

dlaloum wrote:The Shure Technical seminar paper provides actual wear data from lab measurements.... although their data appears to indicate that line contact styli (..) do reduce wear.
Our tests have shown that inadequate trackability, that is to say high mechanical stylus impedance, is by far the largest contributor to premature record wear or damage. In no way can a tip, no matter how well it is designed, prevent this type of irreparable damage. Examination of properly tracked grooves at 300 times magnification and greater has revealed that some modification to the groove is always visually detectable, regardless of the cartridge or the tip. A slight depression or shallow "trough" resulting from permanent indentation of the groove wall takes form in the first few plays. For most recorded signals, that amount of indentation does not significantly modify the reproduced signal. Assuming proper tracking and good record material, the "trough" is seemingly little changed after 50 or even 100 plays. In fact, some small amount of indentation is desirable to smooth roughness or irregularities in the surface of the groove wall, thereby keeping the surface noise low. In designing a tip, however, we would like to know how different tip geometries affect the shape of the record modulation with increasing numbers of plays. To do this, we have made many distortion tests. Following are some typical test results ...(..)....
......The results were highly variable among the tips with distortion levels sometimes increasing and sometimes decreasing. A decrease in distortion may be as much an indication of groove wear as an increase. The tip may hare modified the groove such that the distortion generated by record wear partially canceled distortion from other sources. No change in distortion indicates the least amount of record wear. 0n an average, the tests indicate a trend favoring the long contact tip, however, the benefit is highly dependent on the particular signal and the tracking force.
We have presented these examples to emphasize the variability of data and difficulty of obtaining conclusive results. Conclusions as to the quantitative effects on wear must be drawn with great care.
...(..)...Record wear tests were conducted as well. Second harmonic distortion was measured after 100 plays as outlined in the previous paper..... The results showed no significant difference among biradial, hyperbolic, and hyperelliptical tips.
Test 1: 2nd and 3rd harmonic distortion versus number of plays
Cartridge: V15 Type III
Tips: biradial and hyperbolic
Signal: CBS STR-100, bands 3A and 3B, 1 kHz
Tracking Force: 0.75 gram
Number of Plays: 100
Results: 2nd harmonic with biradial: no significant change on either channel.
2nd harmonic with hyperbolic: no significant change on either channel.
3rd harmonic with biradial: decreases about 33% of original value.
3rd harmonic with hyperbolic: decreases about 40% of original value.
Test 2: Same as Test 1 but at a tracking force of 1.5 grams.
Results: 2nd harmonic with biradial: increases by an average of 20% from original value.
2nd harmonic with hyperbolic: decreases by an average of 40% from original value.
3rd harmonic with biradial: decreases by about 33% from original value.
3rd harmonic with hyperbolic: decreases by about 33% from original value.
Test 3: Same as Test 1 except at 6 kHz.
Tips: biradial and hyperbolic
Signal: CBS STR-100, bands 3A and 3B, 6 kHz
Tracking Force: 0.75 gram
Results: 2nd harmonic with biradial: increases an average of 48% from original value.
2nd harmonic with hyperbolic: increases an average of 40% from original value.
3rd harmonic with biradial: increases an average of 40% from original value.
3rd harmonic with hyperbolic: decreases an average of 66% from original value.
Additional Notes: The changes in distortion values for styli from both groups exhibit decreases as well as increases. Decreases as great as 30% and increases of over 100% were measured.
Test 4: Same as Test 3 but at a tracking force of 1.5 grams.
Results: 2nd harmonic with biradial: average of both channels increases about 66% from original values.
2nd harmonic with hyperbolic: average of both channels increases about 25% from original values.
3rd harmonic with biradial: both channels increase an average of 45%.
3rd harmonic with hyperbolic: both channels decrease an average of 30%.
Additional Notes: Average initial 3rd harmonic distortion was higher with hyperbolic tips than with biradials, but final average 3rd harmonic distortion is about 25% lower with hyperbolic tips.
dlaloum wrote:My reading of the results, is that the hyperbolic tip appears to consistently provide better distortion results than the eliptical (bi-radial).
It is not clear whether this is due to reduced wear, or whether the wear is the same, but the line contact stylus has a lower distortion when reading a worn groove....
Results: 2nd harmonic with biradial: no significant change on either channel.
2nd harmonic with hyperbolic: no significant change on either channel.
3rd harmonic with biradial: decreases about 33% of original value.
3rd harmonic with hyperbolic: decreases about 40% of original value.
3rd harmonic with biradial: decreases by about 33% from original value.
3rd harmonic with hyperbolic: decreases by about 33% from original value.
dlaloum wrote:The chapter before this one discusses stylus wear, and one does tend to feel (intuitively) that where there is lower stylus wear showing reduced friction, there must also be reduced vinyl wear.
However there is no matching data to either confirm or deny this intuition here.
Results: 2nd harmonic with biradial: no significant change on either channel.
2nd harmonic with hyperbolic: no significant change on either channel.
3rd harmonic with biradial: decreases about 33% of original value.
3rd harmonic with hyperbolic: decreases about 40% of original value.
3rd harmonic with biradial: decreases by about 33% from original value.
3rd harmonic with hyperbolic: decreases by about 33% from original value.
Test 4: Same as Test 3 but at a tracking force of 1.5 grams.
Results: 2nd harmonic with biradial: average of both channels increases about 66% from original values.
2nd harmonic with hyperbolic: average of both channels increases about 25% from original values.
3rd harmonic with biradial: both channels increase an average of 45%.
3rd harmonic with hyperbolic: both channels decrease an average of 30%.
A decrease in distortion may be as much an indication of groove wear as an increase. The tip may have modified the groove such that the distortion generated by record wear partially canceled distortion from other sources. No change in distortion indicates the least amount of record wear. 0n an average, the tests indicate a trend favoring the long contact tip, however, the benefit is highly dependent on the particular signal and the tracking force.
dlaloum wrote:LD did I miss something?
dlaloum wrote:What I am saying is not related directly to wear - but I am stating that the resulting output after 100plays will be lower in harmonic distortion content when using a Line Contact stylus in most cases, and is unlikely to be worse.
dlaloum wrote:Clearly they were looking for and expecting a difference (so their intuition was the same as mine) - the results were inconclusive for wear (not for distortion... for wear), which they stated.
dlaloum wrote:The test was not however, trying to measure a relationship between VTF and wear. - Which is a shame! - leaves us with intuition again.
I just picked up a JVC 4MD-10X Shibata - VTF 2g.... my first high(ish) VTF line contact..... rather looking forward to listening to it.

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