Gefell UM57 transformers

[TLRT]

I'm refurbishing our(and some friends') Neumann Gefell UM57's, making new PSU's,recapping the mics,etc, some of the trannies are not working at all(primary wires have infinite resistance) Is it possible to repair/rewind them? Actually I already bought some TAB remakes, which are quite good. Mics have nice output and low noise after the mod.

 

[ln76d]

Sometimes it's possible and somtimes not. Depend mostly on your skills.
If you already have replacement and don't need transformers i could buy it from you for some decent price.

 

[Pip]

If you read what Oliver has written over the years about the stock UM57 and its various incarnations of transformers and core materials, it might not be worth rewinding the transformers you removed. I would venture to say that based on my experience with UM57's and Oliver Archut and AMI you have done what is best and if you want to take the time as a labor of love to resurrect an old transformer then please don't let me be the one to deject you. But it may not really be worth the effort in the end is all.


http://tab-funkenwerk.com/id72.html
http://recordinghacks.com/microphones/Neumann/UM-57

 

[hitchhiker]

For what it's worth.  I've used the AMI UM351 replacement in an older Gefell mic out of curiosity and it was different in that it sounded smoother and a tad fatter. I left it in the mic, too much hassle for the difference to put back the original.

http://www.tab-funkenwerk.com/id53.html

 

[TLRT]

I tried the AMI UM351 also,and I can confirm it sounded different. The old mics without modification sounds more "vintage". I'm also replacing the old PSU's as they are really problematic, caps dead, stabilizer tube dead(I cannot get NOS ones)

 

[ln76d]

PSU is problematic.
I recapped one and changed also rectifier diodes for silicone bridge. After that the voltage is high as hell (230V from the wall not 220V minus drop on selenium diodes), regulator tube also dead etc. I will need back to it and porbably try zener diodes instead the tube.

 

[micaddict]

If you read what Oliver has written over the years about the stock UM57 and its various incarnations of transformers and core materials, it might not be worth rewinding the transformers you removed. I would venture to say that based on my experience with UM57's and Oliver Archut and AMI you have done what is best and if you want to take the time as a labor of love to resurrect an old transformer then please don't let me be the one to deject you. But it may not really be worth the effort in the end is all.


http://tab-funkenwerk.com/id72.html
http://recordinghacks.com/microphones/Neumann/UM-57

My technical knowledge is not nearly good enough to judge this, but I do have something to say about it, if I may.
Consider the following.

Oliver Archut, albeit with few posts, was a member here. He is a true vintage audio legend. Unfortunately, he's no longer with us. Among many other things, this means he can't correct me if I'm wrong.  So I'll try to take extra care.

Oliver didn't particularly like the old Gefell electronics/circuits. He offered ugrade trannies and he shared mod schematics. But he also said that even after the mods they wouldn't be great.
I'll repeat, these are my own words, but I'm trying.
He also didn't particularly like Lorenz preamps (same story; poor electronics etc.), while others are all over these. Some even claim they're better than V72s and V76s.
He very much liked Telefunken tubes (like the EF86; he collected thousands of those, I believe) and Valvo to some extent, too. But not the  eastern tubes.

OK, now let's take a look at another vintage audio legend, viz. Andreas Grosser. This guy is an authority of sorts and people from all over the world send their vintage Neumanns to him to have them serviced.
Andreas does like Gefell, he's pretty fond of Lorenz preamps and he does like and use eastern tubes.

Both Oliver and Andreas were born in Germany.
But Oliver was from the west and Andreas is from the east.
There once was a curtain between them.

Could it be that the roots of these two giants made them a little biased?

 

[TLRT]

PSU is problematic.
I recapped one and changed also rectifier diodes for silicone bridge. After that the voltage is high as hell (230V from the wall not 220V minus drop on selenium diodes), regulator tube also dead etc. I will need back to it and porbably try zener diodes instead the tube.

Actually the PSU should have to work without the stabilizer tube, I tried mine without the tube, it is ok, but you need to readjust the voltages. These mics are quite frequent in Europe, they have a nice character for drums.(but they are not up to par with West Germany Neumanns) Mr Thiersch can reskin the capsules with very good results, the mic is easy to repair, I made many PSU's for them also.