MoFi UltraDeck: High-quality turntable made for audiophiles

MoFi is short for Mobile Fidelity Sound Lab (MFSL), and the company is well known among audiophiles for its high-quality vinyl, CD and SACD releases. Two years ago, she decided to design her own turntables, heads and phono stages “to reproduce her releases correctly.” UltraDeck is the older of the two models currently in production. And it is not as simple as it might seem at first glance.

The Mobile Fidelity Sound Lab specialists were well versed in how to record music, restore old tapes and digitize them, but they had no experience creating electronic components. But the good thing about the modern world is that many problems can be solved through outsourcing. In this case, the main thing is to correctly set the task, and in our case it could be formulated as follows: to develop an easy-to-use player with a neutral sound, the production of which will not require large financial costs.

Allen Perkins, a designer at Spiral Groove, known for its high-end turntables, was invited to design it. For him, the proposal became a real challenge: in Allen’s own words, he got the opportunity to prove that the basic design principles can be implemented in an affordable price segment. By the way, John Shaffer, the former owner of Wadia, became the director of the newly formed MoFi Electronics division, so the production of players was organized at the same factory in Ann Arbor (Michigan), where electronics of this brand are still produced.

Perkins has designed two models – the StudioDeck and the more advanced UltraDeck, which is what we’re going to listen to. The width of the hull was increased to 50 cm, this was necessary so that there was enough space for the engine. The table is made of MDF, and three sheets of aluminum of different shapes and sizes are glued to its top surface. Due to this, resonances are calmed down and the three main components – the motor, the main bearing and the tonearm support – are partially isolated from each other.

The AC synchronous motor is mounted in the far left corner of the table and is further isolated from it through a flange made of vibration-absorbing Delrin polymer. A support disk 3.3 cm thick and weighing just over 3 kg is machined from it. Since this material with a microcrystalline structure effectively damps resonances, the record is placed without an intermediate mat. The bearing is inverted, i.e. the shaft is pressed into the disk, and the hardened steel axis is pressed into the base of the turntable.

Speed ​​switching 33/45 rpm. in MoFi UltraDeck it is done manually by transferring an elastic belt to different stages of the drive pulley. The power supply system is built into the table; the player is connected to the network via a standard three-pin IEC input. The custom 10″ long tonearm has a straight tube and a gimbal swivel assembly on precision ball bearings. The internal wiring from the shell to the RCA output jacks is made with thin Cardas wires. Anti-skating is classic – a weight on a string. The turntable body is mounted on four decoupling supports manufactured by Harmonic Resolution Systems. The entire assembled structure weighs 10.5 kg.

The MoFi UltraDeck model comes standard with an UltraTracker MM head with an elliptical needle. And although it also has the MoFi logo, it is custom-made by the reputable Japanese company My Sonic Lab. An interesting feature of this cartridge is that it has a V-shaped “engine” – an assembly of two magnets located at an angle to each other. Reproducible frequency range 20 – 25000 Hz, output voltage 3.5 mV with a standard load of 47 kohms.

Characteristics  MoFi UltraDeck:

– Drive: Passive
– Speeds: 33/45 rpm
– Platen weight: 3.1 kg
– Main bearing: inverted
– Knock level: 0.017% – 0.025%
– Rumble level: -74 dB
– Motor: asynchronous 300 rpm
– Power supply: built-in
– Mains power: 100 – 230 V 50/60 Hz 20 VA
– Power consumption: <5 VA
– Dimensions: 500 x 152 x 312 mm
– Weight: 10.5 kg
– Tonearm Effective length: 10 inches
– Offset: 22.8° (adjustment ± 2°)
– Needle entry: 18 mm
– Effective weight: 35 g
– Weight of installed heads: 5 – 10 g
– UltraTracker head Type: MM (double magnet)
– Weight: 9.7 g
– Clamping force: 1.8 – 2.2 g
– Resistance/capacitance load: 47 kOhm/100 pF
– Frequency range: 20 – 25000 Hz
– Needle profile: ellipse
– Output voltage: 3.5 mV