Ok, another one out from the list of unfinished projects.
I had problems to find all the stuff needed to build PSU for it (still have many things packed in many boxes
).
For PSU i used parts which i had, maybe it's not so best design, but works great, very silent.
Both sections are regulated, Heater with 7805 and B+ with 62V Zener (35.5V direct on plate).
In the final build i used NT1a edge terminated capsule and 6.3:1 Funkwerk Leipzig transformer.
I also had to remove internal mesh from headbasket - it's definately better.
Few words about high impedance resistors from grid to ground
I tested 100M, 1G and direct capsule to grid connection in A/B comparison.
Between direct capsule connection and 100M there was probably difference in low end, probably because if it even was it was very subtle. To be honest, i'm not sure it wasn't only illusion.
Between 1G and direct connection there wasn't difference at all.
Microphone is very quiet, no problem with noise, distortion, hum or hiss.
Output transformer - i'm too lazy to test other transformer in this mike
There's probabllity that output impedance is too high, because with NT1a capsule it sounds really smooth.
Overall microphone have pretty strong output and sound incredibly pleasant.
I'm keeping it as it is - i'm fully satisfied.
Pretty good capsule for it could be 32mm K67 (definately most of chinese microphones could be really good donor for this project - MXL2006 could be good candidate - pretty ok headbaset and look as also 32mm K67).
If it would be too bright, then there's an option to use cap from plate to ground.
In my build audible difference starts from 390pF, but i don't have any need to use it.
Again - worth to build