Mofi Electronics UltraDeck + M

When a vinyl pressing label recognized since 1977 for the quality of its reissues decides to manufacture its own turntables, the promise is crystal clear: reproduce the sound exactly as it was cut, without coloration or mechanical compromise. The UltraDeck + M is the most fully realized version in this range, delivered with the MasterTracker cartridge preinstalled and factory-aligned. Designed with Allen Perkins, founder of Spiral Groove, and manufactured in MoFi’s Michigan factory, it weighs 10.5 kg and makes no secret of its ambition: silence.

A 33 mm Delrin platter that changes the noise floor

The UltraDeck platter is machined from a block of Delrin, a crystalline polymer developed by DuPont. In analog hi-fi, this material has a mechanical impedance close to that of vinyl: parasitic vibrations generated by the stylus in the groove are absorbed by the platter instead of being reflected back toward the cartridge. The record sits directly on the Delrin, with no intermediate mat.

At 33 mm thick and 3.1 kg, this platter is 75% thicker than the one on the StudioDeck, MoFi’s entry-level model. The additional mass increases rotational inertia, smoothing out micro-variations in speed and contributing to a very low noise floor. The hardened steel inverted bearing, coupled with a sapphire thrust pad and a bronze bushing, runs in ester-based grease to ensure smooth, silent rotation over the long term.

Multilayer construction: three aluminum plates on an MDF plinth

The UltraDeck chassis is based on a principle known as constrained layer damping: three aluminum plates are bonded to an MDF body. The combination of two materials with different vibrational properties suppresses resonances far more effectively than a single material alone. Aluminum provides rigidity and mass, while MDF absorbs low frequencies. The StudioDeck uses only a single aluminum plate; the UltraDeck triples that number, resulting in greater tonal neutrality and significantly higher overall weight.

The four anti-vibration feet were developed in collaboration with Harmonic Resolution Systems (HRS), a specialist in mechanical isolation for audio equipment. They isolate the turntable from vibrations transmitted by the furniture or the floor, a point often underestimated when setting up a vinyl turntable.

The Ultra Tonearm: 10 inches, Cardas wiring

MoFi manufactures its own tonearm in the United States. It is a straight 10-inch (254 mm) aluminum tonearm mounted on precision ball bearings. The 10-inch length is an interesting compromise between the standard 9-inch format and 12-inch long arms: the arc described by the stylus across the record is gentler than with a 9-inch arm, reducing tracking error, without the space and effective mass constraints of a 12-inch arm.

The internal wiring is handled by Cardas Audio, from the headshell leads all the way to the gold-plated RCA connectors at the rear. These connectors are protected by copper foil shielding against RF interference. The tonearm offers adjustment for tracking force, vertical tracking angle (VTA), azimuth, and anti-skating. On this + M version, the cartridge is preinstalled with all these settings already calibrated: you simply place the platter, fit the belt, and connect the cables to listen.

The tonearm’s effective mass is 25.14 g (± 0.5 g), making it a rather heavy arm. It works with medium- to low-compliance cartridges weighing between 5 and 10 g, a profile that matches MoFi’s MM and MC cartridges.

The MasterTracker cartridge: designed after the cutting head

The MasterTracker is the top-of-the-range cartridge in MoFi’s “Tracker” series. Its body is machined from a block of 6061 aluminum in the United States; final assembly is done by hand in Japan. Allen Perkins supervised its sonic development.

Its operating principle is based on a dual-magnet “V-Twin” generator: two lightweight magnets are arranged in a V, parallel to the record grooves, reproducing the geometry of the cutting head used in Mobile Fidelity’s mastering studio in Sebastopol, California. The coils are made of OCC copper (Ohno Continuous Cast), a single-crystal copper that reduces discontinuities in signal transmission. The Micro-Line stylus, whose profile reproduces the shape of the cutting tool, traces the groove walls with a very fine contact surface. This type of profile puts less stress on the vinyl than a conventional elliptical stylus and accesses details buried in the microgrooves.

A few useful specifications: 3 mV output level, frequency response from 20 Hz to 25 kHz, recommended tracking force between 1.8 and 2.2 g, load impedance of 47 kΩ / 100 pF, weight of 9.7 g. The MasterTracker works with any MM phono preamp.

Isolated motor drive and belt drive

The motor is a synchronous AC unit running at 300 rpm, with its rotation transmitted to the platter by a belt. The Delrin® pulley has two positions for 33 ⅓ and 45 rpm speeds; speed changes are made manually by moving the belt, without removing the platter. The motor is decoupled from the chassis by damping materials that prevent its own vibrations from reaching the platter and stylus.

Power consumption remains under 5 W. The power supply accepts 120 V / 60 Hz, 220-230 V / 50 Hz, and 100 V / 50 Hz, covering most domestic electrical networks worldwide.

The figures announced by MoFi are wow and flutter between 0.017% and 0.025%, and a signal-to-noise ratio of 74 dB.

A removable cover and a few points to know

The UltraDeck comes with a smoked dust cover, hinged and removable. During playback, it is best to remove it to prevent it from picking up airborne vibrations.

The surface of the Delrin platter is smooth and hard. Without a record weight (MoFi’s Super HeavyWeight, sold separately), the record may slip slightly during cleaning with an anti-static brush. Adding a record weight improves record/platter coupling and corrects slight warps.

The UltraDeck’s dimensions (50.0 × 15.2 × 36.2 cm) and weight of 10.5 kg require a stable and sufficiently deep piece of furniture. The 10-inch tonearm extends a bit farther than a standard 9-inch arm: allow the necessary space at the rear.

Technical Specifications

Motor and Drive

• Motor: AC synchronous 300 RPM
  • Isolated from chassis
  • Enhanced speed stability
  • Reduced vibrations
• Speeds: 33 ⅓ and 45 RPM
• Belt drive
• Power consumption: < 5 W

Platter

• Material: Delrin®
• Thickness: 1.3” (≈ 33 mm)
• Weight: 3.1 kg
• High inertia
• Reduced background noise
• Improved playback continuity

Audio Performance

• Wow & Flutter: 0.017% – 0.025%
• Signal-to-noise ratio: 74 dB
• Very low background noise

Tonearm

• Ultra Tonearm: 10” straight aluminum arm
• Made in 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
• Lossless signal transmission

Phono Cartridge

• MasterTracker cartridge pre-installed
• Factory-optimized alignment
• Ready for immediate listening
• Optimized groove tracking
• Detailed and dynamic reproduction
• Perfect synergy with UltraDeck
• Optimized for MoFi sonic signature

Construction and Isolation

• High-rigidity multilayer construction
• Constrained Layer Dampening: aluminum + MDF multilayer structure
  • Resonance elimination
  • Sonic neutrality
  • Faithful reproduction
• HRS anti-vibration isolation, developed with Harmonic Resolution Systems
  • Floor decoupling
  • Reduction of parasitic vibrations

Dimensions and Weight

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

Sonic Signature

• Very high resolution
• Wide and stable soundstage
• Precise and deep bass
• Natural and detailed midrange
• Fine and transparent highs
• Smooth and immersive playback

Key Features

• Plug & play audiophile ready-to-use version
• High-end MasterTracker cartridge included
• High-inertia Delrin® platter
• 10” Ultra Tonearm made in USA
• AC motor isolated from chassis
• High-rigidity multilayer construction
• HRS anti-vibration isolation
• Very low background noise

Recommended Uses

• High-end hi-fi systems ready to use
• Audiophiles seeking a complete solution
• Immersive listening without complex setup
• Demanding collectors