Tonearm Register
Effective mass and mounting geometry for the arms our calculators know about, taken from the makers' own specification sheets wherever one exists, with a source recorded for every figure. Effective mass is the figure a resonance calculation needs and the one hardest to find — most arms never publish it, and the ones that do rarely say which configuration it applies to.
Open the resonance calculator → Download the register (CSV) ↓
What the columns mean: Effective mass ? Pivot to spindle ? Offset angle ?
Bool Audio
| Tonearm | Bearing | Pivot to spindle | Effective mass | Offset angle |
|---|---|---|---|---|
| Clear Wave | Unipivot | 211 mm | 11 g | 24.00° |
| Clear Wave (with ceramic spacer) | Unipivot | 211 mm | 13 g | 24.00° |
Linn
| Tonearm | Bearing | Pivot to spindle | Effective mass | Offset angle |
|---|---|---|---|---|
| Akito | Gimbal | 211 mm | 10 g | ~24.08°, derived from the effective length |
| Ekos | Gimbal | 211 mm | 11.5 g | ~24.08°, derived from the effective length |
| Ekos SE | Gimbal | 211 mm | 11.5 g | ~24.08°, derived from the effective length |
| Ittok LVII | Gimbal | 211 mm | 11.5 g | ~24.08°, derived from the effective length |
Naim
| Tonearm | Bearing | Pivot to spindle | Effective mass | Offset angle |
|---|---|---|---|---|
| ARO | Unipivot | 212.5 mm | 11 g | ~23.92°, derived from the effective length |
Ortofon
| Tonearm | Bearing | Pivot to spindle | Effective mass | Offset angle |
|---|---|---|---|---|
| AS-212R (with LH-9000 headshell) | Gimbal | 214 mm | 23.8 g | 23.75° |
| AS-212R (without headshell) | Gimbal | 214 mm | 7 g | 23.75° |
| AS-309R (with LH-9000 headshell) | Gimbal | 311 mm | 27.8 g | 16.75° |
| AS-309R (without headshell) | Gimbal | 311 mm | 11 g | 16.75° |
Rega
| Tonearm | Bearing | Pivot to spindle | Effective mass | Offset angle |
|---|---|---|---|---|
| RB300 | Gimbal | 222 mm | 11.5 g | 23.00° |
| RB330 | Gimbal | 222 mm | 11 g | 21.55° |
SME
| Tonearm | Bearing | Pivot to spindle | Effective mass | Offset angle |
|---|---|---|---|---|
| Series V | Gimbal | 215.35 mm | 10.5 g | 23.64° |
Figures are as published. Where a maker sells an arm in more than one configuration — a detachable headshell, a different counterweight — each is listed separately, because those change the effective mass by more than a resonance calculation can absorb. Offset angles are shown as published where a maker states one, and otherwise worked out from the effective length and the alignment geometry the arm follows, which is marked. Spotted an error? Tell us at info@boolaudio.com and we will check it against the source.
The CSV holds the same figures as this page, one row per arm and configuration, with the source for each. Free to use.
Manufacturer and tonearm names are the trademarks of their respective owners. Bool Audio is independent of them all, and none has endorsed this register.
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.