Mepearson,
Linear trackers are specifically designed to address the theoretical shortcoming that you raised. They also, by eliminating the offset angle, eliminate skating forces. But, they raise their own set of problems, both theoretical and real.
The short arm tube can be an advantage, in terms of vertical weight, but it also means much higher sensitivity to changes in record thickness as far as VTA is concerned (short arm swings in a greater arc for any given change in height).
Most linear tracking arms have significantly higher mass in the horizontal plain than regular pivoting arms. This mass makes compatibility with the compliance of specific cartridges a bigger concern. Also because of this mass, and because linear arms are not relying on the mechanical advantage (lever/fulcrum) of a pivot, it actually takes more force to move the arm into the correct position as the stylus spirals toward the center of the record. This greater force may mean HIGHER degrees of deflection of the cantilever, hence more instantaneous error, in terms of deviation from true tangency, than a conventional arm (I have heard this argument made by some arm manufacturers).
Hence, even the supposed theoretical advantage of such arms are in dispute. That said, I've heard really nice performance from Walkers, Clearaudio, Kuzma, etc. arms. On the rare instances when my Mapenoll arm was not binding (bad arm pump), it too performed quite well. I currently stick with a Basis Vector arm, because of the very good performance and ease of use, though some tangential arms are tempting. The Kuzma, in particular, looks extremely well built and comes with high quality arm tubing, pumps, air reserve chambers, etc. I bet that is a far cry from the Mapenoll, in terms of reliable performance.
Linear trackers are specifically designed to address the theoretical shortcoming that you raised. They also, by eliminating the offset angle, eliminate skating forces. But, they raise their own set of problems, both theoretical and real.
The short arm tube can be an advantage, in terms of vertical weight, but it also means much higher sensitivity to changes in record thickness as far as VTA is concerned (short arm swings in a greater arc for any given change in height).
Most linear tracking arms have significantly higher mass in the horizontal plain than regular pivoting arms. This mass makes compatibility with the compliance of specific cartridges a bigger concern. Also because of this mass, and because linear arms are not relying on the mechanical advantage (lever/fulcrum) of a pivot, it actually takes more force to move the arm into the correct position as the stylus spirals toward the center of the record. This greater force may mean HIGHER degrees of deflection of the cantilever, hence more instantaneous error, in terms of deviation from true tangency, than a conventional arm (I have heard this argument made by some arm manufacturers).
Hence, even the supposed theoretical advantage of such arms are in dispute. That said, I've heard really nice performance from Walkers, Clearaudio, Kuzma, etc. arms. On the rare instances when my Mapenoll arm was not binding (bad arm pump), it too performed quite well. I currently stick with a Basis Vector arm, because of the very good performance and ease of use, though some tangential arms are tempting. The Kuzma, in particular, looks extremely well built and comes with high quality arm tubing, pumps, air reserve chambers, etc. I bet that is a far cry from the Mapenoll, in terms of reliable performance.