Linear tracking tonearms.....

Peter, Most linear tracking arms I've seen have slotted head shells. So they can be adjusted to compensate mis-alignment by other adjustments, like VTA, and VTF. Most have a protractor with a straight line (instead of an arc), with lines that are 90 degrees off the main line to line up the cantilever (zenith).

One exception is the Thales Simplicity. With the design of the Simplicity you would have to take the head shell off, to align it, in it's jig. This is not ideal because you can not align the stylus with a load on the suspension. Since we know that different VTF will change the alignment (overhang), there is no way to know for sure if it's perfect or not.

As said above, if the alignment is off on a linear tracker the zenith will be off a little all the way across the record. Not sure how audible that is but I will look at Dgarretson's link about that.

Even though the Thales Simplicity is a pivoting tangential tracker with its own idiosyncrasy, you can still align it using traditional methods. You can use a typical paper template or protractor to confirm alignment. Since there's no overhang and supposed to be tangent, then wherever the stylus on the template the cantilever should be 90 degree pointing to the spindle. Typical template has two points on the arc, inner groove and outer groove. Draw additional lines on the template to confirm you have more than just two points are tangent.

You can draw your own template: find the effective length (Thales published a nondescript "9 inch") which should be the distance between the left armwand's headshell pivot to armbase pivot, and draw an arc from base pivot to spindle and draw multiple lines intersect with the arc and then draw perpendicular lines double distance all the way back to the Thales triangle. Voila, you have yourself a template you can use to confirm alignment. This way, you don't have to blindly follow the headshell alignment jig.

Bottom line is to have the cantilever always perpendicular (90°) to the radius or pointing to the spindle. In a traditional pivot arm, you only have two tangent points but the Simplicity is tangent on every point.

See GIF so you get an idea.

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Hiho, that's true. You still have to take the head shell off to make an adjustment, because you can't get to the cartridge screws with it on the arm. That's allot more awkward, and will take much more time to dial in.

There is also the Bergmann Magne tonearm.

The ET2.5 or latest generation or Kuzma airline offer some of the best of the separate linear trackers that you can buy outright. I have only experience with the Maplenoll (ET2 are similar) arms and have been very pleased. I have not experience the cantilever deflection stated earlier but my custom design mods have significantly lowered the mass of the original arm, I ran a UNIverse for 5 years before i dropped it (argghh) with no ill effects. I have been highly interested in the Kuzma but just can't seeing dropping 5000 grand on an arm when i have one that really suits my table well. I really dont have experience with the high end pivot arms so i cannot make a fair comparison. But the Linear arms are easy to set up and consistently perform well for me