Calculate the effective tonearm mass


I don't know the effective mass of my tonearm!.

Well. that happens quite often. Either the effective mass of a tonearm is not given by the manufacturer, or one has a homemade tonearm or a modified arm. So how can you correctly calculate the effective mass of the tonearm?
A commonly used method that is recommended is to weigh the arm without element and without counterweight. You need a digital stylus weigher for this and then weigh the tonearm + headshell at the point where the stylus is. It gives a very rough value of the effective tonearm mass. But understand that this is not the right way.

There are many more factors that determine the effective mass of the tonearm and it takes a fair amount of mathematical insight to work out these calculations to arrive at a real effective tonearm mass.

The main factors that determine the effective mass of the tonearm system + cartridge are:

  1. the distance from arm bearing to center of counterweight (D)
  2. the tonearm length from arm bearing to needle (L)
  3. weight of the cartridge + mounting material (CF)
  4. the recommended stylus pressure of the element (V)

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