This cartridge was sent to us here at WAM Engineering for microscopic and electrical analysis. The owner wanted us to determine the native Stylus Rake Angle (SRA), ideal azimuth angle and zenith angle of this cartridge. See more about it HERE. We found SRA and zenith to be essentially perfect (92.35 degrees and 0.2 degrees respectively) but the ideal azimuth angle was a whopping 2.9 degrees off level!
While this amount of variation from ideal is the largest we have yet seen for azimuth, let it be known that this cartridge was certainly one the most wonderful sounding cartridges we have heard to date. We enjoyed it enough to begin scraping together the $$$ needed to purchase one. If the azimuth angle on THIS cartridge was a cause for sonic deterioration, we certainly didn’t hear it!
WHAT IS CARTRIDGE AZIMUTH AND WHY WOULD I WANT TO OPTIMIZE IT?
We’re feeling too lazy to write about something that has been well covered before, so for this point check out Michael Fremer’s excellent two-part article HERE and HERE. Please read these if you are not familiar with what azimuth is and how to measure for it and then come back to this blog post when finished. If you are already familiar, read on!
There are two elements of Mr. Fremer’s articles deserving mention here:
The two most common ways to “adjust” azimuth for its ideal setting are not at all worthwhile methods. Both the approach of visually leveling the cartridge AND the approach use of a mono signal with one channel out of phase and listening for lowest output are both flawed methods for different reasons. The first approach assumes too much about the cartridge assembly and the second has nothing directly to do with the real benefit of getting your ideal azimuth angle dialed in – minimizing and balancing crosstalk!
The ideal azimuth angle of a particular cartridge is a function of two geometric relationships:
The angular relationship of the stylus groove contact surfaces with the cantilever. Ideally, the left and right channel contact surfaces will be at a 45° angle (clockwise & counterclockwise) to the vertical axis of the cantilever.
The angular relationship of the vertical axis of the cantilever to the coils. Again, the coils should be at a 45° (clockwise & counterclockwise) relationship to the cantilever.
If you want the widest, deepest and tallest soundstage with the greatest separation of instruments in space with pinpoint, stable imaging then you’ll spend the effort to optimize your azimuth. ‘Nuff said.
WHAT IS AN ACCEPTABLE VARIATION OFF LEVEL TO ACHIEVE IDEAL AZIMUTH ANGLE?
Cartridge manufacturers work with a certain amount of acceptable variation from the designed geometry in the construction of their cartridges. The acceptable amount of variation from the design targets is called tolerance. When any part is out of alignment beyond the tolerance limits, that part is faulty and should be repaired or replaced by the manufacturer. Regarding the stylus/cantilever assembly, the three primary geometric relationships to be sensitive to are the Stylus Rake Angle (SRA), azimuth and zenith.
By way of example, Lyra cartridges have a 2° tolerance for their stylus mounts. This allows them to sell a cartridge with a native stylus rake angle of anywhere from 90° to 94° (when measured under dynamic conditions – static measurements could be anywhere from 0.2° to 0.4° higher depending upon a few factors). The 2° tolerance also allows the stylus/cantilever assembly to have a ±2° zenith angle error. For clarification, the zenith angle is functionally the same thing as angular offset but measured differently – look out for much more to come from WallyTools on zenith. Of course, the 2° tolerance also allows Lyra to put to market a stylus that is not vertically oriented in the cantilever when viewed from the front which causes the ideal azimuth angle to be something other than a perfectly level cartridge. Further, if they also allow for a 2° tolerance in the coil mounts, then the ideal azimuth angle could conceivably be as much as 4° off level if both the stylus mount and the coil alignments displayed mounting error in the same direction.
Unfortunately, few manufacturers post their manufacturing tolerances.
HOW TO DETERMINE IF YOUR CARTRIDGE IS FLAWED?
With few manufacturers prepared to tell you what level of accuracy you should expect from your cartridge, we can use mechanical principles, mathematics and physics guide us. For SRA limits of acceptability, read HERE. For zenith tolerance limits, we will have a blog post for you following the launch of the WallyZenith.
When it comes to determining the limits of acceptable ideal azimuth angle, it is a bit more complex since ideal azimuth is a product of the two geometric relationships mentioned above. Consider if the stylus is mounted 3° in error clockwise and the coils are also mounted 3° in error but counterclockwise. When azimuth measurements are taken, the ideal azimuth angle will be somewhere closer to level (0°) as the two geometric errors partially cancel each other out (this is an oversimplification, but you get the idea). Unfortunately, in this situation a line-contact stylus that is raking your grooves in a cockeyed fashion isn’t doing the best job of it as one side of the stylus is reading the groove at the top of the “V” that forms the groove and the other side is reading the bottom of the groove, which causes other issues that are deleterious to playback.
Generally, we’d suggest a conversation between the owner and the manufacturer of any cartridge that is 2°-3° off ideal azimuth. If you have a cartridge that is off by 3°-4° you should expect the manufacturer to ask to have a close look at it for themselves. If it is off by 4° or more we would demand it.
Based upon what we have seen and measured, you should not expect that just because you spent multi-thousands on your cartridge that the stylus/cantilever/coil assembly should be perfectly aligned. We have seen MANY cartridges come through for analysis and we know it generally does not matter if you paid $1,000 or $21,000 as they all exhibit mounting tolerance errors that often have no correlation to their price tag.
It is important not to guess at your azimuth angle if you are going to begin a discussion with a cartridge manufacturer in which you are bringing their Quality Assurance practices into question. The WallyReference offers an easy, quick and very accurate method for measuring azimuth and SRA angles.
It is certainly to your benefit to KNOW your critical stylus/cantilever/coil assembly parameters and align the cartridge with those tolerance errors compensated for. It is our job at WallyTools to make that possible for you.