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In Reply to: RE: Believe the measurements or my own lying eyes? posted by ColoKurt on April 18, 2017 at 15:35:24
you're seeing an exactly equal amount of crosstalk (-30db) in both channels. Is that the case?
Other guys mentioned, and you already know, that the azimuth adjusted for best crosstalk numbers electronically may result in the azimuth angle off 90 degrees, as in your photo. Someone else noted that this can be due to an imperfect mounting of the stylus or a bent cantilever; it can also be due to misalignment of the generator within the cartridge body. If it is not square with the top and sides of the cartridge body, electronic azimuth adjustment will tell you to adjust the cartridge body off the 90 degree angle with the LP, so that the generator itself ends up 90 degrees to the plane of the LP surface. I think this is most often the real problem. My only issue with your angle of adjustment is to wonder whether prolonged use might ultimately result in either aberrant wear on the stylus tip or wear on the suspension, due to the angles of the force vectors thus created. John Ellison used to say, and may still say, that if the angle is more than 2 degrees off 90 degrees, you've got a problem that is best rectified by replacing the cartridge.
In my personal experience, I have a Koetsu Urushi that ended up noticeably off center when I adjusted azimuth using my Signet Cartridge Analyzer (a vintage piece). Moreover, it did not sound very good. After pondering this dilemma, I decided to ignore theory, and I set up the Urushi so it was at 90 degrees azimuth, disregarding the meter entirely. It sounds MUCH better that way. And I don't worry about the nature of the wear on the stylus/cantilever.
I think it is far more important to have the tip (azimuth) perpendicular to the groove (particular for Line Contact types with a large bearing radius). For an elliptical tip (made with front and back face cuts), this is important since the contact patch is pear shaped. A tip azimuth error will result in a different effective scanning radius on each wall. It is even more critical for a Shibata since the effective SRA is defined by the cut and the curving contact line will result in a differing effective SRA on each wall.
Aligning for tip azimuth may or may not correspond to the body being normal to the surface since cantilever rotation (and skew with MC) is incredibly common and the mounting tolerances for the tip itself are of the order of 1 degree (Expert stylus) for SRA and/or tip azimuth. Shure allow up to 3 degrees (I recall reading somewhere) and a recently purchased Ortofon 2M Blue would suggest that Ortofon allow up to at least 2 degrees error.
In my experience, aligning the tip itself results in a significantly cleaner presentation and improved imaging even if the channel balance is off for the lateral signal.
"Beauty is Truth, Truth Beauty.." Keats
in fact my experience with my Urushi is consistent with what you say, assuming that at about 90 degrees azimuth the tip of the Urushi stylus is perpendicular to the groove. It almost certainly is more nearly perpendicular than it was when I aligned for electrical perfection. This was using a Triplanar, so azimuth was easily adjusted and was no factor in my results.
However, by your preferred method, the only way to align for azimuth with real accuracy is using a microscope/camera capable of imaging the stylus tip in the groove. Yes?
Evidently, the OP aligned for EQUAL amounts of crosstalk in each channel, which I assume is why he reported only one value (-30db). There is another school of thought that says to align for lowest amount of crosstalk, regardless of whether the values for each channel are equal (usually they are not, when you adjust for lowest amount). I have sometimes found that adjusting for lowest crosstalk but not necessarily equal crosstalk results in less deviation from the 90 degree ideal.
Yes! I do indeed use a USB microscope with a mirror, then scrutinize the still photo to refine the azimuth of the tip.
I appreciate that not everyone will have the tools at hand to use this method. However, the cost of very adequate USB microscopes is such that they are within easy reach of all but the most impecunious of audiophiles!
I definitely don't go for the "equal crosstalk" method as the channel imbalance and frequency response anomalies that affect nearly all cartridges to a greater or lesser extent will mean that one rarely gets "all of the stars in perfect alignment" as it were!
The reason for my rejection of the "equal crosstalk method" is that I have styli where the tip happens to be "perfect" in terms of perpendicularity with respect to the body and the channel separation was anything BUT equal which I put down to coil variances. If one went for equal crosstalk, one would actually introduce a significant tip alignment error and drop the crosstalk to a lower value. I did many experiments to prove to myself that the tip itself was the important parameter. Peter Ledermann stressed this in relation to the OLC tip which I had put on a Denon DL160 - Having seen the shape under a microscope, it is evident that it wouldn't tolerate much alignment error before it was no longer sitting in the groove sensibly!
"Beauty is Truth, Truth Beauty.." Keats
I don't go for equal crosstalk, either. For one thing, the best you can do is equalize crosstalk at the one test frequency, usually 1kHz. That doesn't mean you've achieved equality at other frequencies. I've never seen or played with the Foz, but I get the impression that it is designed to get the user to equalize crosstalk, but I certainly may be mistaken.
I agree with you on the importance of "tip alignment", but I would have guessed, and I always thought, that the reason most/many cartridges don't achieve optimal crosstalk numbers when the cantilever is perpendicular to the LP surface is due to off-axis orientation of the generator (coils and/or magnets) up inside the cartridge body. Which we cannot usually visualize directly.
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