shibata or microline, pls respond ONLY if you specifically have tried both.

Hi JC,

Thanks for writing.
Yes, on the Linn, those SHOULD be absolutely parallel. But as you know, since the armboard is not an integral part of the suspended sub chassis plate which has the main bearing, due to some anomaly, those are not absolutely flat in my case. There is about 1.5 mm warp. And as a result, I am not able to balance the table perfectly. It may be a defective sub chassis.

I may upgrade to an ’integral’ unit where both the armplate & the bearing plate are just one machined piece, like the Keel or something cheaper.

cleeds, "Zenith" is not something I made up.  If you have a pivoted tonearm with headshell offset, and if you then alter azimuth by rotating the arm wand back near the pivot (BEFORE the headshell offset angle is introduced), then the headshell itself not only rotates in the vertical plane described by azimuth but it also changes angle in a second plane which would alter the horizontal.  That affects VTA and probably affects the contact patches between stylus tip and groove in ways not favorable, slightly.  For example, if you rotate to the right or to the outer grooves of an LP, to change azimuth in that direction, then the rear of the headshell dips downward a bit with respect to its leading edge.  That action is changing zenith.  How important this is, I would not care to say, but it's real.  From a purist point of view, it's best not to change zenith while changing azimuth.  This can only be done if you rotate the headshell about its own longitudinal axis, without changing position of the arm wand.  I didn't intend to make a big deal out of this, but it is real.
You apparently subscribe to the physical definition of perfect azimuth, making the stylus square to the groove walls above all else.  Some others do it electrically, which does not always leave the stylus tip square to the groove.  I am actually coming over to your way of thinking after years of doing it electrically (least measured crosstalk being the electrical goal).

lewm7,338 posts11-22-2019 2:03pm

If you have a pivoted tonearm with headshell offset, and if you then alter azimuth by rotating the arm wand back near the pivot (BEFORE the headshell offset angle is introduced), then the headshell itself not only rotates in the vertical plane described by azimuth but it also changes angle in a second plane which would alter the horizontal.

Perhaps it’s because I’ve never used a pickup arm that adjusts azimuth with the arm wand that I’m having such trouble understanding this. In particular, I don’t see how offset affects this angle, but maybe that isn’t what you meant to say.

If you rotate the arm wand, it seems to me the phono cartridge should ideally only be moving in one plane. If it’s moving in more than one plane, that suggests some error in either the pickup arm geometry itself and/or the arm’s manufacturing tolerances. Normally, zenith would be adjusted by simply rotating the cartridge within the headshell, no?

If when you rotate your arm wand to set azimuth it also alters the zenith of the phono cartridge, how do you then adjust the zenith (after setting azimuth) to the correct angle?