Reed 5T Opinions

I think you could do zenith with a regular USB by first aligning the cantilever horizontally or vertically in the field of view, and then changing the focus to look for the contact edge.  It would be even easier if the USB is capable of taking multiple images at different focal points and then integrating the images to get something that has a good depth of field, but, those scopes are about $1500 or more.  If you know the alignment of the cantilever, even if you cannot see it, you can see the stylus orientation and that would give you some idea about the zenith error.  I am sure an even fancier scope, would make this easier.

I sort of prefer not really knowing all of these things.  While I have a Fozgometer, I don't really use it that much.  I prefer to align the stylus visually to be perpendicular to the record surface.  If this is not electrically ideal with regard to crosstalk, I still rather do my records the kindness of having the stylus fit the groove properly.  VTA/SRA I set by leveling the cartridge and then listening to changes in the angle to find the right spot.  Basic alignment I do with a Smartractor.  This is more or less good enough for me.  I think record playing is robust enough to survive even rough alignment.

Mijo, if you re-read my post I did qualify my remark about skating force with the phrase “in a conventional pivoted tonearm”, which the 5T, 5A, LT, Thales, etc, are not.

This bit about zenith is fun, and it probably does show us another way in which vinyl is flawed. Now I will go back to ignoring it and enjoying the music. For a perfectly constructed cartridge in a perfect conventional overhung pivoted tonearm, zenith can be perfect for only two brief moments, at each of the two null points. Zenith is a correllary of tangency. For those who really want to fret about zenith, the only solution is a perfectly set up linear tracking tonearm. I don’t own one of those. The definition of zenith that I am using is: correct zenith occurs when a line drawn from one contact point through the other contact point on the stylus tip,if extended will pass through the center of the spindle. And, by the way, even a perfectly set up linear tracker won't get you to perfect zenith, if the stylus was not mounted square with the cantilever, and if the cantilever is not perfectly straight. (Well, to some degree you can correct for a bent cantilever by twisting the cartridge body.)

lewn,

True, even with perfect zenith alignment, only at the null point would the contact area of the cartridge along the line of tangency.  But, the maximum error at other points will still be relatively small, whereas, zenith error in manufacturer is much higher, typically, according to the Wallytools people, plus or minus five degrees.  Still, I am not inclined to open that can of worms with my setup.

mijostyn,

The dramatic difference in the inertial mass of air-bearing arms in the horizontal and vertical planes may be a problem or it may be a benefit.  There are some arms, like the Morch Anisotropic arm, that deliberately increases the horizontal mass by using outrigger weights on the vertical axis (to reduce impact on vertical mass) so that the arm resists swinging side to side when large horizontal groove movements (i.e., monophonic bass waves) are presented.  This preserves such bass information (a lot of deep bass is recorded monophonically (side to side movement) in order to reduce big changes in depth of the groove that stereophonic  recording would entail),  I've heard that arm and it DOES have impressive bass response.  Likewise, I've heard impressive bass response from air-bearing arms, like the ET-2, and the high horizontal effective mass might be the reason.  But, I do worry about whether such arms put a lot of strain on the cantilever when it has to drag the whole setup across the record--not only is the mass high, the lack of mechanical advantage of a pivot means a lot of force is needed to drag that arm linearly.  This high sideways resistance to movement also makes we wonder if that means the cantilever is never tangent to the groove.  Still, I've heard nice sound from all types of arms, so I don't know if any are inherently superior.

Larry, Reports from my friend who has taken up a formal study of zenith error tend to agree with yours, to the effect that cartridge manufacturing errors are paramount in determining the error.

Also, I agree with your point about inertial mass of linear trackers (air bearing or otherwise). Some reputable engineers evidently think that high inertia in the horizontal plane is desirable for best bass frequency reproduction. Not only do we see some pivoted arms like the Moerch with outrigger weights at the horizontal pivot but also we have the Dynavector tonearms which very deliberately also strive for high horizontal effective mass. I have mentioned this at least once before, but one rationale for that goal arises if you consider that bass frequencies, increasingly as f goes down, are generated by increasingly horizontal motion of the stylus tip. Since these frequencies generate a lot of energy at the stylus/cantilever, the high inertial mass would be seen to stabilize the pivot relative to the stylus tip, so that the tail does not wag the dog (from side to side). Fremer often repeats his bias view that horizontal and vertical effective mass ought to be nearly equal, and, right or wrong, his opinions have had an effect on others’ perceptions. I suppose he learned his opinion at the feet of one or another tonearm designer who feels the two should be about equal. But I have never heard or read a good argument for it.