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Bought a turntable: Aligning a cartridge once again

New (old) Technics SL1200 Turntable





I picked up a Technics SL1200 yesterday - wanted a turntable that was portable.

So I dug out this old piece of mine from the archives.

The text is a bit too verbose, but the method works. The method is based on the approximate 50% relationship between the inner and outer null radii.
This produces the relationship that when the cartridge is adjusted 1mm forwards on the inner grid of a protractor, the angle changes by about twice as much when compared to the same adjustment on the outer grid.

E.G. 1mm forwards on the inner grid produces the same angular change as 2mm on the outer grid.

The method is pasted below - and there is also a link to the original article.

It takes about two iterations (outer grid then inner grid) to get the cartridge correctly aligned.





Setting Cartridge alignment using a Two Point Protractor

Method.


1. Set the cartridge, so that its fixing bolts are roughly in the centre of the head-shell slots.

2. Place the protractor over the platter spindle.

3. Position the stylus on the outer alignment point ( at the centre of the outer grid at 120.9mm).

4. Adjust the angle of the cartridge in the head-shell until the cartridge is squared up on the grid. The cantilever should be parallel to the centre line on the grid.

5. Move the tone-arm so that the stylus is at the centre of the inner alignment point (inner grid at 66.0 mm). It is necessary to rotate the protractor about the spindle to do this. If the cartridge is squared up with the grid, then the alignment is complete. However, if the cartridge is not squared up with the inner grid, then determine which direction the cartridge should be rotated (when viewed from above) in order to achieve alignment on the inner grid. Do not make any adjustment at this point. Case 1: if correct alignment requires an anti-clockwise rotation of the cartridge, then the effective length is too short. Case 2: if correct alignment requires a clockwise rotation of the cartridge, then the effective length is too long.

6.
Case 1:

Increase the effective length of the arm, by sliding the cartridge forwards in the head-shell. The correct effective length can be set by sliding the cartridge forwards by twice the apparent correction necessary to align the cartridge on the inner grid. For example, if sliding the cartridge forward by 1mm in the head-shell, will give alignment on the inner grid, then the correct adjustment is to slide the cartridge forwards by 2mm. If possible do not adjust the angle of the cartridge in the head-shell while adjusting the effective length. After completing this step, the tracking error should be about the same as before, but with the cartridge skewed in the opposite direction.

Case 2:

Decrease the effective length of the arm, by sliding the cartridge backwards in the head-shell. The correct effective length can be set by sliding the cartridge backwards by twice the apparent correction required to align the cartridge on the inner grid. For example if sliding the cartridge back by 1mm, gives alignment on the inner grid, then the correct adjustment, is to slide the cartridge backwards by 2mm. If possible do not adjust the angle of the cartridge in the head-shell while adjusting the effective length. After completing this step, the tracking error should be about the same as before, but with the cartridge skewed in the opposite direction.

7. Move the tone-arm back and reposition the protractor, so that the stylus falls on the outer alignment grid. Adjust the angle of the cartridge again so that the cartridge is squared up on the grid.

8. Repeat steps 5, 6 and 7 until alignment is achieved at both points.

Mirrored Protractor with grids at 2.60'' and 4.76''








Edits: 04/15/17 04/15/17

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Topic - Bought a turntable: Aligning a cartridge once again - B.K. 12:27:03 04/15/17 (0)

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