bv130 specifications ?

does anybody have the specs for a gefell bv130 as used in mv691 or 692
?

ratio 6:1
that's all i have

thank you frederic, that anyway the most important information, I ponder of transforming a mv691 into a tube mic with a 6s6b. 1:6 might be just a wee bit to low ratio

you can wire the primary in series and get a 9:1 ratio as far as I know...

https://groupdiy.com/index.php?topic=54709.msg703727#msg703727

oh thanks for that !  ...of course all this has been done as I see now !

hehe, yeah. I was also planing a km54 build with these. that's how I found this information. 

what holds me off is that I know these mics quite well and I was never really impressed by the sound of the nickel capsules and although people say the capsules are almost identical, to my ears a km54 capsules sounds much better, but maybe the transformer is the bottleneck

The amplifier circuit also has some issues. Andreas Grosser makes some mods to it and people say it takes the mic to a whole nother level... So I think the capsules are not the problem.
Oliver Archut (RIP) also noted that the mics were very inconsistent as the parts in east germany were not that good... He also said to "update" the transformer.

Murdock said:

The amplifier circuit also has some issues. Andreas Grosser makes some mods to it and people say it takes the mic to a whole nother level... So I think the capsules are not the problem.
Oliver Archut (RIP) also noted that the mics were very inconsistent as the parts in east germany were not that good... He also said to "update" the transformer.

Click to expand...

Yeap, preamp need to be tweaked. This is main problem with Gefell older microphones. Tube and silicon.
For the parts it was huge oversimplification from Oliver side. There were times where Gefell used weak components, but this was for short period and rather much earlier.
Transformer "update"? Hmm...
Many people were dissapointed changing for modern replacements (especially in tube mikes), because Gefell transformers are part of the unique sound.  I would never change them and i love Gefell trannies. I used some in my builds.
Preamp mods - yes, changing transformers or capsules - NO
Since Oliver was mentioned, now waiting for the "troll"