Mofi Electronics UltraTracker MM

Three moving-magnet cartridges make up the MoFi Electronics Tracker range, all developed with Allen Perkins, founder of Spiral Groove. The UltraTracker sits in the middle position, between the entry-level StudioTracker and the MasterTracker. Compared with its little sister, it gains a machined aluminum body, a nude elliptical diamond, and extended frequency response up to 25 kHz. A clear qualitative step up, without crossing into moving-coil cartridge territory.

A generator modeled on the cutting head

The design principle behind MoFi cartridges is based on a simple idea: reproducing the geometry of the cutting head used in the studio to cut the grooves of a vinyl record. The UltraTracker’s V-Twin generator uses two lightweight magnets arranged in a V, aligned parallel to the stereo grooves. This symmetrical arrangement promotes good channel separation and stable groove tracking, including in the most heavily modulated passages.

The 3.5 mV output voltage is sufficient to drive any standard MM phono preamplifier, with a recommended load impedance of 47 kΩ and capacitance of 100 pF. On this last point, the capacitance of the cable linking the tonearm and the preamplifier must be taken into account: a cable with too much capacitance could alter the high-frequency response.

Machined aluminum body: mass and damping

The most visible difference between the StudioTracker and the UltraTracker lies in the body material. The StudioTracker uses a polymer housing treated with a proprietary damping material. The UltraTracker moves to a solid billet-machined aluminum block, significantly heavier: 9.7 g versus 6.4 g for the StudioTracker.

This choice has direct consequences on mechanical behavior. Solid aluminum offers greater rigidity and better control of parasitic resonances. The bass gains grip and definition, and the stereo image appears sharper. The higher weight does, however, require checking compatibility with the tonearm: most modern medium- to high-mass tonearms accept a cartridge of this size without difficulty, but a very light tonearm could pose a resonance problem.

The mounting holes are threaded, which simplifies installation on the headshell compared with the StudioTracker and its nuts that must be screwed on from underneath.

Nude elliptical diamond and groove tracking

The UltraTracker is equipped with a nude elliptical diamond. “Nude” means the diamond tip is bonded directly to the cantilever, without an intermediate shank. This construction reduces the moving mass at the end of the cantilever, which improves tracking ability during fast transients and heavily modulated passages.

The elliptical profile reads a wider contact surface in the groove than a spherical (conical) tip, making it possible to extract more engraved information, with less distortion in the high frequencies. The stated frequency response extends from 20 Hz to 25 kHz, which is 5 kHz more than the StudioTracker, which tops out at 20 kHz.

The recommended tracking force is between 1.8 and 2.2 g. A setting around 1.9 to 2.0 g is a good starting point, to then be adjusted by ear depending on the tonearm and turntable.

Manufacturing between Japan and the United States

Assembly of the Tracker cartridges is carried out by hand in Japan. The UltraTracker’s aluminum body is machined in the United States, in MoFi’s workshops in Michigan. Allen Perkins supervised the damping work and acoustic tuning, with careful attention paid to reducing internal resonances.

Like all cartridges in the Tracker range, the UltraTracker does not have a user-replaceable diamond. When the stylus is worn, the entire cartridge must be replaced. MoFi offers a reduced-price exchange program to offset this drawback. This design choice, shared with Rega in this price range, is intended to guarantee optimal and permanent alignment between the diamond, the cantilever, and the generator.

Sound reproduction and musical character

Compared with the StudioTracker, the UltraTracker delivers a more open and more detailed sound. The StudioTracker has a slightly warm and forgiving side, with a somewhat rounded treble and generous bass. The UltraTracker tightens up the low end: the bass is tauter, better defined, without the slight roundness of its junior sibling. The midrange gains articulation and the treble, more extended, reveals information that the StudioTracker leaves in the shadows.

Dynamics also improve, thanks to the combination of the rigid aluminum body and the low-mass nude diamond. Micro-variations in intensity are reproduced better, resulting in a livelier presentation on acoustic recordings and carefully made productions. On heavily modulated records (rock, symphonic music), groove tracking remains stable and free from perceptible distortion even in the densest passages.

The sonic character remains musical rather than clinical. The UltraTracker is not a cold or analytical cartridge: it retains body and density in the timbres, while gaining transparency compared with the StudioTracker.

Compatibility and setup

The UltraTracker mounts on any tonearm that accepts a standard-mount cartridge (half-inch). At 9.7 g, it is suitable for medium-mass tonearms, which make up the vast majority of the market. MoFi tonearms (Studio and Ultra, in 10 inches) are obviously designed to accommodate it, with vertical tracking angle (VTA) and azimuth pre-set at the factory when the cartridge is purchased with a MoFi turntable.

On a third-party tonearm, the usual adjustments will be required: stylus alignment (Baerwald or Stevenson protractor depending on the tonearm geometry), tracking force, anti-skating, and VTA. The integrated threads make the operation easier.

Technical specifications

Electrical and mechanical specifications

• Type: Stereo dual-magnet Moving Magnet (MM)
• Output voltage: 3.5 mV
• Frequency response: 20 Hz – 25 kHz
• Impedance: 47 kΩ
• Recommended capacitance: 100 pF
• Weight: 9.7 g

Stylus and tracking

• Stylus type: nude elliptical
• Recommended tracking force: 1.8 – 2.2 g
• Advantages:
  • Excellent tracking of complex passages
  • Better reproduction of micro-details
  • Reduced distortion in the high frequencies

Key technologies

• V-Twin dual-magnet generator
  • Two lightweight magnets in a V configuration
  • Aligned with the stereo grooves
  • Precise reading of the recorded signal
  • Better channel separation
  • Improved dynamics
  • More stable groove tracking
• Machined solid aluminum body
  • Billet aluminum structure
  • Damping of internal vibrations
  • Precise resonance control
  • Tighter bass
  • Cleaner sound image

Sound signature

• More open and detailed sound than the StudioTracker
• Tight, precise bass
• Rich, well-defined mids
• Extended highs up to 25 kHz
• Excellent dynamics and micro-information

Recommended users and uses

• Advanced entry-level audiophiles
• Upgrade from standard MM cartridges
• Demanding yet versatile hi-fi systems
• Analytical and musical listening

General information

The UltraTracker sits above the StudioTracker, offering higher resolution, better dynamics, and a more rigid construction, while remaining within the accessible Moving Magnet universe.