HAUFE BV107 original Neumann KM84 transformer GROUP BUY CLOSED!

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delaymix

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TillM said:
I'm really excited how they sound compared to the cinemag.

Do you think there is so much difference? Is it clearly remarkable?

Maybe there are people interested in arrange a second round of these transformers...
 

TillM

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So guys, I can confirm that the Haufe fits Banzai's PCB.
The only thing is, that you have to extend the transformer cables, cause they are really short.
Put everything together 10 minutes ago and it works perfect.
Was to lazy to bias the fet right now, but will it do another day.
Tomorrow I can test it together with the cm5722 transformer.
 

[silent:arts]

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delaymix said:
Maybe there are people interested in arrange a second round of these transformers...
Good luck. I was on the phone with Haufe yesterday
(since I'm still waiting for transformers I ordered in July).
They told me leadtime for new orders is 50 weeks at the moment.
 

kominak

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Feb 6, 2006
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Just trying my luck here, but if any of you guys decided you don't need 1-2 of these transformers, send me PM...

Martin
 

Jim50hertz

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This is presumably now an available part from Haufe then Rainton? But a custom order?

If I manage to get in on Banzai’s bodies before it closes I would very much like the original trafos on board.

Any chance of another group buy?
 

iturnknobs

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TillM said:
So guys, I can confirm that the Haufe fits Banzai's PCB.
The only thing is, that you have to extend the transformer cables, cause they are really short.
Put everything together 10 minutes ago and it works perfect.
Was to lazy to bias the fet right now, but will it do another day.
Tomorrow I can test it together with the cm5722 transformer.

Could you provide any info for wiring this trafo to KM84 circuit? Mine seems to test properly except I cannot seem to come up with a 200 ohm secondary impedance, regardless of my configuration.
 

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maarvold

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Just a warning: on one of my group buy BV107's, a couple of extremely thin lamination shims fell out of the stack on one side; also one of the end U-shaped laminations moved a little bit.  I replaced the shims and pushed the U back into place and everything looked perfect.  Then I called my friend--former chief engineer for Jensen Transformer.  He suggested putting clear nail polish on them so that "capillary action" (a phrase he used several times) would wick little of the polish in between the edges of the laminations and glue the whole stack together. 

The only polish I could find on the shelf was a bit thick; using internet advice, I thinned it down a bit (a couple of drops of isopropyl alcohol in maybe 8 drops of polish) and painted it on with the brush from the nail polish.  Work quickly--mine seemed to be fully dry in just 2-4 minutes.  If I had it to do again, I might make the polish even a bit thinner and put a bit more on the laminations (for better "capillary action"). 
 

TillM

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at one of mine BV107, the black wire fall out the lamination, when I soldered it to the pad.
Really really s****y !
Write Haufe and hope, that I can fix the problem.
The black wire should be ground, any ideas how I can fix it?
 

volker

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If the wire colors are identical to the old transformers, black is the beginning of the winding. So I wouldn't get my hopes up for an easy fix... Post a photo?
 

Winetree

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I had the white/black wire pull out when trying to solder the 2 whites together.
The end of the white wire was tinned but didn't look like it was soldered to anything inside.
Can this be fixed.
Having the same lamination problems. Thanks for solution.
 

TillM

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So here’s a photo.
I can’t not measure any resistance.
The other coil has 65ohm resistance.
Well, I think it’s hardly to fix, maybe it’s impossible.
First time this ever happens to me and in the meanwhile I build tons of things.
 

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volker

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So the wire is still connected? If you can see part of the actual magnet wire, you could try to resolder. Otherwise there isn't much to be done other than rewind, since the black wire is the beginning of the wind.
 

TillM

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Hi Volker,
No it’s not connected, I put it in for the photo.
Also talked to Moby meanwhile, the transformer is not repairable.
Just what you say, only a rewinding will rescue them.
I build so many mics and other stuff, this is the first time this happened to me.
As we say in Germany, I paid “Lehrgeld”.
 

Klimaschewski

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Apr 2, 2017
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Hi Everybody,

Since the Banzai KM84 Clone project is going through the 2 batch, I wonder if we should start another groupbuy for the Haufe BV107?

@rainton would you possibly again carry out a round?
For all those who are also interested, please write briefly in here.
i would be in for a Pair!

Can someone please also write in here how they sound compared to a Cinemag or the other options available? :)

Many Thanks
Klimaschewski




 

maarvold

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Feb 1, 2009
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I would be in for 3 if the wait wasn't super-long--several months would be ok, but hopefully not into 2022. I built 3 84s from the second round and the one with the Haufe is my favorite. The other 2 had AMI transformers.
 

Klimaschewski

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Apr 2, 2017
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i'm totaly with you maarvold.
I send them an E-Mail for a small batch and post it in a new thread if i hear something from them.
many thanks for the feedback about the AMI trany!
I would love to hear how those tranys compare soundwise..
Brigther, more lowend. Golden super ultra mega rare tubeish :)
Maybe in another thread!.
so this thread is closed..
 
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