Help with u48 wiring

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salomonander

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Im building my u48 from schematics and some ebay photos :) i have most things worked out, but im uncertain in two areas.

- looking at the pic, the right side of R5 needs to connect to the main 105v rail. I cant see what they are doing due to perspective of the pictures. Is it connected directly to pin5 of the tuchel connector? Or do they take it from somewhere else? I assume the cable runs on the turret boards backside.

- my haufe transformer features two additional brown cables - which i assume are for grounding. It also has two eyelets on each side of the lamination. Do i simply have to solder the brown cables to the eyelets?

Thanks a lot!

Ps: if anyone has more pictures of a u48 inside - i would not mind :)
 

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salomonander

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Photo of the turret board.... where does the right leg go on the top resistor?
 

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salomonander

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Additional brown leads. The eyelets are connected to the mounting screws.
 

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Banzai

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Brown leads are the electrostatic shield. Connect them anywhere to ground.

Easiest is same place as black lead.

 

salomonander

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Banzai said:
Brown leads are the electrostatic shield. Connect them anywhere to ground.

Easiest is same place as black lead.

Thanks a lot. Still trying to find out about that 150M resistor. Anyone?
 

Banzai

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salomonander said:
Thanks a lot. Still trying to find out about that 150M resistor. Anyone?
The wire from Tuchel pin 5 goes directly to a turret: can be R5, R6, R8, or R9 (looks like it's wired to R8 from your picture). Then all these parts are wired together between them.

The right side of the 150M, you can connect it to the turret of 30K, 3M or 1780. Whichever is most convenient.
 

Moby

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salomonander said:
Im building my u48 from schematics and some ebay photos :) i have most things worked out, but im uncertain in two areas.

- looking at the pic, the right side of R5 needs to connect to the main 105v rail. I cant see what they are doing due to perspective of the pictures. Is it connected directly to pin5 of the tuchel connector? Or do they take it from somewhere else? I assume the cable runs on the turret boards backside.

- my haufe transformer features two additional brown cables - which i assume are for grounding. It also has two eyelets on each side of the lamination. Do i simply have to solder the brown cables to the eyelets?

Thanks a lot!

Ps: if anyone has more pictures of a u48 inside - i would not mind :)
Most elegant way to connect the R5 (high side) is to use wire on the back side of the board and connect it at the 30k-3M junction. Regarding the Bv.08 electrostatic shield, original Bv.08 has no shield. I presume that Haufe did some modification to compensate one chamber bobbin. Original one use the 4 chambers bobbins. Does it affect the sound? Yes. Does it sound correct? Well, yes, but It's not the Bv.08, but some modern recreation. Connect those shield wires to the ground. :)
 

salomonander

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Thanks a lot! Moby, you say the haufe isnt spot on. Any other available recreations that are 100% correct? Best

Oh, and do you know if this haufe is made for the .5uf output cap?
 

Delta Sigma

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salomonander said:
Thanks a lot! Moby, you say the haufe isnt spot on. Any other available recreations that are 100% correct? Best

Oh, and do you know if this haufe is made for the .5uf output cap?

Ha! You're talking to the man! My experience is that Moby's transformers sound the best and the prices are more than reasonable. As far as exact recreations go, he's gone a long way to see that his transformers are historically accurate to certain transformer versions. Some people here have done shootouts of Moby vs originals and can't tell the difference. I just know they sound good.
 

salomonander

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With so many mic experts in the room i want to ask if anyone can point me towards a source for the cable holders (see pic) preferably in the eu.

And just so i learn a little.... am i correct in assuming, that star ground wiring is not necessary in a mic? I just borrowed an original u47 from a friend and the mass is all over the place - using eyelets on the transformers mounting screws for distribution. Im not certain if the wiring is original though. It also has a direct connection from the tuchel pins 3,4,6 to the base of the housing.

 

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Moby

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salomonander said:
Thanks a lot! Moby, you say the haufe isnt spot on. Any other available recreations that are 100% correct? Best

Oh, and do you know if this haufe is made for the .5uf output cap?
Hey, I really don't want to judge about Haufe Bv.08, but I always react when I see someone call it "original". I don't say you call it original but some places share that missinformation. Unforrunatelly it's not original it's just one more Bv.08 replacement. I don't know how this transformer pass low end with 0.5uf, but generally 0.5uf is moving U47(8) low end -3db spot on the higher value than 1uf. Call it "integrated high pass". Regarding my Bv.08 recreation, it's also not "original", but I did my homework regarding size, winding scheme, 4 chambers bobbins, bobbins material, laminations heat treatment, etc. So, people who installed it in their microphones are telling great stories about it. I'm really pleased and thankfull because of that :)
 

Banzai

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Choice between 0.5uf and 1uf depends on where you want the bass resonance point:

0.5uf -> 40hz
1uf -> 30hz

Resonance at 40hz is more audible and compatible with more systems. Gives the impression of more lowend. Same effect in the C12.

It's counter-intuitive as most people think you need to increase the coupling cap value for a "bigger" low-end. But it's the other way round.

The Haufe can be used with 0.5 or 1uf.
 

salomonander

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Thanks so much guys! Awesome :) Im almost finished. Still looking for these cable holders (or are they bent solder pins?). Any source?

Best
 

salomonander

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Turns out that these cable holders are indeed just solder eyelets  that were bent. At least thats what i came up with. It works and looks just like the original. Im done with this built. Thanks so much everybody. You offered great help!
 

Moby

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salomonander said:
Turns out that these cable holders are indeed just solder eyelets  that were bent. At least thats what i came up with. It works and looks just like the original. Im done with this built. Thanks so much everybody. You offered great help!
Great, to be honest, I never payed attention on that detail. Thanks for sharing that. Share some photos when you finish it :)
 

Delta Sigma

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salomonander said:
Turns out that these cable holders are indeed just solder eyelets  that were bent. At least thats what i came up with. It works and looks just like the original. Im done with this built. Thanks so much everybody. You offered great help!

Photos of the completed build please!
 

salomonander

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Here you go. Only thing im not so happy with are the huge ceramic caps. You can see one on the acrylic board. The original dogbones were lots smaller. But after browsing ebay for a month and only finding one - i gave up :) in case anyone has the correct ones as in pic three, please let me know. I also gave up on the 1uf Bosch MP as the three i could find driftet over 70%. Found a good siemens MP though. The 0.5uf is a bosch and measures fine.
 

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Delta Sigma

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Looks great! Remember, it never hurts to have an extra transformer lying around for a future build. Consider buying a Moby BV.08. Not only do they sound great (I can't compare to Haufe as I haven't heard it though), but they look more "vintage" than the Haufe.

What capsule did you use? Is that one of Dany's bodies? If you A/B those output caps, update us on which turned out the best.
 

salomonander

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Thanks. Yes, i might do a u47 next, now that i know how it works. Ill try the Moby transformer then. I used a flea body. Capsule is a neumann k49. Thanks for the advice. Best
 
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