AnalogMagik Tutorial 3:
How to Set Azimuth on Your Cartridge.
Azimuth refers to the horizontal balance of the cartridge when viewed from the front. This, in turn, determines at which angle the stylus sits on the record groove.
The theoretical assumption is that when the Cartridge is perfectly perpendicular to the record groove, the stylus will sit perfectly in the record grooves. Visual methods using tools such as the Acoustical System SMARTStylus (an acrylic block with grid lines) or bubble levels offers an excellent starting point.
All cartridges are made by hand and therefore, the stylus may not actually be perfectly perpendicular to the cantilever, or the cartridge body. This means visual methods, can only provide you with an approximation. As soon as the record spins, whether your stylus is sitting at the optimal spot is unknown, so it is impossible to achieve an accurate setup by eyesight.
If azimuth is set incorrectly, the Stylus will not sit perfectly in the record groove, signals recorded on the Left Channel will leak to the Right Channel, (or vice versa), this is leakage between Channels is called Crosstalk, and it is expressed as a negative decibel number. The higher the negative number, the lower the crosstalk, the better the channel separation.
All cartridge will have some inherent crosstalk, high-quality cartridges will usually have a crosstalk above -30dB for both channels, whereas the average cartridge will usually have a crosstalk between -25 to -30 dB.
The AnalogMagik software and test LP contains two test tracks which all allow you to determine the level of crosstalk between two channels. To determine the optimal azimuth, take readings of the two Azimuth tracks on the test LP, and AnalogMagick will compute the Crosstalk number for you.
If Light channel Crosstalk number is > than the Right channel, twist the cartridge by slightly (by approx. 0.5 to 1 degree), and repeat the measurement, or vice versa for the other direction. An optimal Azimuth setting is achieved when the difference between the L and R Crosstalk numbers are as small as possible.
For Example, if you start off with -25.5dB on the left and -28.5 dB on the right, you adjust the azimuth and the numbers will change. Keep adjusting and measuring until the Crosstalk number is as close together as possible, .to say -27.5 and -27 On a good cartridge, it is possible to achieve a number that is as close as 0.5 dB between Left and Right Channel. On others, you can sometimes get as close to within 1-2 dB difference between channels.
We emphasize that meaningful results are highly dependent on the quality of the cartridge. Some cartridges have an imbalance to begin with, and no amount of adjustment will yield optimal results.
There are two important points on Azimuth which we must emphasize:
1) Azimuth is highly affected by "Landing Behavior" which we talked about in the Basic Alignment Tutorial. If your cartridge has uneven pressure exerted by a cantilever landing behavior which is not going straight up and down, chances are you will never achieve a satisfactory Azimuth Crosstalk reading.
2) Azimuth is also highly affected by Anti-skating, as well as VTF and VTA. If Antiskating is set incorrectly resulting in an uneven pressure on the groove walls, this will cause an imbalance to the Crosstalk numbers. Therefore, you just optimise Anti-skating in order to achieve an optimal Azimuth setting. Changing VTF and VTA may also affect Crosstalk to you may have to go back and forth between different parameters and find an optimal point which results in a good set of numbers between all parameters.
In rare instances where a correlation cannot be found, the AnalogMagik software also allows you to detect the phase shift as well as amplitude difference between the L and R channel, as a secondary measurement. You can adjust azimuth until the phase shift number is as close together as possible. However, this is not a very common occurrence and a correlation is often not established, nor is it repeatable. The Crosstalk measurement is usually sufficient.
If your crosstalk analysis leads you to have to tilt the cartridge by more than 1-2 degree, the cartridge is tilted too much and will likely throw off the other parameters. Over time, it will also cause suspension problems due to the weight imbalance. In such cases, we suggest that you go back and carefully examine your cantilever alignment's landing behaviour, and particularly anti-skating. Also reexamine VTF, and VTA.
Keep in mind that some cartridges have an inherent uneven L/R output as well as Crosstalk numbers out of the factory. In such cases, it is an equipment limitation - ie, there's nothing wrong with the program.
Again, an accurate analog setup is a balancing act between ALL and not just one parameter. The goal is to obtain optimal numbers in as many parameters as possible, so do not sacrifice one parameter at the expense of all others. This is why an an All-In-One tool is so important because no parameter can be optimised on a stand alone basis.