Mofi Electronics UltraDeck + UG

When Mobile Fidelity Sound Lab, the legendary label founded in 1977, decided to make its own turntables, it turned to Allen Perkins, the designer of Spiral Groove turntables (models sold for up to $36,000). The result, the UltraDeck, is made in the United States at MoFi’s factory in Ann Arbor, Michigan. The + UG version comes ready to use with the UltraGold moving coil (MC) cartridge factory-mounted and aligned.

A chassis designed for silence

The UltraDeck weighs about 10.5 kg, and that weight is no accident: mass contributes to mechanical stability and the damping of unwanted vibrations. The plinth is built with a multilayer construction in which three aluminum plates are bonded to an MDF body (versus just one plate on the lower model, the StudioDeck). This technique, known as “constrained layer damping,” takes advantage of the different vibrational properties of aluminum and MDF to dissipate resonances instead of transmitting them to the stylus.

The anti-vibration feet were developed with Harmonic Resolution Systems (HRS), a manufacturer specializing in audio equipment isolation. Each of the four feet is independently adjustable, making it easier to level the turntable, an essential step for proper playback.

A 33 mm thick Delrin platter

The 3.1 kg platter is machined from a block of Delrin, a crystalline polymer developed by DuPont. This material is chosen for a specific reason: its mechanical impedance is close to that of vinyl, allowing vibrations from the record to be drained into the platter rather than reflected back to the stylus. The UltraDeck platter is 75% thicker than the StudioDeck’s (33 mm versus 19 mm), resulting in greater inertia and lower background noise.

The inverted bearing combines hardened steel, bronze, and sapphire, a combination of materials usually found on much more expensive turntables. The ester-based grease used in the bearing also contributes to quiet rotation.

Belt drive and synchronous AC motor

The motor runs at 300 rpm and drives the platter via a belt using a two-step Delrin® pulley, one for 33 ⅓ rpm and the other for 45 rpm. Speed change is done manually by moving the belt from one step to the other, without having to remove the platter (unlike some competing turntables in this range).

The synchronous AC motor provides high speed stability, with wow and flutter measured between 0.017% and 0.025%, and a signal-to-noise ratio of 74 dB. An important point: the motor is mechanically decoupled from the chassis by damping materials, preventing its vibrations from traveling up to the stylus. Power consumption remains modest, below 5 W.

The 10-inch Ultra Tonearm

The tonearm, developed by MoFi and made in the United States, measures 10 inches (254 mm). It is an intermediate format between standard 9-inch tonearms and the 12-inch tonearms of high-end turntables: it reduces tracking error compared with a 9-inch tonearm, while remaining compatible with a compact chassis.

Construction is aluminum, with high-precision ball bearings that ensure low friction in both the horizontal and vertical planes. The internal wiring is by Cardas Audio, from the headshell leads to the gold-plated RCA connectors protected by copper shielding against RF interference. Available adjustments are comprehensive: tracking force, vertical tracking angle (VTA), azimuth, and anti-skating. If you order the turntable with a preinstalled MoFi cartridge, the VTA and azimuth are factory-set, which simplifies setup.

The UltraGold MC cartridge, made in Japan

This is the cartridge that sets this + UG version apart from the other UltraDeck variants. The UltraGold is a moving coil (MC) cartridge made in Japan under strict quality control, then adjusted by Allen Perkins. It uses a nude Shibata stylus mounted on a boron cantilever, a combination rarely found at this price level. The magnet is made of neodymium, with a permendur yoke (an iron-cobalt alloy with high magnetic permeability), all housed in a hybrid aluminum-brass body designed to minimize vibrations.

A few technical data points: output voltage of 0.4 mV, frequency response from 20 Hz to 35,000 Hz, recommended tracking force between 1.8 and 2.2 g, recommended load of 100 ohms minimum. The cartridge weighs 7.3 g, well within the Ultra Tonearm’s compatibility range (5 to 10 g). The threaded body allows mounting with two screws, without nuts, making installation quick if you ever need to replace the cartridge.

Compared with MoFi moving magnet cartridges (the MasterTracker and UltraTracker), the UltraGold MC offers a higher level of resolution in micro-detail, a wider and deeper soundstage, and more pronounced dynamics. It is the logical choice if your hi-fi system is capable of revealing these differences, provided you have an MC-compatible phono preamplifier with a load of at least 100 ohms.

What you need to know before buying

The UltraDeck + UG comes with a smoked dust cover, a power cord with IEC connector (replaceable with an audiophile cable if desired), and the UltraGold MC cartridge already mounted. Final assembly is limited to placing the platter, installing the belt and counterweight, then leveling the turntable.

A few points to keep in mind: the UltraGold MC cartridge has a low output voltage (0.4 mV) and requires an MC phono preamplifier. An MM-only preamplifier will not be suitable. MoFi offers its own preamplifiers (UltraPhono and StudioPhono) with MC input and adjustable loading, but any quality MC preamplifier will do. The optional MoFi Super HeavyWeight record weight (about 370 g) is not included but can improve record-to-platter contact, especially on slightly warped records.

Technical Specifications

Motor and Drive

• Motor: AC synchronous 300 RPM
• AC motor isolated from the chassis
  • Rotational stability
  • Reduction of mechanical vibrations
  • Increased rhythmic precision
• Speeds: 33 ⅓ and 45 RPM (belt drive)
• Power consumption: < 5 W

Platter

• 1.3” Delrin platter (≈ 33 mm) – 3.1 kg
  • High inertia
  • Blacker background
  • Stable and silent playback

Audio Performance

• Wow & flutter: 0.017% – 0.025%
• Signal-to-noise ratio: 74 dB

Tonearm

• 10” Ultra Tonearm (aluminum), made in the USA
• High-precision ball bearings
• Cardas Audio internal wiring
• Gold-plated RCA connectors
• Overhang: 18 mm
• Offset angle: 22.8° (± 2° adjustable)
• Compatible cartridges: 5 g – 10 g
• Optimal signal transmission

Included Cartridge

• UltraGold MC cartridge (Moving Coil)
• Factory-optimized alignment
• Higher resolution level than the +M version
• Finer, more dynamic, and more airy reproduction
• Increased micro-detail resolution
• Wider and deeper soundstage
• Improved dynamics

Chassis and Isolation

• Anti-resonance multilayer structure (Constrained Layer Dampening)
  • Aluminum and multilayer MDF
  • Elimination of resonances
  • Sonic neutrality
  • Faithful signal reproduction
• High-performance HRS isolation, developed with Harmonic Resolution Systems
  • Decoupling from the floor
  • Reduction of unwanted vibrations

Dimensions and Weight

• Dimensions (W × H × D): 50.0 × 15.2 × 36.2 cm
• Weight: 10.5 kg

Highlights

• High-end version with UltraGold MC cartridge
• Improved resolution and dynamics
• High-mass Delrin platter
• 10” Ultra Tonearm made in the USA
• AC motor isolated from the chassis
• Very low background noise

Sound Signature

• Very high resolution
• Holographic soundstage
• Deep, controlled bass
• Ultra-detailed mids
• Extended, airy highs
• Excellent instrument separation