- Category: Turntables
- Written by Jim Clements
- Published on 24 April 2012
The Design of the SOTA Nova Turntable
The manual for the SOTA Nova turntable posits that every variable important to turntable design can be solved with simple high school physics. These variables can be readily identified and addressed with a straightforward solution. This is the design basis for all SOTA turntables and the concepts can be grouped into four target categories - Dynamic Stability, Environmental Isolation, Control of Media Variables and Isolation from Electrical Impurities.
For Dynamic Stability and Environmental Isolation, SOTA uses a number of design features working together. To begin with, the sub-chassis is suspended by four damped springs. When properly balanced, each spring will stretch equally and since they are in tension, they do not experience any eccentric sideways deflections. The natural frequency of the suspension system is 2.5 Hz which is around the optimum natural frequency for a race car suspension. Is this coincidental? I'll explain more about the ingenious sub-chassis balancing procedure later in the "Setup" section of my review.
Another part of the Dynamic Stability solution involves the factory balanced platter. This platter weighs 14 pounds and contains a lead ring that gives the moving mass a high rotational inertia. Also, the platter comprises several layers of damped material, each with its own specific set of mechanical properties depending on each layer's place in the system starting with a top layer that is "impedance-matched" to vinyl along with another damping material that isolates the mat from the platter. SOTA calls this their "Constrained-Mode" design theory and a similar design concept also shows up in the fabrication of the sub-chassis.
The main bearing is formed from Ziconia and the thrust plate is sapphire. This bearing system is extremely low friction and long wearing. It can be expected to provide long-term low-friction performance with the endurance to last a lifetime. That's not just because of the material properties and their manufacturing tolerances which are above reproach, but also because the center of rotation and the center of gravity are coincident in the design and setup of the Nova. This promotes a super stable system with minimal wear.
Environmental Isolation is further promoted by way of the large, laminated armboard. The multi-layered armboard in the Nova is made from composite materials and features a bolt-through mounting system where the bolts not only go into the arm board, but they also go into the arm board well and then into the chassis, thus giving more rigidity.
To control Media Variables, SOTA has employed a special mat, a reflex clamp and a self-sensing vacuum hold down system. SOTA calls the Nova's mat a "vinyl format" mat because it matches the mechanical properties of vinyl. The reflex clamp is a very serious piece of hardware that clamps to the spindle with a levered compression fitting. It takes a little effort to set the clamp and I found myself holding the sub assembly from underneath even though SOTA says the springs can handle the load from setting the clamp.
The vacuum pump is contained in the same case as the outboard power supply. This utilitarian device has a black textured finish with a single red LED that indicates when the unit is connected to the mains power outlet. The box is the size of a large shoebox. It can be placed anywhere it will fit, but I found it best to place the unit on a carpeted floor. It is amazingly silent and effective in its operation. The vacuum holds down records with just the right amount of pressure. When combined with the clamping mechanism, mat and platter it mimics a system of infinite mass and damping.
The outboard power supply intrinsically isolates the table from power line impurities. But it is much more than a simple voltage transformer. It is a fully regulated power supply. SOTA fondly refers to this as their "Electronic Flywheel" and it features dynamic regulator circuits that are always on and ready for action. The AC synchronous motor has a balanced pulley with a switch to toggle electronically between 33 1/3 and 45 RPM.
The Nova table is supported by three adjustable feet that have felt pads on the bottom. An optional dust cover is available as well.
The good people at SOTA kindly included an SME 309 tonearm with the Nova table. This is the most affordable model in SME's 300 series of arms. It has a magnesium headshell while the shaft is formed of stainless steel and includes internal damping. The SME 309's other features involve design, material and geometric advantages that promote excellent isolation and resistance to warp related distortions. All signal wiring is linear crystal oxygen-free copper litz wire with gold plated phono plugs. But for me, I think the best part of the SME 309 is its spring-loaded adjustments that are cleanly set with the included ball driver. This is one of the easiest tonearms to install and adjust. It is nothing short of a total breeze to setup and tweak, a very noteworthy achievement in and of itself!
Despite all the SOTA Nova's technical and operational excellence, it may be easy to forget that it is a beautiful product to behold. The table is in a lovely real wood cabinet with precise dovetail joints at each corner. The Nova is available in a number of fine satin finishes. It is not a gaudy looking turntable with lots of shiny metal and delicate, attention-grabbing accouterments. On the contrary, the Nova is an understated product with both an underlying and outward beauty. I won't begrudge the shiny tables. Many of them are excellent. I just think the SOTA Nova is the model of pure competence and the pictures here don't do justice to its visual appeal. Its isolation and operation are so solid and reliable; I started calling the SOTA Nova the "Rock of Gibraltar".