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

[DUDE GUY]

Hello,

I finished my U67 recently. It sounds great, works fine, but seems slightly dull to me. Is this normal?

RK67 capsule
BV12 transformer

Having no experience with a real U67, I'm wondering if this is the way it should sound or if I'm way off. I didn't do any kind of calibration, is there a calibration process other than the frequency response test described in the manual?

Any help is appreciated. Thanks.

-Kevin

 

[wave]

The real 67s that we have used and shot out with were def not dull. You got any sound samples?

Dave

 

[poctop]

The D-U67 is the most sparkling mic I have, it sounds like like a U87 on steroid with that tube sounds in bonus ,  to answer your question I guess it would be best to let chime in the folks that actually have built one and could comment on it. there is many sound sample trough the thread also

here is one of many, Thanks to Sylvain.

ok here is finally a comparaison between classic U67 and my D67 at mythic studio gang paris
i did a little article (english) on my blog with the audio files there and building pictures (in french)
hope to do more but that's it for now
massive thx to poctop this is a great kit !

http://www.sylvainmoreau.com/sylvain_moreau/?p=940 (http://www.sylvainmoreau.com/sylvain_moreau/?p=940)
(say hello in comments )

thanks to Dave,

Hello all,
I just wanted to share my thoughts on the DU67 project. I LOVE this mic. It's super sweet and sounds absolutely awesome.
Tskguy's capsules are truly works of art. Here are some tracks I threw together while doing some initial recordings after finishing the mic and installing on of Eric's capsules.
The signal flow is DU67 –> Sound Skulptor MP573 –> ProTools. I'm really digging the way these tracks sound with no eq or comp.
2 acoustic guitars and 2 vox

https://cdn.groupbuilder.com/groupdiy/u/39511/58d0281993f40.wav

I did this in about 10 min single takes on all the tracks so I'm sorry about my pitchy vox.
This mic is def going to be on all my records from now on and it's already at a colleague's studio doing the duty!

Dave

Best,
Dan,

 

[ben_studio]

Dear all,
I've finished last june the D67, works great, but I've been concerned the last couple of weeks by the sound of it and I Guess it's probably coming from the tube, which is a TELEFUNKEN EF86. When a singer sings into the mic without a PopKiller, sometimes the mic' starts doing a heavy unwanted sound, crackles a little bit, and then calm down again after 5/10sec. It's similar as the noise we can hear when we start using the mic the first seconds, while the tube is warming up.
Anyone is aware of this kind of trouble or is this my tube which is non working fine ?

I've also noticed, that at equivalent recording levels, my D67 does have a floor noise higher than a TLM103 for e.g. Is this also normal that the D67 is not "as quiet" a Neumann TLM ? (which has no tube inside)

Let me know your thoughts about this,

Thanks

Ben

 

[0dbfs]

Hi Ben, these symptoms sound like you may have a microscopic or larger hole in the diaphragm. Or the diaphragm has become overly contaminated with debris or other foreign material.

You can do the breath test (easy to do anytime. Just search it of you are not familiar) as well as investigating with a magnifying glass.

If one side is damaged and you usually use cardioid you may be able to turn the capsule around and retire so your not using the damaged side.

Cheers,
Jonathan

 

[poctop]

Hi Ben, these symptoms sound like you may have a microscopic or larger hole in the diaphragm. Or the diaphragm has become overly contaminated with debris or other foreign material.

You can do the breath test (easy to do anytime. Just search it of you are not familiar) as well as investigating with a magnifying glass.

If one side is damaged and you usually use cardioid you may be able to turn the capsule around and retire so your not using the damaged side.

Cheers,
Jonathan

Thanks JB, this is exactely what i had in mind , and to answer your noise question the noise is directly dependant on the tube used,  in "general" tube mic are a tad noisier than tranformer-less - microphone without tube but it depends also if it is hum or hiss (with noise) and at wich level it becomes abnormal
Best,
dan,

 

[ben_studio]

Thanks to both of you for your answers.

I've been doing the same tests with Sylvain Moreau this afternoon on his mic, and regarding the sound produced after a "p" sound for example (that would be also really close to it, like 2cm) he noticed exactly the same problem.
I would really go into a tube issue as this sound of "vynil hum" I can hear it when the mic is warming up (and before singing into it)

I don't think (well I hope) our two capsules are not down or presenting a small problem, but in case, I'll probably try to reverse the side as suggested.

Regarding the noise, it's not a hiss noise, it's really like there's more 'white noise' in the tube Mic than in the FET, but as you said it's probably a characteristic of tube Mic.

I'll try to make 2 recordings to make you hear the differences, and in the same time, will soon post a few vocals and cellos I've been doing for future builders !

Thanks again

Ben

 

[poctop]

I've been doing the same tests with Sylvain Moreau this afternoon on his mic, and regarding the sound produced after a "p" sound for example (that would be also really close to it, like 2cm) he noticed exactly the same problem.

could you ellaborate on this what is the issue with the p sound does it pop the diaphrgame out , just curious are you using a pop filter and also is your S2 internal switch  jumpered for "bass proximity"
also wich capsule are you using?

Let me know,
Best,
dAN, '

 

[wave]

Dany,
That is def the best way to show how the mics should sound! I had forgotten about that lil test track I did.
I still think it sounds amazing.

Kevin,
Do you have any sound samples you can share with us? I'm interested to hear what your mic sounds like. I had an RK-67 in my D-U67 initially and it was def not as good sounding as my HK-67 (Heiserman Audio).
I am def a proponent of 80% of the mic's sound is in the capsule

just my 2¢
Dave

 

[0dbfs]

Hey Ben, the breath test is easy to do by exhaling slowly close to the head basket directly into the capsule (not popping it). So that the capsule gets a slow-and-humid breath all over it. It shouldn't cut out or make wind noises in that case unless the humidity is causing small shorts between the backplate and sputtering or if there is a hole and the humidity is condensing in between the backplate and membrane/hole. It dries itself within a couple seconds with this test.

Popping it can do the same thing but you want to listen when exposed to slow-breath-high-humidity.

Cheers,
Jonathan

 

[ben_studio]

Hey Ben, the breath test is easy to do by exhaling slowly close to the head basket directly into the capsule (not popping it). So that the capsule gets a slow-and-humid breath all over it. It shouldn't cut out or make wind noises in that case unless the humidity is causing small shorts between the backplate and sputtering or if there is a hole and the humidity is condensing in between the backplate and membrane/hole. It dries itself within a couple seconds with this test.

Popping it can do the same thing but you want to listen when exposed to slow-breath-high-humidity.

Cheers,
Jonathan

Dear Jonathan,
It seems in fact that with the breath test, it produces a noise growing up as described before, and I found out the other side of the capsule (in bidirectional mode for testing) seems to work better and the sound is even louder.
I can't physically turn around the capsule, so do you think I can disconnect and switch the wires on the capsule to use the other side when I'll be in Cardiod position ?
I mean, take the wire fixed on the damaged side, unscrew it, and screw it back to the other side ?

thanks

Ben

 

[0dbfs]

Ben, don't unscrew the wires from the capsule. It is not recommended in any case unless you don't particularly want to use it anymore.

Instead you should desolder the front/back wires from down in the hi-z section and reverse them.

Be very careful to cover the capsule with a loose plastic Baggie or something to protect it while soldering. A tiny hot blob of vaporized flux will melt a tiny hole in the diaphragm pretty easily.

I would also take the opportunity to visually inspect the capsule for damage or other foreign material contamination to confirm our suspicions of what the breath-test appears to have suggested.

Cheers,
Jonathan

 

[ben_studio]

Ben, don't unscrew the wires from the capsule. It is not recommended in any case unless you don't particularly want to use it anymore.

Instead you should desolder the front/back wires from down in the hi-z section and reverse them.

Be very careful to cover the capsule with a loose plastic Baggie or something to protect it while soldering. A tiny hot blob of vaporized flux will melt a tiny hole in the diaphragm pretty easily.

I would also take the opportunity to visually inspect the capsule for damage or other foreign material contamination to confirm our suspicions of what the breath-test appears to have suggested.

Cheers,
Jonathan

Dear again,
Here is the sound before I Fixed the problem :
http://benoitlaur.com/soundonline/
Click on file 'd67 exhaling'

I did the changes of the wires from back to front, (with extreme care on the capsule well protected of course)
The sound is better, and when I do the exhaling test again on the new good side, it does not produce any more 'huming' or anything you could hear on the file I recorded before.
So I guess one side of the capsule might have been damaged, I'll join photos, but I'm not sure you can actually notice especial on it.

Thanks again, this was as you said not a "tube problem"

Ben

 

[ben_studio]

Ben, don't unscrew the wires from the capsule. It is not recommended in any case unless you don't particularly want to use it anymore.

Instead you should desolder the front/back wires from down in the hi-z section and reverse them.

Be very careful to cover the capsule with a loose plastic Baggie or something to protect it while soldering. A tiny hot blob of vaporized flux will melt a tiny hole in the diaphragm pretty easily.

I would also take the opportunity to visually inspect the capsule for damage or other foreign material contamination to confirm our suspicions of what the breath-test appears to have suggested.

Cheers,
Jonathan

And here is the link with the 2 pictures of both sides :
http://benoitlaur.com/pictureonline/

 

[gary o]

Hi what is the 270P for thats not in the BOM thanks ...

 

[poctop]

Hi what is the 270P for thats not in the BOM thanks ...

it is for the low cut/pad section operation in the D-269c and the D-67

the 270 pf/630V  polystyrene is difficult to find that is why i supply complimentary kit trough the webstore for the mic projects,
this is also true for all the mic project i host on groupdiy,

what we generally found as polystyrene is 50V and it is not enough to survive long in the mics,

hope this helps,
Best,
dAN,

 

[gary o]

Thanks for info so its C10 ? its not on your schematic on original schematic its 500pf does smaller value pad down less, thanks again...

 

[poctop]

Thanks for info so its C10 ? its not on your schematic on original schematic its 500pf does smaller value pad down less, thanks again...

there were tiny difference over the year , here is 2 schematic showing the use of the 500pf and the 270pf and also 400M over 500M and 60M over 68M,  might also be the availability of the parts also,
I beleive that the mic was too hot when it came out early 60s for the US gear and then the pad cap value was modified over the years also the 500M and the 400M were used interchangeably, this value will affect the pad efficiency and broadcasting quality related to how the low end behaves. it can be swapped and tryed out for sure.

hope this helps,
Dan,

 

[gary o]

How interesting thanks  , I see 1uf C9 too, I came across a schematics showing no C17 too

great info big thanks

 

[Melodeath00]

Any guesses why they changed C9 in terms of both value, and voltage rating? First one is 250V and the next is 450V. Also not seeing a date/year on those schematics