Turntable Tonearms

The role of the tonearm in the playback chain

The tonearm forms the mechanical link between the turntable and the phono cartridge. Its job is to keep the cartridge in optimal conditions to read the record grooves: correct angle, appropriate tracking force, maximum stability. A quality tonearm must be both rigid, to avoid transmitting unwanted vibrations to the cartridge, and light, to minimize inertia that could hinder groove tracking. These two seemingly contradictory requirements explain why the choice of materials and the arm’s design directly influence the sonic result.

The tonearm must also allow the user to mount, adjust, and change the cartridge as needed. Three mounting systems coexist: P-Mount (simplified direct connection), Standard (screw mounting on a headshell), and Ortofon/SME (a modular system that facilitates quick cartridge changes). This mechanical compatibility between arm and cartridge determines the possible upgrades for the turntable.

The different types of tonearms

The gimbal arm is the most common type. Equipped with two bearings allowing horizontal and vertical movements, it offers a good compromise between effectiveness, ease of adjustment, and manufacturing cost. Friction forces are still present in both bearings, which can generate unwanted vibrations and slight distortion. Entry-level arms generally use metal alloys, while higher-end models favor aluminum or carbon fiber for their rigidity and low mass.

The unipivot arm uses only a single joint instead of two. Balanced on a single pivot (sometimes ruby or resting in a silicone gel bath), it minimizes friction and offers total freedom of movement that allows the cartridge to follow the groove with great precision. However, this design requires meticulous azimuth adjustment, since the arm can pivot in all directions. More delicate to set up and generally more fragile, the unipivot arm remains appreciated by audiophiles for its musicality.

The tangential arm replicates the motion of the cutting stylus that engraves master discs. It moves linearly, perpendicular to the groove, keeping the stylus constantly aligned at the ideal playback angle. This design theoretically eliminates tracking error and drastically reduces distortion. This type of arm is found mainly on high-end turntables due to the complexity of its servo mechanism. Some models use air suspension to ensure frictionless movement. Technics, Marantz, Revox, and B&O turntables from the 70s–80s offered tangential arms, models that are now sought after on the second-hand market.

Arm length and geometry

9-inch arms (about 23 cm) equip most turntables. This standard length is the result of a compromise between tracking error (which decreases with length) and the turntable’s footprint. 12-inch (30 cm) arms reduce the angular offset between the stylus position and the ideal cutting axis. Certain esoteric turntables from brands like Transrotor, Thorens, Clearaudio, or Pro-Ject accept 12-inch arms in place of standard arms, offering an upgrade path.

The arm’s shape (straight or S-shaped) doesn’t affect tracking error but influences other parameters. A straight arm theoretically offers better rigidity thanks to its monobloc structure, while an S- or J-shaped arm helps compensate for tracking error on compact or DJ turntables where space is limited. However, the additional angles of a curved arm create variations in material density that can favor resonance phenomena.

Tonearm adjustments and parameters

The counterweight at the rear of the arm allows adjustment of the tracking force exerted by the cartridge on the record. This setting, expressed in grams, must follow the cartridge manufacturer’s recommendations to avoid premature wear of the stylus or groove. Prior balancing of the arm (position where it floats horizontally) is the starting point before any tracking force adjustment.

Antiskating compensates for the centripetal force that naturally pulls the arm toward the center of the record during playback. This parameter, generally set to the same value as the tracking force, prevents unbalanced pressure on the groove walls and premature stylus wear. Adjustment is done via a graduated dial, magnet, or counterweight depending on the model.

VTA (Vertical Tracking Angle) defines the angle formed by the cartridge’s cantilever with the record surface. Azimuth corresponds to the cartridge’s lateral tilt relative to the plane of the record. These fine adjustments, available on high-end arms, optimize stereo channel separation and minimize distortion. A spirit level, a test record, and a stylus force gauge make these precision adjustments easier.

Replacing your turntable’s tonearm

Replacing the tonearm is a significant upgrade to optimize a turntable’s performance. This operation requires checking the compatibility of the armboard mounting hole and observing the specified distance between the platter’s center axis and the arm’s pivot point, as specified by each manufacturer. Brands such as Rega, Pro-Ject, Ortofon, Thorens, or SME offer replacement or additional arms, from midrange to audiophile references.