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

All New Build guide available trough the website Web and PDF version

Thanks To Steven Jensen For this Build Guide.
available here:
http://www.vintagemicrophonepcbkit.com/DU67.html

I will be receiving next week adaptor pcb for the AMI Classic Series BV12 as well,


Best,
Dan,

Hi All, I am pleased to announce another Transformer Support Options for the D-67 Tube Mic .
this announce and explain how to install the AMI Classic series BV12 to your D-67 PCB Kit,
please request separately with the AMI and external Transformer PCB Kit Style not on web store yet

First , install the transformer with M1.6 screw and nuts , use little plastic washer to make sure the transformer is not in contact with the screw. I haven't put them for the demonstration but use them ,

A) Slide Fit the Transformer in The cutout and screw the adaptor pcb in place




B)  Very Gently snip a little bit of thre plastic corner  Make sure you don't damage the transformer wire close to it ,
Use this kind of precision Snippers,





C) This will looks like this after the Snips


D) Then Close the Shell and it will slide in with no interference at all,



Enjoy and continue your build.

best,
Dan,

Thought I would chime in again and thank-all you guys for amazing projects like this!

My D67 is hands-down my favorite mic! I used a Max Kirscher transformer, and a Sneezby K6.

Here's a link to a recording I did of a great singer and song, on YouTube:

https://www.youtube.com/watch?v=cPUvqEH0_ZE

Chain was D67-->SCA N72 (I think) -->Lavry Blue-->Sonar X2.

Using Lexicon Reverb plug.

Best,

Mike

Hi, quick question for anyone in the know. I have built two of these microphones and they sound great. However I'm finding that in certain places (My Studio) i am picking up noise from the mains power (Lights/LED). The noise is in the form of fizzles and hum, fairly low but audible if your doing voice overs. At my house there is no noise at all. has anyone else encountered this? i have other valve mice in my studio that don't have noise on them, have i just got my grounding wrong?

poctop said:

rjuly said:

Yes, I'm looking forward to getting back to work on my pair. I have looked at my finances, and I can't afford to rectify the error I made ordering the ioaudio bv.12 version pcb's. I am going to try and make them work if possible, with the AMI bv12's. I believe they will just fit in the mic bodies I have. When I drill the holes in the pcb to attach the trafo, should I try to avoid the ground plane or try to intersect it?

Regards,

Rich

Click to expand...

just put a small layer of large heat shrink tube under the core that sit on the pcb ,
that will do it and give a little extra dampening effect,
Best,
Dan,

Click to expand...

I have finally found some time to make a bit of progress on the build of my two mics. I have managed to mount the B12 classics onto the circuit board meant for the T67(since I accidentally ordered the wrong boards). I found some nylon bolts that have worked well:




I now need to make sure that I have the correct connections for my jury rigged build... This is what I think it should be:



Can anyone confirm that I have these connections correct? I understand that the green and yellow need to tied together.

Many Thanks,
Richard

jonathanmorbin said:

Hi, quick question for anyone in the know. I have built two of these microphones and they sound great. However I'm finding that in certain places (My Studio) i am picking up noise from the mains power (Lights/LED). The noise is in the form of fizzles and hum, fairly low but audible if your doing voice overs. At my house there is no noise at all. has anyone else encountered this? i have other valve mice in my studio that don't have noise on them, have i just got my grounding wrong?

Click to expand...

try using ( removing)  the SHLF jumper on the psu and lift the cable shield to see if it helps,
this was  actually  designed for those  scenario where RF issues is present.
hope this helps,

Best,
Dan,

rjuly said:

poctop said:

rjuly said:

Yes, I'm looking forward to getting back to work on my pair. I have looked at my finances, and I can't afford to rectify the error I made ordering the ioaudio bv.12 version pcb's. I am going to try and make them work if possible, with the AMI bv12's. I believe they will just fit in the mic bodies I have. When I drill the holes in the pcb to attach the trafo, should I try to avoid the ground plane or try to intersect it?

Regards,

Rich

Click to expand...

just put a small layer of large heat shrink tube under the core that sit on the pcb ,
that will do it and give a little extra dampening effect,
Best,
Dan,

Click to expand...

I have finally found some time to make a bit of progress on the build of my two mics. I have managed to mount the B12 classics onto the circuit board meant for the T67(since I accidentally ordered the wrong boards). I found some nylon bolts that have worked well:

I now need to make sure that I have the correct connections for my jury rigged build... This is what I think it should be:

Can anyone confirm that I have these connections correct? I understand that the green and yellow need to tied together.

Many Thanks,
Richard

Click to expand...

there is all the information for the pinout of the bv12 directly in the T67 pad on the board,
Actually all the info you need is on the previous page of this thread  , or here

http://www.vintagemicrophonepcbkit.com/D67B/D67B/D-67%20Build%20Guide.html
(end of the page)

I have designed a special adaptor now for the AMI BV12 Classic series.
see here ,


hope this helps,
Best
Dan,

Just taking a look at the PSU build guide on http://www.vintagemicrophonepcbkit.com ... Is anyone else getting blank pages after page 12?

rjuly said:

Just taking a look at the PSU build guide on http://www.vintagemicrophonepcbkit.com ... Is anyone else getting blank pages after page 12?

Click to expand...

yep this is just a formatting error I did not fix yet , but on my plate ,
you are not missing anything so there is no worries,
Thanks for pointing this out ,
best,
dAn ,

I'm building the UK version and was hoping there would be a wiring diag for 220. Also I notice that I am getting 270 AC coming out of the transformer rather than 210. Is that acceptable?

rjuly said:

I'm building the UK version and was hoping there would be a wiring diag for 220. Also I notice that I am getting 270 AC coming out of the transformer rather than 210. Is that acceptable?

Click to expand...

A)  For input transformer toroid the primary needs to be in series for 230V input ,  (see datasheet)
B)  The heater transformer is the same logic see picture in the thread ,  (see datasheet)
C)  Don't worry about the High Voltage until you know what it is with a load,
D) Follow instruction for dummy load in this thread to test psu ,
E.........njoy this part  of the build

hope this helps,
Best,
Dan,

Just got around to finishing a mic a few days ago.  The studio I used to work at had a pair of vintage 67s that sounded a bit different from each other and though I haven't gotten a chance to get back in there to do a direct comparison, the one I built sounds much closer to the one I remember liking more!  It sounds fantastic, and I'm definitely going to order parts for #2 very soon.

I used the tskguy HK67 capsule, AMI T67 transformer, and a silver shield Telefunken EF-86.

The only anomaly in my build was that I had to use a 44k ohm resistor with the B+ trim pot to get 210v, because with 56k I was getting 208v max and with 22k I was getting 216v with the trim all the way down.  Everything else measured fine right away.

Thanks to everyone on the board who made this possible!  You're the best.

Hi guys,
I'm hoping someone might give me some ideas about some trouble I'm having with my mic.

First thing is that I get a "windy" sound which goes down after a couple days of warming up, but is still noticeable even then. I've changed the tube 3 times, and now have a price NOS telefunken in there. The mic sounds great, but that windy sound is pretty annoying. Any ideas?

Another thing I've just noticed seems to be an issue with the pattern switch.
Figure 8 seems fine. When I switch from figure 8 to cardioid, that works fine. Then I switch to omni and the sound shuts out. I still hear handling noise, but it's like the capsules aren't picking up what they're supposed to, or maybe they're cancelling each other out. THEN, if I switch to cardioid from omni, same thing - no real volume to speak of. If I put it back to figure 8, it starts working again, and I can then get cardioid to work again.
weird, huh?
Ideas?

Thank you!

friesdan said:

Another thing I've just noticed seems to be an issue with the pattern switch.
Figure 8 seems fine. When I switch from figure 8 to cardioid, that works fine. Then I switch to omni and the sound shuts out. I still hear handling noise, but it's like the capsules aren't picking up what they're supposed to, or maybe they're cancelling each other out. THEN, if I switch to cardioid from omni, same thing - no real volume to speak of. If I put it back to figure 8, it starts working again, and I can then get cardioid to work again.
weird, huh?
Ideas?

Thank you!

Click to expand...

I came across a similar issue but not quite the same.  I was getting a lot of loud pops when changing patterns, handling noise, low hum, and something I think was the "windy" sound you mentioned, but I double-checked my wiring and found that I somehow forgot to connect the backplate to C2/R2 even though it was wired to the pad switch.  Everything worked after fixing that one connection.  It turned out I was not as thorough as I thought I was.

I'm sure you have already, but go through the build guide again slowly and recheck your connections, especially between the Hi Z network, capsules, and switches .

turned out the connection to the backplate on the capsule had come loose. Thanks for the reply!

I was wondering if any of you have had issues with hum using the mic in some places but not others.  I've been trying to troubleshoot this buzz/hum that's been driving me crazy when I've attempted use the mic at two of the places that I freelance at.  The hum is so loud that the mic is unusable at these places, but elsewhere it's fine.  I've done some experimentation with redoing the ground scheme like connecting pin 3 of the 7 pin XLR to pin 1 of the 3 pin XLR in the PSU, which helps a bit but doesn't get rid of all of the noise. The only thing I do that seems to get rid of the hum completely is to lift the safety ground on the PSU (yikes, I know).  This seems like there is a ground loop inside the mic somewhere. 

For now, I have reset the mic to exactly the way it says to build it in the build guide as a starting point for troubleshooting.

An interesting thing is that with the PSU powered off and my mic preamp gain cranked, I can hear this hum come and go as I move the mic around.  This does not go away when I power the mic on.  Unplugging the 7 pin XLR while the PSU is powered off  however makes the hum go away completely.  Any clue as to where the ground loop in the mic might be coming from?  I'm quite sure I wired it exactly as it says to do it in Dany's guide.

Edit: I wanted to add that the jumper in the PSU to tie/lift pin 3 and 7 has no effect.

So here's an update on the grounding situation.  I've had some time yesterday at the place where the hum issue is the worst to do a bit of soldering.  I've been doing some reading about the "pin 1 problem" and surmised that the mic had that at first, but when I tried tying the output XLR3 pin 1 directly to the chassis and nothing else, the ground hum becomes audibly worse.

Using a pair of headphones , I experimented with connecting/disconnecting different ground schemes using a short wire until I found the one that undisputedly had the lowest audible level of hum.  The cable shield from XLR7 pin 3 is connected to XLR3 pin 1  directly AND to the PCB ground point (see attached picture).This was the result of some trial and error so let me know if any of you experts see anything really wrong with this.

Again, the SHLF jumper in the PSU has no effect on this issue.

Now what was strange is that in certain tie panel inputs is that hum was eliminated almost (if not) completely, but was still quite audible in others.  The XLR tie panels have ground lift switches, but the hum is actually worse when the XLR ground is lifted there.  What still gets rid of the problem 100% is lifting the AC safety ground, which I am not ok with as a permanent solution. 

The noise/hum in the space is clearly audible in DIs as well, which need to be ground lifted in order to get rid of the hum.  The house's Neumann M149 does not have any sort of audible hum whatsoever though. 

Can anyone offer some advice or insight on this issue? It's been driving me crazy for the last few weeks.

here is what the hum/noise sounds in the space sounds like:
https://drive.google.com/file/d/0B1BmrLv1U3XQZzB5cm94Q3UzVWM/view?usp=sharing

Meanwhile in most other places the mic still sounds absolutely wonderful and problem free.  8)

Mrerdat, how is your 7-pin cable wired?

My 7 pin cable is wired the way it says to do so on page 1.

Pin 1: signal +
Pin 2: signal -
Pin 3: shield (I clipped off the black cable and wired just the shield, as per the guide) and it is not connected to the connector shell.
Pin 4: heater
Pin 5: b+
Pin 6: calibration
Pin 7: 0v

Did you attach the shield of the multi-wire cable between XLR7 and XLR3 to ground? Hard to see from your pic. Also just in case, double-check the XLR7 and XLR3 connectors themselves to see if they're properly grounded (worth re-checking all metal to metal contacts are good). Then see if you get a constant ground from the XL3 casing to the GND pin on the IEC, and same to the headbasket of the mic etc.