Integrity Hi-Fi tru-glider tonearm

I wrote the word "scraping" as in the verb "to scrape". I did not write "scrapping". OK, so in my reading of the Tru-Glider website and viewing the photos of the arm, it is evident that the arm hangs freely by a thread. For the purpose of discussion, let’s refer to the connection between the thread and the arm wand as a "pivot". Below the pivot, the arm wand seems at least to have a cylindrical solid metal extension aligned in the vertical plane below the junction between thread and arm wand. In addition, there is a needle point attached to the base of the arm which is rigidly held in place at the base. The website says that if and when the "pivot" (junction between thread and arm wand) moves horizontally in response to stylus drag or other forces that one might imagine are transmitted from the cartridge, the inside wall of that vertical cylinder will bump against the needle point, thereby delimiting the degree to which the pivot can move around in horizontal space. I used the word "scraping" to describe what would happen when the needle and the inside wall of the cylinder come in contact. Period. Sorry for the tedious description, but the idea is tricky to communicate with just words.

Incidentally, I know full well that the Schoreder tonearms with a string bearing are otherwise conventional overhung pivoted tonearms.  I cited Schroeder only to say that the idea of using a string bearing is not new to the Tru-Glider.

As I read the latest posts here, I see there is much commonality between the Schroeder Ref SQ and the TG tonearms.

The Schroeder’s string attaches to the top of the tonearm’s structure. The string’s endpoint attaches directly under the arm tube through an "attached-to-the-tube" convex magnet. Another magnet below, which appears to be a flat surface, attaches to the lower end of the tonearm’s structure. So no, the Schroeder arm does not pivot around a string; it simply hangs from a string as does the TG.

The key adjustment is the gap between the magnets. Frank’s documentation suggests that a business card gap works well. I have experimented with this and found that the shortest gap possible provides for the greatest bass extension. I start with the magnets close so that I can barely get the smallest feeler gauge through the gap. I raise and then lower the arm over an LP, and observe that the arm’s lowering down to the LP. With the magnets tight, the arm slightly shifts along the horizontal axis on its way down. I make very small adjustments to the gap until lowering the arm results in a smooth, i.e., no sideway shifting, all the way down.

I will leave it to the mechanical/structural engineers to debate the benefits of the magnetic coupling below the Schroeder's arm tube and no coupling below the TG’s arm tube.

I could not attach a closeup picture of the Schroeder’s string/magnet view here so I added such a picture in my virtual system page.

John

It’s an ingenious pivot, but it is a pivot. What’s so wrong with calling it a pivot? By all accounts Schroeder tonearms are among the best. 

@

Good way to look at it, grk. Schroeder firmly constrains the pendulum motion with magnets, which effectively moves the pendulum's pivot down to the junction of string and arm wand.