Thanks for the info on the transistor, always wondered what that thing does in there.
So for for the Plexiglas capsule base: That is quite easy to do really if you can use a drill press, basic lathe and preferably a band saw.
First I drilled the holes into the Plexi block.
Then cut it out and sanded it roughly round
Then went to the lathe. Now very few lucky ones may have a stepped ring collet to hold the piece. A simple but convenient solution here is to apply douple stick tape to the chuck jaws and then use the tailstock to center the work and press it against the chuck. Works great.
With the domed profile cut
After fine sanding it can easily polished a high gloss, glass like surface. Just take care not to overheat the material during sanding/polishing. To remove remaining polishing compound it´s best to use an ultrasonic cleaner filled with warm water and some mild dishwashing detergent (alcohol would immediately crack the piece).
I also made a new capsule holder from some PVC scrap and bought a threaded rubber element with elasticity suiting the capsule´s weight.
Components of new capsule base assembly:
So after all the effort I didn´t wan´t to go with the stock capsule anymore and put in something decent
It´s a K49 and the two sides are matched remarkably well.
Eventually the shape of the Plexiglas base is nothing new at all. It turned out to be pretty similar to a U67/M269-base and of course the dome now starts just at the lower grille entry ( failed to re-invent the wheel in this regard though as someone already was that clever half a century ago).
The very thin braids that connect the capsule are not my own idea as well. I´ve got that from a meanwhile retired guy of AKG´s manufacturing department who contributed that to the X-series C414´s (which have a fantastic shock isolation of the capsule thanks to it).
I compared the mic to an all original M49(with K49). Overall sound balance is very similar. However the M49 has a juicy sweetness to it and a charme that all AC701 mics I heard so far share. The (Ex-)Brauner is extremely clean and clear throughout it´s dynamic range and stays true even at quite massive SPL´s without any signs of saturation. But if you look for Mojo look somewhere else.
That might not be the end of the story but the "wrongness" that originally bothered me has gone. Quite a step up.
