Alignment Calculator
A pivoted arm swings on an arc, so the stylus can only sit tangent to the groove at two radii, the null points. Everywhere else it sits at a small angle to the groove, and that angle is what alignment schemes argue about. Enter your arm's three geometry figures and this plots the error across the record, finds your null points, and works out what Baerwald, Löfgren B and Stevenson would ask of the same arm.
The standard alignments, for your mounting distance
| Alignment | Null points | Overhang | Offset | Max error | Protractor |
|---|---|---|---|---|---|
| Your arm | 65.6 / 120.8 | 12.5 mm | 16.75° | 1.29° | |
| Baerwald (Löfgren A) | 66.0 / 120.9 | 12.57 mm | 16.79° | 1.28° | Protractor → |
| Löfgren B | 70.3 / 116.6 | 12.91 mm | 16.77° | 1.42° | Protractor → |
| Stevenson | 60.3 / 117.4 | 11.19 mm | 16.01° | 1.56° | Protractor → |
Overhang and offset shown for each alignment are what this arm would need at its 311 mm mounting distance.
The three standards are different answers to the same trade, because the error can be moved around the record but never removed. Baerwald levels the distortion peaks across the record, Löfgren B lowers the average at the cost of the extremes, and Stevenson protects the inner grooves, where the music is most crowded, by giving away accuracy everywhere else. The numbers here agree with any accurately printed Baerwald protractor. You can print one from the table above, drawn as an arc for your own mounting distance, so the stylus should follow the printed line right across the record. Read the calibration scales on it before you trust it: a home printer that quietly rescales by 2 per cent makes a protractor worse than none, which is why the sheet carries its own check.
Check the arm and cartridge match too with the resonance calculator →
Who makes these
Bool Audio is a father and son making hi-fi components in a small UK workshop. We build the Clear Wave unipivot tonearm and the Clear Wave 2.0 tonearm cable, both for the Linn LP12. These calculators began as our own bench arithmetic. They are free to use, there is nothing to install, and they take no view on which cartridge you should own.