Hello, while i wait for some parts for restoring my sra12s i made some new earpads for my sigmas.
I also made the internal dampening. Following the advice of Spritzer i used the most dense material i could find.
By pure luck the material and quantities i used seems to be ok. The soundstage seems here, definitely the best of the headphones i own. The bass is present and clear so i am pretty happy of the final result.
I decided to substitute the earpads because i don't feel comfortable using earpads that have been used by someone else for 30 years...
I decided to not use a spare pair of lambda earpads because of the different shape of the lower back part.
I made them in leather following the procedure Stax (or their supplier) probably used.
I used an embroidery machine to sew the ear oval on the reverse side of fabrics, then i reversed the fabrics.
With the fabrics now on the right side i added some low heigh memory foam cutted a couple of mm smaller than the finished earpad.
Now i used the embroidery machine to close the earpads. Cutted the excess leather and here they are.
They are a bit bigger than the original ones and are less stuffed, nothing dramatical but i will remade them the next time i have time to use the embroidery machine.
The same method can be used to make them with a sewing machine for the oval and an overlock machine using 3 threads and a short lenght stitch.