Neumann U67 Clone : D-U67 Tube Microphone Build Thread.

[HellfireStudios]

a (noob again) question about flux.
in my other projects i didn't clean flux because there's not much and i don't use extra flux.
now this is my "smalest" kit and i wonder if it is super important to clean the board cause i don't exactly know how to do this ?

as i understood from main topic : 0.1A fuse for europe 210v is fine ?

91% Isopropyl Alcohol and a toothbrush. Be aware that styrene caps don't gt along with alcohol, so you should clean the board just before installing those.

-James-

 

[Le Roux]

Finished my U67.

Iaudio transformer
NOS Telefuken EF86 from Cristian
Ben's capsule

On a comarison with Iaudio MK47, we found the MK47 to have more presence. It was chosen in all preamp-compressor combinations we tried.
The U67 was a little too bassy. (Atleast on my friends vocals)
I have all the jumpers in as factory default.
Should I try removing them or try a different tube?

Thanks for any suggestions.
Neil

 

[poctop]

Finished my U67.

Iaudio transformer
NOS Telefuken EF86 from Cristian
Ben's capsule

On a comarison with Iaudio MK47, we found the MK47 to have more presence. It was chosen in all preamp-compressor combinations we tried.
The U67 was a little too bassy. (Atleast on my friends vocals)
I have all the jumpers in as factory default.
Should I try removing them or try a different tube?

could you let us know what you have as short and open in term of jumpers and fonctionnality.
do you have a shorting jumper on S2 internal Switch ? that will affect the bass response.
S2 should normally be short for Vocal operation.
Best,
Dan,



Thanks for any suggestions.
Neil

 

[dgoszillai]

Ok as there's not so many info on the europe version here is a picture of what i did for the ones who could need it.
and because i'm not that great at electronic of course if you find any error please tell me before i power this and blow my house !  8).

 

[micaddict]

Finished my U67.

Iaudio transformer
NOS Telefuken EF86 from Cristian
Ben's capsule

On a comarison with Iaudio MK47, we found the MK47 to have more presence. It was chosen in all preamp-compressor combinations we tried.
The U67 was a little too bassy. (Atleast on my friends vocals)
I have all the jumpers in as factory default.
Should I try removing them or try a different tube?

Thanks for any suggestions.
Neil

The U67 was designed to have less bass than its predecessor, the U47, especially in close proximity.

Like Dany said, the S2 short is an important part of that. Most U67s are used like this, but it can be changed.

In other words, if a particular U67 sounds bassier than a particular U47, there's likely something not up to spec in one of the two or in both. Especially if the U67 is in the common vocal mode.

BTW presence is not the exact opposite of bass. They can coincide as they typically do in a good U47.
Some experience the U67 as a dark microphone. I wouldn't necessarily agree, but regardless, dark is not the same as bassy.
Also, presence is sooner a high-mid than a treble thing, I'd say.
FWIW


Henk

 

[imo]

sorry to keep harping on this, but does anyone have any ideas on spec voltage for a U67. I built Dan's circuit, and in changing the tube have about 83vDC on the plate. I know its right on the edge of the 10% that people spec out for tube circuits, but with this one has anybody dealt with this? My cathode seems to be in spec, at 1.7v
Dan, have you run into this with any of your circuits?

 

[poctop]

sorry to keep harping on this, but does anyone have any ideas on spec voltage for a U67. I built Dan's circuit, and in changing the tube have about 83vDC on the plate. I know its right on the edge of the 10% that people spec out for tube circuits, but with this one has anybody dealt with this? My cathode seems to be in spec, at 1.7v
Dan, have you run into this with any of your circuits?

The Difference in plate current should be arround 0.9 at 75Vplate and 0.833 at 85 plate = 0.066ma difference,  and the tolerance is from 0.8ma to 0.9 ma so you really dont have to worry. each tube from their variation will sit at slighlty different spot in a self bias type circuit ,  if you notice from the schemo the  75V CA is approx !,  you are sitting right in the zone , if the mics sounds great no worry about that,  it will also depends on the heater you feed it as well,
Hope this helps,
Dan,

 

[poctop]

Ok as there's not so many info on the europe version here is a picture of what i did for the ones who could need it.
and because i'm not that great at electronic of course if you find any error please tell me before i power this and blow my house !  8).

Everythings look good from here ,  does your iEC have the fuse in there also ,  just wnat to make sure because some dont ,
always a good thing to fuse it before testing , looks great Thanks for the taking the time in doing this ,

Best,
Dan,

 

[dgoszillai]

great thx
yeah i put a 0.1A fuse as i understood from your first post.
EDIT : dam that 0.1A (time lag) just blew of. it blows right away again if i change it. I red somewhere maybe 0.2 would be better ?
i have a little problem. reading this thread i can't understand enough to go through the calibration
what i read about "plates" or "unloaded" "B+ and heater" are not clear for both my french and my skills (!)
is there somewhere a 101 procedure that i could follow step by step ?

for what i undertand i should measure this ? :

 

[Joekkel]

yep, tha'ts right, in europe you need a 0.2A fuse. and the pics right too, 210V on B+ and -6.3V on H-

 

[dgoszillai]

joekkel thx alot i'll go buy a 0.2 right now to test this
means that this info on first page is wrong ?

fuse will need to be 0.1A instead of a 0.2A for north America

about this B+ and H- they are the same on min mic PCB as in the PSU PCB ?
means i must read 210 @ B+ on that PSU PCB as well as 210 @ B+ on main mic pcb
and same : -6.3 @ H- PSU PCB and -6.3 @ H- mic pcb right ?

 

[Joekkel]

joekkel thx alot i'll go buy a 0.2 right now to test this
means that this info on first page is wrong ?

nope, i was wrong, just checked the fuse i installed, it's 0.1A. sorry for that, i just remembered buying both values...

about this B+ and H- they are the same on min mic PCB as in the PSU PCB ?
means i must read 210 @ B+ on that PSU PCB as well as 210 @ B+ on main mic pcb
and same : -6.3 @ H- PSU PCB and -6.3 @ H- mic pcb right ?

exactly, but B+ on the psu-pcb will only read around 210 when the mic is connected, with no load it will be higher

 

[dgoszillai]

dam ..
i installed 0.2 and it's going fine now ... so i'm sure 0.1 will blow up again.
without reading your post i checked 220v on B+ and -16 on H- without the mic.
B+ trim works but H- trim doesn't lower this value so i guess something's wrong  :-\

 

[tskguy]

Hey,

Make sure and check the voltages with the mic connected. The Heater voltage with out a load is high like that. In fact I am sure 16 is as low as I could get it.

Eric

 

[imo]

Thanks Dan. Heater is around 6.1..Everything else is good, and as before the mic sounds fantastic. I loved the Tele tube i had, but it was too noisy

 

[dgoszillai]

hi tskguy
thx for support you were right -16v droped and i can trim it very easy. now the problem is B+ that doesn't go high enough.
ok so i read after 20min warmup (still with that 0.2A fuse)
PSU B+ = 202v (max)
MIC B+ = 202v (max)
PSU H- = -6.5v
MIC H- = -6.43v (strange there's a difference ?)

Winetree i red you had same values 202v / 6.3 after warming up 15min
did you change that 56k ? to what value ?

 

[tskguy]

Hey,

202v would most liklley be just fine by the way. If it were me I would just try it.
Over 210 would be more of a concern.
Eric

 

[dgoszillai]

ok so i pluged it !

hell this thing sounds amayzing ! i can't do some major recording tonight because of neigbhoors but wow what a presence on a talking voice ! can't wait to do more audio tests.

 

[Winetree]

Don't remember off hand. Try something like 47K.
You can always adjust the value if that doesn't get the adj. pot in range.

 

[tskguy]

So glad your mic sounds good! Please make sure and post some sound samples when you have the chance to do some recording.  And if you want to get the voltage absolutely correct winetree's suggestion would most likely get you there.

Eric