Showing 10 responses by hiho
The pivoting cantilevered plate that holds the arm has a guiding mechanism underneath it that extends to the back of the arm in parallel with the arm that points to one of the 3 points in the Thales circle. I know Frank's arm does not exactly use the Thales geometry but it is the reference to check for absolute tangency. Think of the Thales tonearm by Michel Huber in reverse. Instead of pivot the headshell with a guiding rod, the Schröder arm pivots at the arm-base. Frank is clever enough to conceal all the extra stuff underneath that plate that holds the armlift. And it's aesthetically pleasing. I wish there's a close up picture that shows all the mechanics but so far it's a trade secret. All I know it's done magnetically to have the least friction. If you're familiar with the Garrard Zero 100 tonearm, there's a guiding rod along with the main armwand and the Schröder uses the same concept except it done at the arm base area. Again, if you have the time, check out my thread in diyaudio forum. Here are couple pictures: http://i43.tinypic.com/9sxnh3.jpg http://i42.tinypic.com/2d11ocz.jpg The segment from point B to point D is where the guiding mechanism is. _______ |
Mark is right about the design's "exquisitely elegant simplicity." And this picture gives you all the clues on the design of its tangential guiding mechanism. _______ |
Just think of the stylus to the armwand as a straight line and the stylus to the spindle another straight line and the two lines form an angle and as long as that angle always maintains 90° then it doesn't matter what the base is doing or whether the arm goes in an arc or not. And it will track tangentially. The same theory applies to the Thales tonearm, except it pivots at the headshell, whereas the Schroder has a fixed one with no offset angle. The Schroder does not use the Thales geometry but having an understanding of the Thales semi-circle will give you a better idea. The advantage of the Schroder and Thales tonearms is that they do not have to use linear bearings with its enormous horizontal mass. The Schroder also has advantage over the Thales of having little to almost no skating force, hence the absence of anti-skating adjustment. Ingenious indeed! Thales semi-circle _______ |
More close up picture and pictures from patent. Hope they help clarifying the concept. Picture 9 Picture 10 Picture 11 _______ |
I am still looking for a picture that shows the bottom of the plate that covers the magnetic guiding mechanism. Understandably it would require, if possible, an awkward low camera angle or having the tonearm upside down. The patent drawings spell out the obvious, but I still would like to see an actual image. _______ |
I don't think that's possible because the Schroeder SQ is a version of unipivot arm and it cannot "move" the extra pivot. The only way to retain the string concept is to have a servo linear slide. Frank is a genius so he might be able to come up with something that combine the two methods but I don't see it to be practical. However he did make an experimental string arm in the form of a Thales concept with a pivoting headshell before. Even though it still achieves tangential tracking but it behaves dynamically different from the LT model. ______ |