LTA Headphones

A modular, open hardware framework for high-end headphones

Nov 18, 2020

Project update 3 of 5

Additional Design Improvements

by Tomislav Liber

This update continues our look at small design improvements to the headphones not present on the prototypes, but which will be on the production models. As promised last week, the main hinge yoke designs have been finalized, again by utilizing laser cutting to manufacture small, precise metal pieces that can be combined with 3D printed plastics in order to improve the performance and feel of the hinges. These design changes affect both the V1 and V2 3D printed models, but not the V2 CNC machined model.

Hinges - As mentioned in the last week’s update, the 3D printed headband sliders will have M3 grub screws permanently screwed and glued to them for ultimate durability. These screws will then attach onto the V1 and V2 hinge yokes through a specially machined nut and two laser cut stainless steel plates.

The upper plate will be have a dual function. It will be permanently glued into the designed socket on the plastic yoke to provide a perfectly flat, very solid, smooth platform for the bottom of the plastic headband slider to sit on. This will provide very smooth rotation and prevent wear. In addition, it has an aesthetic purpose, as it will be brushed to the exact same surface finish as the stainless steel plates on the sliders themselves presented last week. This stainless steel detail will give the hinge assembly an additional touch of quality.

The bottom plate will be permanently glued into the designed socket on the bottom side of the hinge yoke, providing additional stability to the plastic part in an area of high stress, and providing a flat, smooth platform for the nut to sit on. The nut itself is a specially machined, round slotted nut perfect for such applications. It’s only 2.5 mm high with a 6 mm diameter, so it doesn’t take any more space than a regular screw head would. At the same time, it can be easily removed which eliminates the need to unscrew the grub screw from the slider itself. The nut will be held in place with industrial thread locking adhesive for additional security and the surface between the nut and the stainless steel plate will have damping grease applied to it, to ensure smooth rotating action, similar to that found on volume pots.

Hinge yokes – The LTA V2 3D printed yokes will be additionally mechanically improved with laser cut stainless steel inserts. The purpose of these inserts is to provide extra rigidity to the yokes in the front-back direction relative to the ear cups and to prevent even the slightest deformation during under extreme loads. While the yoke’s carbon fiber reinforced plastic is very durable in itself, adding these steel plates will increase the rigidity by about 40%, depending on the direction of the load, while increasing the weight by less than 10%, so it’s a good trade-off. The cost of production of these steel plates is insignificant as well at less than $1 per unit.

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