The Pro-Ject 107g Counterweight (031) is a precision-machined replacement or upgrade counterweight designed for Pro-Ject tonearms that use the 031 counterweight series. Fitting the counterweight correctly is essential for achieving accurate and consistent vertical tracking force, which directly affects how well your cartridge traces the groove and the quality of sound you extract from your records.
What the 031 Designation Means
Pro-Ject uses a numerical code to identify counterweight compatibility with specific tonearm models. The 031 code refers to the counterweight mount and thread specification used on a range of Pro-Ject 9-inch tonearms, including the 9cc Evolution and related derivatives. This 107g version is suited to cartridges with a moderately high recommended tracking force, typically between approximately 1.5g and 3.5g VTF, depending on the cartridge body mass.
Correct Tracking Force
Installing the correct counterweight is the first step towards setting your tonearm for optimal performance. An incorrectly weighted counterweight may make it impossible to set the tracking force within the manufacturer-recommended range, leading to poor tracking, distortion, or accelerated record and stylus wear. The 107g mass gives sufficient range for many popular mid-to-high compliance cartridges.
Installation
The counterweight threads directly onto the rear stub of the compatible Pro-Ject tonearm. After fitting, zero the tracking force gauge by balancing the arm parallel to the platter, then rotate the tracking force dial to your cartridge-specified value.