Cartridge alignment seems, in part, to be about positioning a three dimensional object in space. When we talk about it here we are using far more words than pictures. For me, it is important that descriptions of the alignment/adjustment process be very easy to understand and to do so using words whose meanings are obvious. A description can be lengthy if it is clear and easy to follow without a lot of mental processing required to go from words to either a picture in your head or to correspond those words with the cartridge itself.
Zenith.
Looking at a dictionary definition of Zenith: 1) "the point on the celestial sphere vertically above a given position or observer." 2) a highest point or state; culmination." Okay - that seems reasonably clear. But it does not seem to correlate with talk about a phono cartridge as a three dimenstional object in space.
More definition: "the zenith angle is the angle between a point of interest and the zenith - the point directly overhead. In a three dimensional coordinate system, the zenith is the axis perpendicular to horizontal plane." I for one do not see the connection to a cartridge or a stylus on a cantilever. (Terminology can almost seem closer fit to what is now called stylus rake angle. - but don't get bogged down with that.)
I too am open to alternative terminology. What I'm about to write is not a criticism but an example of what I see as part of the issue.
I looked at the instructions for using the original Wally Tractor, part of which describes getting the cantilever lined up exactly with a scribed line on the tool. Quote: "The cantilever MUST be located as an extension of the center line." The Wally Tractor instructions (which are generally quite understandable) do not include the word "zenith". So Wally (or JR) did not need that word to instruct on cantilever alignment.
The response was in terms of 'zenith error' (and 'tracing error') It does not seem effective to understanding, imo, to describe what we're talking about in terms of of how it can be wrong! I gather this is your offered definition of zenith error: "... the two-dimensional angular deviation from perpendicularity between the cantilever and the groove contact edges of the stylus when the stylus is viewed with its apex (technically, "vertex") aiming directly at the viewer."
Richard Mak (AnalogMagik) writes: "incorrect zenith angle will result in an incorrect alignment geometry even though the cantilever may be aligned correctly to the gridlines of your template." He describes 'zenith angle' as "...whether the diamond is mounted straight on the cantilever, or is it off-axis." That seems clear.
I conclude that talking about 'zenith' itself is not helpful. Talking about something we call 'zenith angle' is talking about ... what? ... a line bisecting a stylus front-to-back that is ... what? ... parallel to the sides of the cantilever? Someone can probably say this better or more eloquently; perhaps 'the stylus is mounted straight on the cantilever.' Of course in the term 'zenith angle', the zenith word adds nothing, imo. Zenith becomes almost a proper name, at best a shorthand for: the angle of the stylus on the cantilever.
To do what the Wally Tractor was partly aimed at, getting the cantilever lined up, or beyond that, getting the stylus lined up requires changing the Yaw Axis of the cartridge in the headshell, that is twisting the mounted cartridge left or right. The former is possible, and I'd say expected; the latter is not possible visually without expensive tools.
Can someone say the sonic difference for a given cartridge with a 1 degree stylus mounting error versus a 5 degree stylus mounting error?
All of this is over-wrought given the cost of hi-end moving coils. For cartridges greater than say, $6k, cartridge makers should provide certification that a given cartridge is within 2 degrees of correct stylus alignment. I wonder what would happen if people started sending cartridges back - "this stylus is too far out of alignment." /rant
Zenith.
Looking at a dictionary definition of Zenith: 1) "the point on the celestial sphere vertically above a given position or observer." 2) a highest point or state; culmination." Okay - that seems reasonably clear. But it does not seem to correlate with talk about a phono cartridge as a three dimenstional object in space.
More definition: "the zenith angle is the angle between a point of interest and the zenith - the point directly overhead. In a three dimensional coordinate system, the zenith is the axis perpendicular to horizontal plane." I for one do not see the connection to a cartridge or a stylus on a cantilever. (Terminology can almost seem closer fit to what is now called stylus rake angle. - but don't get bogged down with that.)
I don't care much for the term either. Since very few people are talking about it right now (though I think it will be common knowledge amongst vinylphiles in the near future) perhaps we can coin a better term. I'm open to suggestions.
I too am open to alternative terminology. What I'm about to write is not a criticism but an example of what I see as part of the issue.
I looked at the instructions for using the original Wally Tractor, part of which describes getting the cantilever lined up exactly with a scribed line on the tool. Quote: "The cantilever MUST be located as an extension of the center line." The Wally Tractor instructions (which are generally quite understandable) do not include the word "zenith". So Wally (or JR) did not need that word to instruct on cantilever alignment.
When you talk about zenith (zenith error, zenith tolerance, etc.), what is the object of your sentence?
Are you talking about the yaw axis of the cantilever relative to a line on your tractor of choice? Or the yaw axis of the stylus tangent to the groove? Or something else entirely?
The response was in terms of 'zenith error' (and 'tracing error') It does not seem effective to understanding, imo, to describe what we're talking about in terms of of how it can be wrong! I gather this is your offered definition of zenith error: "... the two-dimensional angular deviation from perpendicularity between the cantilever and the groove contact edges of the stylus when the stylus is viewed with its apex (technically, "vertex") aiming directly at the viewer."
Richard Mak (AnalogMagik) writes: "incorrect zenith angle will result in an incorrect alignment geometry even though the cantilever may be aligned correctly to the gridlines of your template." He describes 'zenith angle' as "...whether the diamond is mounted straight on the cantilever, or is it off-axis." That seems clear.
I conclude that talking about 'zenith' itself is not helpful. Talking about something we call 'zenith angle' is talking about ... what? ... a line bisecting a stylus front-to-back that is ... what? ... parallel to the sides of the cantilever? Someone can probably say this better or more eloquently; perhaps 'the stylus is mounted straight on the cantilever.' Of course in the term 'zenith angle', the zenith word adds nothing, imo. Zenith becomes almost a proper name, at best a shorthand for: the angle of the stylus on the cantilever.
To do what the Wally Tractor was partly aimed at, getting the cantilever lined up, or beyond that, getting the stylus lined up requires changing the Yaw Axis of the cartridge in the headshell, that is twisting the mounted cartridge left or right. The former is possible, and I'd say expected; the latter is not possible visually without expensive tools.
Can someone say the sonic difference for a given cartridge with a 1 degree stylus mounting error versus a 5 degree stylus mounting error?
All of this is over-wrought given the cost of hi-end moving coils. For cartridges greater than say, $6k, cartridge makers should provide certification that a given cartridge is within 2 degrees of correct stylus alignment. I wonder what would happen if people started sending cartridges back - "this stylus is too far out of alignment." /rant