Cartridge Alignment Using the 2.60 and 4.76 Positions

Discussion in 'Audio Hardware' started by ShockControl, Mar 27, 2017.

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  1. ShockControl

    ShockControl Bon Vivant and Raconteur! Thread Starter

    Location:
    Lotus Land
    I am continuing a conversation that I began offline with action pact.

    I am aligning a cartridge using a mirrored protractor tool that fits over the turntable spindle.

    It seems to me that a great deal of this is based on eyeballing and that it is not that exact of a science.

    First, to even see when the stylus's reflection is above point A and point B, you are seeing it from a slight a angle (unless every component of the headshell is entirely clear). I am able to see when the cantilever is generally aligned with the target line, but it seems like it would be very easy for it to be microscopically off without visible detection.

    My second question has to do with the grid lines for the cartridge body. Is it even worth considering this if you are aligning by the cantilever reflection? How do we know that the cartridge body is symmetrical? Also, logic would suggest that no two points can ever exactly line up flush against the gridlines, because the tone arm pivots, ultimately creating a soft curve and not a straight line.

    Am I worrying too much about this? What are your thoughts?
     
  2. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    Cartridge body can help you get close, but the cantilever is the thing.

    Also, you might find an arc protractor gives you a higher degree of precision in that the overhang will be verifiable at any point and there is less room for visual aberration. Often the cantilever is such that the cartridge body will be a bit askew when the cantilever is right on.

    In my experience, a tight alignment with an arc protractor always looks spot on with a two-point. However, a two-point alignment can look pretty good, but an arc protractor will expose the error in overhang. That said, a two point mirror is very good for azimuth and getting the cantilever aligned.
     
  3. sunrayjack

    sunrayjack Forum Resident

    I watched an audiophile all this tonight, all I can say is it was interesting to watch.
    I'm sure it has some merit in getting things aligned properly.
    I am more a CD guy, wipe it on my shirt and put it in and enjoy the music.
     
    timind, dcottrell6 and The Pinhead like this.
  4. ShockControl

    ShockControl Bon Vivant and Raconteur! Thread Starter

    Location:
    Lotus Land
    Thanks. I still don't understand, though, how it can perfectly align in both locations, when the protractor shows all lines with right angles, and the tone arm produces a curve. I guess the idea is to get it as close as reasonably possible?
     
  5. Jimi Floyd

    Jimi Floyd Forum Resident

    Location:
    Pisa, Italy
    In theory, the tonearm should be exactly aligned in both positions. Think to the arm going a curved line, while the "exact" tracking would be a straight line. There are two points (Q' and Q in the following picture, which is a simplified example!) where the curve and the horizontal both have the same zero (tracking error) value.

    [​IMG]
     
  6. ShockControl

    ShockControl Bon Vivant and Raconteur! Thread Starter

    Location:
    Lotus Land
    So this is based on the idea that there are straight lines from the center of the circle to perimeter. That makes sense.

    Do you concur that the most important aspect is getting the cantilever is aligned in both positions?
     
  7. jupiterboy

    jupiterboy Forum Residue

    Location:
    Buffalo, NY
    Exactly, and you can look at, for instance, inner and outer dimensions for the groove, and mitigate the overall and and peak distortion in exchange for less distortion toward the label, for those records that pack more onto a side. You are always aligning to be perfectly on with two points on the arc.

    It that's not good enough, there are longer tonearms and linear trackers.
     
  8. John Buchanan

    John Buchanan I'm just a headphone kind of fellow. Stax Sigma

    The different alignments relate to what radius the 2 zero points are set at. One alignment tries to make the minimum recorded radius one of the zero points at the expense of increased tracking error at the lead-in grooves; another makes an argument for minimum distortion across the whole record, and zero points are at radii inside the recorded areas. It's all interesting reading up to a point.
    The longer tonearm comes at an expense of increased tonearm mass - OK when you have a low compliance moving coil cartridge, but not a great solution if using a high compliance cartridge.
    Tangential trackers have their own problems (mechanical complexity being one), but I still lust after a B & O 4000 or 6000 turntable - a thing of beauty.
     
  9. H8SLKC

    H8SLKC Forum Resident

    Location:
    Boston, MA
    It's an oxymoron that while analog fans worry greatly about precision regarding cart/cantilever alignment, the very records themselves are almost always jacked up. They are rarely centered on the spindle hole, they are wavey, warped, and here we get extremely worried about the precision of turntables, arms and cartridges! In full knowledge of these ironies, I find myself drawn to analog...
     
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