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

[EarthTone]

Yes you can.
People actually praise the 797 K67 capsules, there's a lot of fans of those capsules around here.
I actually bought 4 of them directly from 797, still haven't use them, but I will also use them in some U67 builds.

If you use them and you like the sound don't stress about having a vintage Neumann capsule, a vintage capsule might haven't aged that well, and if you like the sound of the 797 it's because it's good and a good reason to leave it be.

Thank you! Yes I have in the past used the C1’s with these capsules 797 k67 to record different types of instruments & voices and I like them! I have done the Micparts HF rolloff circuit mod on mine. But I find the sound of the clean circuits a bit boring, so was thinking that this might be a really fun project to use these 797 K67 capsules in. It seems like a good choice. Thanks again.

 

[EarthTone]

Yes you can.
People actually praise the 797 K67 capsules, there's a lot of fans of those capsules around here.
I actually bought 4 of them directly from 797, still haven't use them, but I will also use them in some U67 builds.

If you use them and you like the sound don't stress about having a vintage Neumann capsule, a vintage capsule might haven't aged that well, and if you like the sound of the 797 it's because it's good and a good reason to leave it be.

Thank you! Sounds great.

Yes you can.
People actually praise the 797 K67 capsules, there's a lot of fans of those capsules around here.
I actually bought 4 of them directly from 797, still haven't use them, but I will also use them in some U67 builds.

If you use them and you like the sound don't stress about having a vintage Neumann capsule, a vintage capsule might haven't aged that well, and if you like the sound of the 797 it's because it's good and a good reason to leave it be.

Shoot, actually it appears those are not the capsules I have. I used stock photos above, and I thought that’s what would be un my mics but they’re not. This is what’s in my Studio Projects C1’s. It looks like they only have one side? And only 2 wires. Cardioid only right? What capsule is this? Can I still use it in the u67 or will it only have one pattern?

Matt

 

[Whoops]

It looks like they only have one side? And only 2 wires. Cardioid only right? What capsule is this? Can I still use it in the u67 or will it only have one pattern?

Matt

yes that capsule is a single diaphragm, cardioid only.
You need a double diaphragm for the U67.

The correct capsule from 797 is the CY002 model, you can order directly from them it’s pretty cheap .

 

[C12VR]

Hi guys
The mic sounds great with a chinese edge terminated capsule, but I am having a hum issue with my build. I know it's probably a filtering issue because when I turn the dimmer switch which is unfortunately wired into my basement, the hum gets noticeably worse at certain levels. I have a DEF-47 and that is whisper quiet, so it's something to do with this particular mic. There is continuity between all exposed metal and 0v is star grounded to the IEC ground. Hum level is high enough to be noticeable with a moderately loud acoustic guitar. Is this normal, and if so, can it be fixed by increasing PSU filtering? the H- supply has at least 20mv of ripple according to a PSUD2 simulation. If not, what's the issue?

 

[dmp]

Is this normal,

No

can it be fixed by increasing PSU filtering?

No, the filtering should be sufficient (unless you made a mistake). You are picking up interference, the way a single coil guitar will pick it up. I have recessed lights with a dimmer and they need to be off to play my tele.
Properly built mic should reject the noise. You have to troubleshoot the grounding and shielding. Check how the audio ground is connected to chassis ground (is the audio ground connected to the mic body, in the mic?), the cable shield connection (both ends), SHLF jumper, etc...
If everything is built to spec, then note that Danny's PCB didn't implement the Neumann ground scheme correctly. There are some posts in this thread talking about it.

 

[Delta Sigma]

could be a ground loop. at how many points and where is your 0V bus grounded to the chassis inside the PSU?

 

[dmp]

There is continuity between all exposed metal and 0v is star grounded to the IEC ground.

Before you do anything else make sure the mic body has continuity to the IEC ground with the power off.

 

[dmp]

Some posts about ground scheme starting here

 

[C12VR]

Before you do anything else make sure the mic body has continuity to the IEC ground with the power off.

Yes I got that, thank you. Will troubleshoot in the meantime.

 

[Greenie]

Hi. Are these to switches basically the same?

 

[Whoops]

Hi. Are these to switches basically the same?

I'm not really sure what you mean, can you explain it better?

The Blue PCB on the right has 3 switches, one for Polar Pattern change (3 positions), other for attenuation PAD and another to activate and High Pass filter, these last two are just 2 position switch (or ON/OFF I suppose)

The 3 position Polar Pattern switch, the one that says "PAT" in the blue pcb is equivalent in terms of function to the Pattern switch on the Neumann part on the left.

 

[Greenie]

These two have the same way of the internal switching of the mic? so if I need to use the blue board instead of the other switch, that would be the same? Ther are seven option in all, with the on / off counting as two. and the directional (omni etc.) as three? I need to figure out how two use the blue pcb in a mi that was meant for the other?

 

[Whoops]

I need to figure out how two use the blue pcb in a mi that was meant for the other?

There’s 3 switches in the Neumann head also, the polar pattern at the front and the other 2 in the back.
You have to follow the schematic then it would be really clear how to wire the blue board instead of the Neumann head. It’s pretty simple and obvious once you follow the schematic

 

[Greenie]

There’s 3 switches in the Neumann head also, the polar pattern at the front and the other 2 in the back.
You have to follow the schematic then it would be really clear how to wire the blue board instead of the Neumann head. It’s pretty simple and obvious once you follow the schematic

Ok, so it's the same, thank you, just needed confirmation...

 

[Whoops]

Ok, so it's the same, thank you, just needed confirmation...

Yes the same, just the switch type is different.

 

[Daniel Faustino]

Hello guys,
Which kind of resistor did you used in series with the trim pot, the 56k one? I mean in power handling (1/4w, 1/2w, etc)?

 

[klem]

I used a 1W, Mouser 66-CMO15602JLFTR

 

[Daniel Faustino]

I used a 1W, Mouser 66-CMO15602JLFTR

Thanks!

 

[klem]

cheers. of course, someone else please correct me if i'm wrong with needing a higher wattage. i've yet to finish the mic portion of the build so can't swear by it for long term use, but no smoke has arisen from the powered on PSU for initial testing
that's also the part numb in Dan's BOM

 

[Daniel Faustino]

Yes, of course!
No smoke is always a good sign! Ahah