There continues to be confusion among audiophiles on how to properly align your cartridge on its azimuth. In this article, we will:
Explain azimuth and why it should be optimized
Share two common (but mistaken) ways in which it is often aligned
Demonstrate using a video why the only way to align azimuth is by electrical measurements
Offer an easy and inexpensive method to measure for ideal azimuth angle
What is Azimuth Angle?
Imagine you are miniaturized, standing on your record and looking straight on at the front face of the cartridge. Now picture that cartridge leaning to the left or right while the stylus remains fixed in the groove. A cartridge tilted on its azimuth angle looks similar to how a boat leans to its port or starboard side if there is too much weight on one side of the boat. In a perfect world, we would simply have the top of the cartridge perfectly level to achieve the proper setting
Why Should We Care To Optimize Azimuth Angle?
Aligning your cartridge on its azimuth axis is how we maximize the stereo separation between channels. Who wants the left channel's signal playing in the right channel and vice versa? Certainly not us!
However, in vinyl playback there is always SOME leakage from one channel to the other channel. Given a record groove in which only the left channel is modulated (that's the inner portion of the groove / the part of the "V" shaped groove closest to the spindle) and the right channel is completely smooth (unmodulated) you will get plenty of signal from the left channel speaker, but you will also get a small amount of that same signal being heard through the right channel. This effect is called channel crosstalk.
By BALANCING the crosstalk between channels, we will achieve the largest possible soundstage, the finest pinpoint imaging and overall "realism" will improve. When we have balanced our crosstalk between channels we will have done so by finding our cartridge's ideal azimuth angle.
There is another component to ideal azimuth angle having to do with signal phase relationships, but this is more an artifact of the zenith angle being less than ideal (and to a lesser extent, rake angle) and not as much to do with azimuth angle. This will be a subject of a future WallySchool! article.
Setting Azimuth Visually - WRONG!
Many audiophiles are still under the impression that the way to align the cartridge for best azimuth is to visually ensure the cantilever is perfectly perpendicular to the record surface. It is common to use a mirror for this in order to increase your sensitivity to the angle by a factor of two.
If the cartridge manufacturer AND the company that made the stylus/cantilever assembly for the cartridge manufacturer (they are often NOT one in the same) had BOTH done their job perfectly then this method would be perfectly fine. Unfortunately, it is quite rare for this to be the case - and it is fair and reasonable that it should be so since all mechanical assemblies must have a tolerance for parts alignment - yet it could be easily and effectively argued that current industry tolerances are too large for fine-line contact styli.
In any case, the visual method isn't even a good one to ensure the cantilever is perfectly vertical unless you have a way to also remove parallax error. Imagine you are looking at what appears to be a truly vertical cantilever and its reflection in a mirror. If you were to then move the position of your eye a couple degrees to the right or left it would suddenly appear to have lost its perfect verticality. You then change the azimuth angle so it looks perfectly vertical from that position.
So, which position for your eye was the TRUE position that eliminated parallax error and therefore offered you the best position for your eye from which to determine true verticality? Without a reference to eliminate parallax error, it is hopeless.
Besides, you will soon see that the ideal azimuth angle has NOTHING at all do with the cantilever nor the stylus.
Setting Azimuth Using Mono Signal - WRONG!
Another common method is to play a mono signal and invert one channel's inputs in an effort to find the azimuth angle that gives the lowest monophonic output. Unfortunately, this has NOTHING to do with maximizing channel separation and everything to do with balancing the output between channels. If you are doing this, please STOP!
It's The Groove And The Coils!
As you will see in this video, ideal azimuth is determined solely by the relationship between the 45-degree groove walls and the coil assemblies in the cartridge motor.