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Re: Absolute cartridge mounting method....(very industrial and non-audiophile)

Hi, Busybusy

You are partly right: I'm not qualified to comment on your specific practical method in measuring the overhang (exactness, etc), but some variety of this method can be used as an equivalent to the one-point gauge that comes with many tonearms, like Linn and Rega (except that these gauges also check the mounting of the tonearm). For instance, one could use a device (designed with the shape and geometry of the particular arm in question in mind) to measure the distance between the front of the headshell and the stylus tip.

HOWEVER:

The method presupposes a specific mounting distance of the tonearm (the spindle--tonearm-pivot distance). In cases like a Linn arm on a Linn table, we must assume that the factory hasn't made any severe mistakes in drilling the hole for the tonearm. In this case, the correct OFFSET ANGLE will be obtained when the cartridge, or cantilever, is parallell to the sides of the headshell and you stick to the overhang in the specs. (I assume that the cartridge will indeed be parallell to the headshell when the tonearm specs are followed.) This point must be included in the method; then you can use it. Note, incidentally, that your choice in geometrical approach is limited.

Things become more complicated if the mounting distance of the arm differs from the one implied by the specs, which can happen if you use, say, a Linn arm on a non-Linn table with a fixed mounting position for the arm. You will need a template to set the offset angle, and the overhang is not easy, either, although it can be measured. If you follow the tonearm specification of 18mm in this case, the effective length (overhang plus mounting distance) will be different than assumed by the specs, and for different effective lengths, there are different optimal overhangs and offset angles. So 18mm may not longer be the desired overhang!

Actually, a traditional method is to measure the effective length (difficult), then calculate and measure the overhang, then go back to check the effective length, etc. When you finally is ready and overhang is set, you use a template to get the offset angle right at one point, being careful not to move the stylus tip out of its position, only the cantilever. This method (still in use) is described in practical terms in cartridge setup link no. 10b in the FAQ and is summed up in the chapter "Prior alignment methods" in link no. 9.

If you are able to position the tonearm where you want it, for instance by way of a movable arm board, you can measure the distance between the tonearm pivot and the spindle (which is often very diffult), follow the tonearm specs in this regard (mounting distance = effective length minus overhang), and then perform your routine.



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