Light Weight Vinyl Record Turntable

Leoht has been 3 years in the making. I started developing Leoht in the second COVID lockdown. I underestimated how complex the project would be, and there came a time where the challenge seemed too great and the project was temporarily shelved. Leoht is a culmination of everything I have learned through many years of research, trial, error and success in turntable design and the teachings of my engineering influences.

Leoht is based heavily on the engineering principles of Rega Research, headed up by CEO Philip Freeman and co-founder Roy Gandy, engineers for whom I have great respect. Rega’s low-mass, high-rigidity principle is unique in the industry, founded on knowledge accumulated in material science and physics.

The chassis of an ‘ideal’ turntable is one where mass is reduced as much as possible while stiffness is maximised, with a compromise reached between the two depending on the materials available and the cost of the product if production is the ultimate goal. Accuracy is key, with components machined to microscopic tolerances that push the limits of the materials used and in many cases exceed what is achievable with current production techniques, necessitating the development of new methods of manufacturing to achieve components that meet the desired tolerances. Most of those tolerances measured in micrometers, a thousandth of a millimetre or one thirtieth of the diameter of the average human hair.

The plinth is the chassis onto which every component of the turntable is mounted. It forms the supporting structure for the drive system and pickup arm and should be as light as is practical yet as stiff as possible. The shape of the plinth is optimised to remove as much material as possible to reduce its mass, but to also control resonances within the plinth that may be excited by vibrations born from the bearing, motor and arm as well as airborne environmental vibrations.

For the core of the plinth, Rohacell, a foam based on PMI (polymethacrylimide) chemistry was used, which is incredibly strong, when used as a core material in a sandwich panel. Commonly a HPL laminate is used, but with the Leoht, based on testing, it uses a quasi-isotropic carbon fibre layup with 0°/90° and 45°/-45° fibre orientation. This layup technique offers improved stiffness across the diagonal axis of the panel and significantly improved torsional stiffness. The laminates are sheets with fibre type, weight and weave symmetrical from the front to the back ply to maximise stability and flatness.

The plinth and all adhered components are bonded with Permabond Adhesive, which is a two-part structural Epoxy resin adhesive. Laminating a closed-cell foam is not as easy as it sounds. The adhesive has to fill the tiny pockets between the cells, but must be compressed sufficiently to produce a perfectly flat sandwich panel without excessively stressing the foam core. Excessive adhesive can be absorbed into the foam to a degree, but will only add unwanted mass and structural damping.

The other non-composite parts were made or sourced using the same principles and desire for quality and light weight. This included the main bearing and motor, the spindle, the feet, the arm and the platter which was a precision machined piece of Delrin plastic.

After three years everything had finally fallen into place and I connected it up for a listen. The sound is quite astonishing. My long-standing point of reference is a Technics SL-1200G. Leoht does a better job of unearthing micro detail in a mix and better portrays dimensionality and spacial information in a mix.

My intent with this project was originally to build a statement piece, and one that would stand as my last turntable design. I thought I had achieved that and there weren’t plans for a follow-up, but restless minds never stop so Leoht 2.0 is already in the works. There is a lot of scope to further reduce the size and mass of the plinth, while greatly increasing its stiffness in key areas. By my estimates I think I can cut the weight in half and increase rigidity in key areas at least three-fold using the same materials. Now that I’ve proved its efficacy, I can envision future designs that will push these ideas to their limits and beyond and I’m excited to see how far I can take Leoht.