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

[FarisElek]

What about Start with nothing just for the sake of a baseline  .
D.

Thank makes sense to me since I need to remove it first anyways. That being said, I think I may have jumped the gun. I was only 3-4 hour into burning in at that point, and now I’m around 8 and it’s already sounding so much different. Now I feel like the weird frequency bump that is happening is a little too much 100hz, which may even be the room. It’s still a little dark no doubt, but less so. I’m going to let it burn in a lot longer and then reasses this.

Update:
Definitely jumped the gun. It sounds fantastic. It sounds almost exactly like the D-U87 but creamier and just "better" somehow.

One thing:
If I test all 3 polar patterns about 15 inches away this is what I hear. Cardioid sound brilliant. Figure 8 has a little less volume and seems to be missing some of the high end. Omni seems to be missing some volume and missing the low end. I went in a made sure wires weren't touching leads and tried to clean up the hi-z section a bit but nothing changed. Any ideas?

 

[FarisElek]

Here is a test run through the D-U67. Guitar recorded about 8 inches away from 12th fret and vocals recorded about 8 inches away as well. Both in cardioid. The preamp is Capi VP28 with HPF set on 80hz -6db.  No other processing. I cut it short because I don't know Portuguese and stumble too hard on the other parts of the song. I figure this enough to get an idea what the mic sounds like. The tube after about 14 hours of burning in is sounding nicer and nicer and I don't think I'm going to need to mess with c17 anymore. What do y'all think?

Ryan

https://soundcloud.com/user-368056288/u67-test

 

[Purplenoise]

Here is a test run through the D-U67. Guitar recorded about 8 inches away from 12th fret and vocals recorded about 8 inches away as well. Both in cardioid. The preamp is Capi VP28 with HPF set on 80hz -6db.  No other processing. I cut it short because I don't know Portuguese and stumble too hard on the other parts of the song. I figure this enough to get an idea what the mic sounds like. The tube after about 14 hours of burning in is sounding nicer and nicer and I don't think I'm going to need to mess with c17 anymore. What do y'all think?

Ryan

https://soundcloud.com/user-368056288/u67-test

Sounds nice...sounds right. Of course the vocal is very mellow so it doesn’t stress the mic too much. With louder vocals you’ll get a better idea about the c17 cap...something that sounds perfect with low dynamics might be strident if you hit it harder.

 

[FarisElek]

Thank you purplsenoise for the help! I will experiment with a louder voice. I had my partner sing on through it last night and she got pretty loud and I thought it sounded fantastic, but maybe dark. For now I think it’s perfect. Thank you poctop for the research and PCB. I used to tell myself I’d never have an API board and a u67 to make my homestudio worthwhile and now I have both because of some hard work and the help of the groupdiy.

 

[Purplenoise]

Thank you purplsenoise for the help! I will experiment with a louder voice. I had my partner sing on through it last night and she got pretty loud and I thought it sounded fantastic, but maybe dark. For now I think it’s perfect. Thank you poctop for the research and PCB. I used to tell myself I’d never have an API board and a u67 to make my homestudio worthwhile and now I have both because of some hard work and the help of the groupdiy.

You are very welcome, I ve gotten tons of help from a few members ( and I still do) building my 67’s. I wish someday I’ll get up to their level of expertise...as of now I am still a newbie haha. I am building a 251 now and boy the psu is kickin my arse...

 

[FarisElek]

Just finished tracking my first solo single. I used a host of budget mics originally, but redid the vocals, piano, and acoustic guitar with the u67 yesterday. Mixing last night and this morning, I originally put EQ on all of them but ended up taking them all off after referencing another track. Very crazy. Not used to not needing tons of EQ. All 3 tracks just have  a high-pass via my pre, light compression, and some reverb. The piano I tracked with just the single U67 overhead in Omni for that classic jazz sound. Mind-blown by this circuit.

We also recorded a pedal steel today through a '71 deluxe reverb with the D-U67 and D-U87 positioned on opposite speakers at the same position. At first they were a little hard to tell apart, but during moments when the pedal steel was playing very high or very low in it's register, it became apparent that the 67 had more "air" and a little less low end girth than the 87. In this context we thought the 87 was better, but by a hair.

 

[Purplenoise]

Just finished tracking my first solo single. I used a host of budget mics originally, but redid the vocals, piano, and acoustic guitar with the u67 yesterday. Mixing last night and this morning, I originally put EQ on all of them but ended up taking them all off after referencing another track. Very crazy. Not used to not needing tons of EQ. All 3 tracks just have  a high-pass via my pre, light compression, and some reverb. The piano I tracked with just the single U67 overhead in Omni for that classic jazz sound. Mind-blown by this circuit.

We also recorded a pedal steel today through a '71 deluxe reverb with the D-U67 and D-U87 positioned on opposite speakers at the same position. At first they were a little hard to tell apart, but during moments when the pedal steel was playing very high or very low in it's register, it became apparent that the 67 had more "air" and a little less low end girth than the 87. In this context we thought the 87 was better, but by a hair.

Sounds right, old 87s ( or new with the pad engaged) and 67s sound very similar. 67 sounds a little more compressed, smoother and 3D. You got yourself an awesome mic. Enjoy.

 

[Purplenoise]

So after extensive experimentation and shootouts with the originals I have found that the actual headbasket plays a role too. For those using syt-5 dual mesh the high mids and highs will sound more “crisp” and maaaaybe a little distorted. That has to do with resonances and air dissipation in the headbasket. By adding a third tight mesh or a piece of thin foam it improves sound a lot and brings it even closer to a u67

 

[Reallyjake]

What did you use for the 1uf Electrolytic coupling cap and the gray wilmas?

My mic sounds awesome with Neumann k67 and ami bv12. Letting it burn in now. I’m going to try the Vishay 1839 on my next build. Still waiting on my Neumann bv12 for the next build.
 

Second d67 finished this time most components matching the reissue u67 ( k870, haufe bv12, 1839 Vishay, 1uf Electrolytic coupling cap etc). Kept the carbon film resistors. Works great. I think I might have gotten the “high tension” k870 cause it lacks a little low end compared to the reissue. I’ll let it burn in and change the tube to a Mullard soon.

 

[Purplenoise]

What did you use for the 1uf Electrolytic coupling cap and the gray wilmas?

My mic sounds awesome with Neumann k67 and ami bv12. Letting it burn in now. I’m going to try the Vishay 1839 on my next build. Still waiting on my Neumann bv12 for the next build.

That’s great to hear. The wimas don’t really matter for sound but I went back to the red ones cause I thought it sounded a little harsh compared to my first...maybe just paranoia haha.
I have tried many coupling caps and I ended up with the 1839 for the first and an Illinois electrolytic for the second ( I wanted to keep it as close to the reissue...the Illinois I think sounds better than the nichicon). The best and smoother cap was two wet tantalum 1uf 150v in series but I had some noise and I took them out. One of them was leaky I think.
Something else to try is a thin piece of foam in the headbasket, 3mm 30ppi or 3mm 60ppi. They sell those at air filter supplies. Brings the response even closer to a 67 which has a smaller and 3 layer headbasket.

 

[Reallyjake]

I managed to fit a Mallory cap in this build but just barely. . I have a Solen for the next mic.

I’m happy with the current headbasket being larger. I think I like the open naturalness. I’ll still experiment though.

Hopefully I can post a mix soon.

 

[Purplenoise]

I managed to fit a Mallory cap in this build but just barely. . I have a Solen for the next mic.

I’m happy with the current headbasket being larger. I think I like the open naturalness. I’ll still experiment though.

Hopefully I can post a mix soon.

That’s great, I tried to fit a PIO but it didn’t work haha. As far as the headbasket it will sound great in low levels. If you have a loud vocal it might sound a little edgy because of air dissipation and reflections/resonances inside the headbasket. If you go with 3mm 60ppi you will have no loss in frequency response...just a little padding.

 

[gevermil]

Thats exactly what Im chasing down in my mic .
Neumann cap , Moby xfmr , tele ef86  - but mic has a slight Edgyness to it .
First Ill try the 3mm 60ppi foam as you suggest .
Thanks !

 

[Purplenoise]

Thats exactly what Im chasing down in my mic .
Neumann cap , Moby xfmr , tele ef86  - but mic has a slight Edgyness to it .
First Ill try the 3mm 60ppi foam as you suggest .
Thanks !

Look for air filter foam, I got mine from China on eBay.  On mine this edginess is around 5/6k and then at around 10k. Playing with c17 cap helps also, on mine I have a a value of 150pf. Also post recording if you narrow notch a few db around 10k and boost a 16k shelf it smooths it out a lot. A lot of 67s exhibit this too
The tele is a very clean tube and contributes to that edginess, try a Mullard or amperex bugle boy.
Another little thing to try s to loosen juuuuust a touch the middle screw of the capsule Diaphragm.. Be extremely careful.

 

[gevermil]

great info 
now that I have some time , all those changes will be tried out . Sourcing tube may take a while but I can handle the c17
and eqing .
Loosen the center screw ?!  yikes . Id probably sneeze

 

[poctop]

Loosen the center screw ?!  yikes . Id probably sneeze

mmmmmmmmmmmmm........ InterestinGZZZ.
Best,
Dan,

 

[Purplenoise]

mmmmmmmmmmmmm........ InterestinGZZZ.
Best,
Dan,

Some of the k870 might have high tension on the diaphragm makin them brighter according to klaus Heyne. Since you shouldn’t mess with the screws holding and tensioning the diaphragm the center screw that holds the wire is the only way to relax the diaphragm just a touch. The screw should be still tight and holding the wire firmly so we are talking extremely slight moves.i tried it and it gave the capsule a slight increase in low end and somewhat more tame high mids. If anyone with more experience has something to add to that please advise...I think I came across it at a forum that klaus was participating.

 

[mickdundee63]

Hi guys, trying to trouble shoot my build.

I get a relatively normal sound in cardiod, and the rear diaphragm cancels out as it should. Omni also seems ok. In figure 8 the rear side sounds normal but the front side is very thin, like there's an aggressive high pass filter on it. It also seems to have a low output generally in cardiod and omni (compared to my first successful build) and I'm getting some interference noises from the computer which I've heard on other mics which have had grounding problems (and were fixed by addressing the grounding issue).

When I put it into figure 8, sometimes it makes some loud thumping noises for a few seconds as well.

Heater and B+ are in range, I've had a good look around and cleaned things up, but no luck, wondering the best place to start troubleshooting. I have my previous build as well which is helpful for comparison, but haven't turned up anything so far.

 

[Reallyjake]

I’m having the same issue. It helped to lower both voltages.  I also checked inside the mic to make sure nothing was shorting to the mic frame. I’m trying a new tube after Memorial Day and will report back.

 

[teambanzai]

I am definitely late to the party, but is there any chance of a restock on the PCB sets for this build?