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

[wave]

Thanks Dany!
I plan on working on the build manual this weekend. I have around 220 pics of my build.

Dave

 

[ktfstudio]

Got to say that pot holder/shield idea is inspired.
I have been experimenting with tubes and different sides of my k67's. My gosh, those 2 items are supper critical. The best combo I have is a Tungsol with a Steven Paul reskin. All the tubes have a big difference, not counting the noise. It's like how many doors are between you and the source.  I've tried 3 nos Telefunken tubes and they are all bad, money down the drain. Maybe they have been all picked through. Thinking I got to pull the trigger on some $65 tubes with the return option or maybe another Tunsol.  I'm trying to decide about new Neumann caps or a reskin of my old Neumann's. I feel like I'm almost there. The amp is fine, I only need to compliment them with a great tube/cap duo to reach the promise land. Luck to all!

 

[wave]

Thanks KFH.
Good to hear your opinion about the Tung-Sol tubes. I was thinking of getting one of those myself.
Have you considered Eric (tskguy) for you reskin? Eric's current production capsules are looking great. He showed me one the other day that was freshly finished and it was, for lack of a better term, a work of art. F***in beautiful. I'm anxiously awaiting mine!

Dave

 

[ktfstudio]

I,ve been hearing good things about Eric. Thanks for that vote.

 

[pasi_k]

Does anyone have a list of suitable donor bodies?
How about t-bone sct700? for example.
there is plenty of them offered as second-hand.

 

[wave]

Hello fellow builders,
So yesterday I went over to Eric's (tskguy) house. He was kind enough to do some machining to a front panel for a 500 series module racking project I'm doing. We had a period of time where we couldn't run the CNC because of his daughter's nap. So Eric said "sit down and check this out"
He then proceeded  to skin 2 of his HK-67 backplates and then assemble a capsule for me. I had brought my DU67 over so we could do some test recordings shootout style (his DU67 and mine).
First let me say again that his capsules are works of art. To sit and watch while he skinned and tuned them by hand was super cool. We had already done some test recordings of my mic with an ISK K67 capsule in it (I had this from gutting a BM-600 for a DU87 project)
The ISK capsule, for lack of a better description, sounded "Chinesey". Loads of hi mid response - very essey and would probably need some band compression in a mix to sit right.
We then installed his capsule in the mic. It's night and day. The HK-67 sounds absolutely amazing. Rich lows and silky highs with the sweetest midrange. A very good match to my AMI transformer.

I couldn't be happier with my mic. It looks and sounds wonderful - it's a great DIY project. Not something I would recommend for a new builder, but not super difficult either.
If anyone is on the fence about whether or not to invest in one of Eric's capsules, don't be. For $200 it's a steal. You won't be disappointed.

Dave
p.s. For the record, while Eric might be my friend, I wouldn't endorse anything that didn't meet my standards. This is the best compliment I can give.

 

[ktfstudio]

I would have loved to be there. I have always wanted to know what involved in tuning a cap, or a ribbon.  How long did it take?

 

[Delta Sigma]

Waiting on my capsule, body and a few resistors that were back-ordered from Mouser.

In the meantime I thought I'd post a photo of my mostly completed power supply. I made quite a few mistakes on this one since I'm trying to get renos done and when I should be sleeping, I find myself soldering.

I didn't think when I positioned the low voltage transformer and ended up having to turn the IEC housing upside down (no big deal). I then decided just to mount the toroidal transformer to the case (just to get it done), only to find an unused rack ear to mount it to, leaving me with a hole on the side of the case. Lastly, I only realized after I took a photo of this thing, that I put the lamp on the power switch side instead of the mic connector side. If I'm ambitious when I calibrate this thing I move it over.

 

[Delta Sigma]

Since I've made enough mistakes on the power supply, I suppose I should post a photo of my in-progress mic so you guys can set me straight!

Am I on the right track with the hi-Z section? I haven't been reading the forums as close as I should be for this build but I did read that the hi-Z section should be suspended above the circuit board. I did not read the theory on this so I'm not confident that I did it correctly.

I'm waiting on a tube socket and will place the remaining components once the socket and my back-ordered resistors arrive.

 

[Delta Sigma]

Another view of the mic in yet another post. I don't have a clue on how to post multiple pictures in one post.

One more question: I have been using Teflon that I've stripped from wire to insulate the leads of the floating components. Can this cause any problems?

I read on another forum that using solid wire can cause microphonic noise, I assume the writer was referring to the leads to the capsule but they made reference to a stubborn tech that still uses solid Teflon-coated wire in mics even though it's well known that it is not a good choice. The wording they used made me think that the Teflon could also be a problem.

 

[ktfstudio]

I think I read that. Klaus talking about a picture of a mic with solid wire to the capsule!  That is not referring to the mic build itself. I wouldn't worry solid strand in  the hi-z, I didn't. I also have teflon in those positions. Looks to me like your doing fine. But I'm not Klaus. I am trying to decide whether to get a re skin of my k67's or pull the $1400 trigger for Neumann skins because Klaus said there is no substitute. :-X

 

[tskguy]

ktfstudio

By the way I am thee American microphone guru and you should for sure have your capsule reskined by me!! I will do it for the low price of 600 dollars.

I am kidding of coarse but I hope you get my point, Klaus has a good reputation but please keep in my mind your ears are the ultimate decider.  Let me reskin it, I am pretty sure you will be satisfied. PM me I will give you a price. And trust me its way under 1400!!!

tskguy

 

[Delta Sigma]

$1400? If it were me I'd rather do another DU67 build for that much money! I think my total build costs are roughly around $1300 CAD, using the Beesneez capsule. You could put the money you save towards another build using a Beesneez capsule or one from tskguy.

 

[poctop]

Waiting on my capsule, body and a few resistors that were back-ordered from Mouser.

In the meantime I thought I'd post a photo of my mostly completed power supply. I made quite a few mistakes on this one since I'm trying to get renos done and when I should be sleeping, I find myself soldering.

I didn't think when I positioned the low voltage transformer and ended up having to turn the IEC housing upside down (no big deal). I then decided just to mount the toroidal transformer to the case (just to get it done), only to find an unused rack ear to mount it to, leaving me with a hole on the side of the case. Lastly, I only realized after I took a photo of this thing, that I put the lamp on the power switch side instead of the mic connector side. If I'm ambitious when I calibrate this thing I move it over.

Wow very neat build , Kudos,   

it seems you are doing very fine ,
keep on the good work can't wait to see more of those baby's for sure,

Such of a treat for me ,
Thanks ,
Best,
Dan,

 

[dmp]

Built up the mic this weekend. Really a fun project!
I was wondering if a chassis ground connection is required? Should the chassis tab on the xlr be connected to pin 7 or 3? Using a multimeter, 7 and 3 seem to connect on the pcb.
And second question: what size screws are needed for connecting the pcb to the mic body with the cathedral pipes body? I found two that fit to get it together, but I want to order some.
Finally, the mic tube is a tight fit going on with the pcb in (I'm using max's bv12). The body is hitting the bv12. Anyone else have this problem?

 

[poctop]

Built up the mic this weekend. Really a fun project!
I was wondering if a chassis ground connection is required? Should the chassis tab on the xlr be connected to pin 7 or 3? Using a multimeter, 7 and 3 seem to connect on the pcb.
And second question: what size screws are needed for connecting the pcb to the mic body with the cathedral pipes body? I found two that fit to get it together, but I want to order some.
Finally, the mic tube is a tight fit going on with the pcb in (I'm using max's bv12). The body is hitting the bv12. Anyone else have this problem?

pin 7 is 0V and pin 3 the cable and mic body shield  they join to the psu pcb only if SHLF jumper is installed on the pcb if not then you need to connect the shield pin 3 to the mic pcb this permits having 2 diefferent grounding scheme, 
Check the schematic here to better understand 

as per the xlr grounding tab it is already connected to the psu pcb at the connector (XLR-OUT pin 1) and then the PsU pcb 0V connector is to chassis so no need of soldering the chassis tab, 

the transformer should not hit the mic body, check the position of the transformer.

here is the schematic to help

 

[poctop]

regarding the hitting : sometime i had that happen where those screws get a little loose and give the impression that the transfo is stuck in the mic body but it is not ,
hope this helps,

 

[dmp]

pin 7 is 0V and pin 3 the cable and mic body shield  they join to the psu pcb only if SHLF jumper is installed on the pcb if not then you need to connect the shield pin 3 to the mic pcb this permits having 2 diefferent grounding scheme,
Check the schematic here to better understand 

OK - that makes sense. So I can choose to connect 7&3  on the mic pcb by wiring xlr p3 to the pcb (7 and 3 are always connected on the mic pcb) OR not wire p3 to the mic pcb, and install the jumper to connect 7&3 at the psu pcb. Two options for connecting audio ground to chassis ground. The original u67 schematic shows them connecting in the mic, and that p3 is connected to the casing (gehause). How does pin 3 connect to the mic body in this build? The xlr tab I was talking about was the tab on the 7p xlr in the mic. That tab connects to the body.

I did think that the screws on the sides were rubbing, but when I took the mic back apart the copper foil on the transformer had been ripped at the back corners. I'll check it's installation and see if it can go down further.

 

[poctop]

pin 7 is 0V and pin 3 the cable and mic body shield  they join to the psu pcb only if SHLF jumper is installed on the pcb if not then you need to connect the shield pin 3 to the mic pcb this permits having 2 diefferent grounding scheme,
Check the schematic here to better understand 

OK - that makes sense. So I can choose to connect 7&3  on the mic pcb by wiring xlr p3 to the pcb (7 and 3 are always connected on the mic pcb) OR not wire p3 to the mic pcb, and install the jumper to connect 7&3 at the psu pcb. Two options for connecting audio ground to chassis ground. The original u67 schematic shows them connecting in the mic, and that p3 is connected to the casing (gehause). How does pin 3 connect to the mic body in this build? The xlr tab I was talking about was the tab on the 7p xlr in the mic. That tab connects to the body.

I did think that the screws on the sides were rubbing, but when I took the mic back apart the copper foil on the transformer had been ripped at the back corners. I'll check it's installation and see if it can go down further.

How does pin 3 connect to the mic body in this build? The xlr tab I was talking about was the tab on the 7p xlr in the mic. That tab connects to the body.

pin 7 and pin 3  are at the same level on the mic pcb andf the pcb ground plane hook to mic body ,

The xlr tab I was talking about was the tab on the 7p xlr in the mic

it is already grounded via the screw holder

Hope this helps,
Dan,

 

[dmp]

Does anyone know what size screws are needed for connecting the pcb to the mic body with the cathedral pipes body?