Building an ergonomics model is about determining whether the proportions of the design are correct, as well as getting an overall feel for the sitting comfort of the chair – the seating height and angle, the knee support, the curvature and angle of the back rest, the height of the arm rests, the width of the seat and so on.
As detailed and important that the learnings to be gained from the ergonomics model are, the actual model itself is a simplistic construction made out of plywood, rubber- and styrofoam and cardboard. Seen from the “outside” it is quite a surprise as to how revealing and close to the final “feel” that you get from such a model. On the 30th January 2009, Jonas and Michael met to build the first model.
Jonas had printed out 1-to-1 full scale drawings of the Ballerina Sweetspot seen from the front and side view. From the side view drawing, we cut out two pieces of plywood board with the exact curvature of the chair as well as with the intended height from the floor. From the front view, we cut out planks of plywood with the intended width of the chair at different intervals. Put together, the plywood pieces formed what looked like a designer and carpenter’s nightmare – but was a true life representation of the the Ballerina Sweetspot. Then we tested and added rubber foam of different heights and densities – achieving the “closest” possible feel even adding further lumbar and neck support.
Built in the workshop and corridors of Konstfack, the model was then tested on people of different heights and builds – ranging from 1m 60cms to 1m 88cms in height and from 65 kilos to around 120 kgs.
And from this, we learned that the design needed to change in a number of areas:
- The height of the chair was reduced by 6 cms to lower the chair to an initial starting height of around 41 cms.
- The angling of the seat was increased – to provide a more relaxed sitting position without losing the involvement in the actual listening experience – placing the rear of the seat almost 9 cms lower than the front of the seat (knee height).
- The width between the arm rests was reduced from 85 cms to 75 cms.
- The arm rests were also angled inward slightly to better support the elbows.
- A few adjustments to the height of the arm rests as well as the distance between the back of the arm were made. Even at this early stage, people testing the chair were letting their fingers caress the curve of the arm rest when seated.
Based on the observations from the ergonomics model, Jonas made the final changes to the CAD design of the Ballerina Sweetspot – and it truly had become a beautiful listening chair and a design worth protecting.
On February 25th 2009, the Ballerina Sweetspot was granted a European design/pattern registration.
But there was still no real chair to sit in. 
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