But the horizontal moving mass is a completely different manner. In the pivot tonearm the mass in more or less equally dissipated on both sides of the bearing - i.e. on two antagonistic levers.
As it is moving around a center it puts no additional force on the stylus (if the bearing is any good....) especially so, as the bearing, armpipe (aside from slight off-set...) and cantilever are in line.
In the linear tonearm the horizontal mass is pushed forward by one (cruel...) lever only and at the tip-toe of that lever is the stylus /cartridge while most of the mass is far away but has to be moved by your stylus and the suspension.
The force pulling from 90° off which is not what your cartridges' suspension system was made for.
This dilemma was minimized by attempts as the ones of Lou Souther and Versa Dynamics with ultra short armpipe - only to add problems in other areas (very sensible to wrap/height changes in vinyl (the Versa Dynamic did feature vacuum hold-down for good reason - it is mandatory with its tonearm)).
I still believe that the striking and logic promise of linear tonearm will one day bring out a design addressing all the big problems - but so far this has not been done.
I haven't seen yet a linear tonearm really taking into account the way the suspension system of any cartridge is working.