Adjusting Azimuth by ear

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I have seen that many people are concerned with correct azimuth setting. Having recently experimented with this subject, I decided to share my findings with the group, in case they are useful to other people as well. I am using a Clearaudio Souther (linear tracking) arm and a Clearaudio Titanium cartridge. My findings are of course specific to this material, though the conclusions might be applicable to other systems as well.
To set Azimuth on my above new cartridge, I thought of applying the electric measurements for crosstalk as suggested by Brian Kearnâ€™s influential 2002 article. Not having the proper material in hand, I decided to check if those millivolts produced by crosstalk are audible, or if it is something that only equipment can measure. After all, why bother with something if it is not audible?
To check this, I used HiFi News test record, which on band 4 of side one produces pink noise (i.e. a sound containing equal energy in all audible frequencies) on the left channel only. I put my headphones on, switched the balance fully to the right (i.e. the â€œwrongâ€ channel) and put the volume at a very high level. What I noticed was the following:
1. Cross talk was clearly audible, albeit low. This is not a surprise. My cartridge states 40db of channel separation (which is excellent), so I guess that if you are producing a sound at 70db on one speaker, up to 30db are expected to leak to the wrong speaker.
2. There was a lot of record surface noise at those loud levels, at various frequencies mostly high ones. Although the human ear can easily distinguish leaked pink noise from surface noise, I am not sure that a voltmeter can do that even if you serially attach a capacitor (which excludes low frequencies) as suggested by some people.
Next, I decided to play around with azimuth to see if I could minimize the above crosstalk. This turned out to be an extremely tricky exercise because it appears that the azimuth â€œsweet spotâ€ is extremely narrow (see below). If you are slightly off, there is an audible difference in crosstalk, but this doesnâ€™t really change from little off to much off. As a result, by tilting the head, there is no audible difference in crosstalk and furthermore as you donâ€™t have a clue if you need to tilt it slightly to the left or to the right it is practically impossible to accidentally locate the sweet spot.
Trying to figure out how to deal with this problem, I realized that I could slightly lift the entire arm system while the record was playing, dynamically altering azimuth. Although this also affects VTA and tangency, it turned out to be extremely useful in determining potential benefits from tilting the cartridge slightly to the left or to the right. This procedure helped me to identify the perfect azimuth setting in a few minutes only. Confirming other peopleâ€™s findings, it turned out that the correct range is indeed extremely narrow. While you are in that range there is practically no crosstalk, while if you are slightly off, crosstalk increases substantially but doesnâ€™t deteriorate much if you move further off.
I was so pleased with my findings and decided to move on to the other channel (band 5). I was assuming that the proper setting would be identical on both channels especially for such an expensive cartridge. But, disaster! The other channel was producing a huge amount of crosstalk! I tried to change again azimuth settings, but still crosstalk remained very high, always much higher than the other channel. With huge frustration, I decided to take the system back to the dealer. Fortunately, he accepted the fault and replaced my Titanium cartridge with a new one (they offer 3 year warranty).
Going back home, things looked OK this time. The two channels react slightly differently in the sense that the optimum azimuth range is quite narrower on one channel than on the other, and also in the sense that the absolute minimum is not exactly the same on both channels. Nevertheless, I did find a point (approx 1 degree off the vertical) where crosstalk is extremely low on both channels, and close to the minimum of each independant channel.
Note that to measure how many degrees I am off the vertical, I measured the height from the platter to the top of the cartridge on both sides, and found the difference to be 0.5 mm. Then I measured the cartridgeâ€™s width at the top which was 2.5cm. I then applied in MS Excel the formula Degrees ( Asin (0.5 / 25) ) = 1.1. I must say that it looks worse by eye!
I hope these findings are useful to other people troubled with azimuth.
Aristides

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Topic - Adjusting Azimuth by ear - Aristides 02:48:35 05/07/07 (1)

Re: Adjusting Azimuth by ear - andyr 05:50:46 05/07/07 (0)

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