In this thread post on down, we are discussing which side of the Replicant 100 stylus is relevant in calculating SRA off of vertical, and bblue said:
I thought continuing that investigation merits a new thread, so here it goes...
I am quite certain the Replicant 100 stylus is a variation of the Fritz Gyger stylus, with [major/minor radii] R/r 100/5 microns (hence the name), instead of the typical 80 (wasn't there a Replicant 80 before???). US patent US4855989 (pdf) is a translation of the original European and makes the following claims:
while the following figures show mounting options - figure 9 applies to how Ortofon mounts their stylus, and verifies my picture above:
The patent is short and very worth reading, as it also discusses its relation to a cutting stylus - Figure 3; notice the sole flat side:
Therefore, the SRA calculation technique for the A90 using trigonometry discussed in that other thread is sound (and applicable to all styli), if one can assert perfect stylus vertical to start with, and that requires a USB microscope.
I decided to look into all that after reading yet another confusing claim by Ortofon, this time on setting SRA on the new Anna:
and I had agreed. Here's my picture again, depicting vertical stylus:I had always assumed the right side of the tip was the actual angle of concern
I thought continuing that investigation merits a new thread, so here it goes...
I am quite certain the Replicant 100 stylus is a variation of the Fritz Gyger stylus, with [major/minor radii] R/r 100/5 microns (hence the name), instead of the typical 80 (wasn't there a Replicant 80 before???). US patent US4855989 (pdf) is a translation of the original European and makes the following claims:
The underlined is the most critical point here... Figures 4, 5, 6 and 7 are variations of the invention:1. A stylus for tracking stereophonic and quadrophonic sound grooves of gramophone records, comprising:
a stylus body having a tip, the tip of the stylus having at least one substantially flat surface which forms a front side of the stylus facing forward along said sound grooves during tracking, the stylus being prismatic with a square cross-section and having a surface forming the tip defining a shaped section with tracking edges, the shaped section having facets disposed diagonally to a longitudinal axis of the stylus, the flat surface forming the front side of the stylus leading in the direction of tracking along the grooves.2. A stylus according to claim 1, wherein the shaped section of the tip has a cross-sectional shape defining an isosceles triangle.
3. A stylus according to claim 1, wherein the shaped section of the tip has a cross-sectional shape defining a trapezoid.
4. A stylus according to claim 1, wherein the shaped section of the tip has a cross-sectional shape defining a circular section.
5. A stylus according to claims 2, 3 or 4, wherein the tip has a facet which corresponds to a base line of said cross-sectional shape, defining said front side of the stylus.
while the following figures show mounting options - figure 9 applies to how Ortofon mounts their stylus, and verifies my picture above:
The patent is short and very worth reading, as it also discusses its relation to a cutting stylus - Figure 3; notice the sole flat side:
Therefore, the SRA calculation technique for the A90 using trigonometry discussed in that other thread is sound (and applicable to all styli), if one can assert perfect stylus vertical to start with, and that requires a USB microscope.
I decided to look into all that after reading yet another confusing claim by Ortofon, this time on setting SRA on the new Anna:
The Stylus Rake Angle (SRA) is very important to the performance of the Replicant 100 stylus, and the long contact surface (the sharp edge) of the diamond should be close to perpendicular to the record surface when viewed from the side.