Cleaning my stylus the other day, I noticed what must be slivers of vinyl. I am using a .3x.7 mil elliptical stylus tracking at 1.5 grams. Tracking force and grove tangency was carefully set with external stylus weight and alignment gauges. So I did some investigating and came up with a potential answer which I have not found anyone else to have ever suggested.

In all the sales literature and analysis of stylus tip shapes, an elliptical stylus tip is depicted as having a shape like an true ellipse, with rounded edges (See Fig.1 on page 2) -- but this is not actually the case. An elliptical stylus starts off as a conical, with a flat surface cut on the front and back sides. As we all remember from high school geometry, the intersection of a plane and a cone produces an ellipse, hence “elliptical“. But there is a sharp edge where the plane and cone intersect. This is verified by looking at on-line microphotographs of elliptical stylus tips. The horizontal cross section through an elliptical cartridge will then look like two convex arcs connected by parallel lines. I have also seen cross-sections drawn as two hemispheres connected by parallel lines, but this shape neither corresponds to the photos nor manufacturing process.

Although these stylus tips are finely polished, an edge line is formed at the intersection of the plane surface and the curved surface, which radius of curvature must be an order of magnitude less than the advertised minor radius of 0.2-0.4 mils. This advertised radius probably refers to the distance between the front and back planes.

Concerning this edge line at the intersection, either one of two conditions must be true:

1) The edge does not contact the grove wall. In this case , the stylus must trace the grove just like a conical, because the surface that touches the grove has the same radius of curvature as the conical it was machined from. There is no improvement in tracing distortion. Then we should bring back Dynagroove.

2) The edge does contact the grove wall. In this case, there will be the improvement in tracing distortion claimed for the elliptical type. But the edge contacting the vinyl is not the smooth rounded edge of an ideal ellipse as depicted in the drawings in cartridge literature and engineering calculations, but this chisel-like edge, shaving off vinyl on each pass.

So I tried to examine the condition where the stylus meets the grove myself, using no math or equipment, but by creating a large scale model of groove and stylus. In a spreadsheet program, I printed graphs of parallel sine waves of various frequencies (see Fig.2 on page 2); then I drew circles with flat ends inside the parallel grooves using a draftsman’s template. This process shows that the edge line does bit into the groove, as Shibata claims. As the “elliptical” stylus travels along the groove, “pinch effect” still causes vertical modulation of the stylus. The narrower the distance between the two flat ends, the less the pinch effect.

Therefore, I would recommend using an elliptical tip only when archiving a record, when fidelity is paramount and the record will not be replayed. For repeated enjoyment of a record, use the conical tip. Moreover, the higher tracking force taken by conical tips will improve trackability, given the same cantilever design and tip mass, since we know from Newton’s laws of motion that the ability to accelerate to a high recorded velocity is proportional to tracking force. The elimination of harsh mistracking may be more pleasing to the ear than the harmonic distortion due to tracking error

Of course, the best option, for those who can afford it, is some kind of elongated contact stylus.

Have cartridge manufacturers been believing there own advertising art departments and “misunderestimating” the record damage potential of ellipticals these past 45 years, or is this analysis wrong?