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

...that RK-47 capsule is far from dark on it's own...IMHO, probably the brightest of the aftermarket K47 capsule options...

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Yes, likely because of its 3 micron thickness.
But still.

Frequency response in this link:
http://microphone-parts.com/rk47-microphone-capsule/

And that's without de-emphasis.

dmp said:

So the adjustment for the Plate voltage is R3 (8.2k) -> 56k -> 50k pot where the 56k is hanging off the pot? Why not just use 68k for R3?
Also I feel like I may be missing a key part of the build info? I've been looking through a ton of pictures, the BOM, and the schematics. But didn't see anything about the 56k until reading through the thread again this morning. Is there another schematic I've missed?
Also, note that the PT for the B+ should be wired parallel primary, series secondary. I made that mistake as well until seeing the sketch on page2 of the thread.

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Yes you are correct both is better to have a resitor off board to be able to swap it and adjust the voltage drop for different transformer so once in the ball park you tweak with the pot,
depending on your country 230-115 you need to take in consideration at the primary and the secondary might also depends if you multiple out put.
hope this helps, 
dan, 

Any chance will have to see some completed mic before the end of the world (21 dec-2012),  ;D
just a toughts, 
happy building still, 
Best, ;D
Dan,

Hey Dan!
I really, really love your D-u67 its the perfect tube mic out there!
Real tube sweetness, detailed and full sound!
I told you i wasnt building one but hey you made me change my mind when i heard yours!

Nice body by chuckD too!

In testing the U67 with RK-47 in it along side a C12 style with a RK-12 in it, yes it did seem a little muffled on the top end, have changed to a R-67 and sounds much better but valve seems to have this wind sound, getting a winged C nos EF86 valve next week, so will hopefully be quiet as a mouse now so i can properly test.
Prelim tests agains C12 on vocals is the C12 wins, but on acoustic guitar the U67 is amazing, really articulate.
did a room mic on drums with the U67 and it sounded great.
Cant wait to get my U47FET version going as putting on kick drum, just need to finish design of U47 style mic body which will have also have 2nd head basket U67 style so i can have a pair of U67's for room mics.

And this is hopefully gonna be the U47 style body. I'll post some real pics of the insides and outsides once both types have been made.
Both may also have the option of having a different sleeve with holes in the top for switches.

hey - are you going to offer these mic bodys?

In testing the U67 with RK-47 in it along side a C12 style with a RK-12 in it, yes it did seem a little muffled on the top end, have changed to a R-67 and sounds much better

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Yeah, that's what I figured. Thanks for the feedback.

Two nice babies for the locker there. Keep us posted, please.

Hi,

if enough people were interested in these bodies and the price was right im sure we could do something, gonna take a couple of weeks to go through all the nitty gritty stuff and get it all sorted. I want them to be all interchangeable, so you could have:

1. U47 body + U47 Style head basket with U47 or U47 FET pcbs inside.
2. U47 Body + U47 Style head basket with cutaways for switches with U47, U47FET, U67 or U87 pcbs inside
3. U47 Body + U67 Style head basket with which ever one.

you get the idea, rather than write out every permutation im sure you can decide which would suit you, would be interested in comments and feedback from everyone.

Hi Guys,

just thought i'd post a picture of the proposed versions with switches.
These are only really ruff, but you get the idea.

regards

Spence.

Rear View.

Here is a bit to share...After burning in 2 tubes in my stereo pair for a week straight, I found the (previously favored) Tungsol tube to be popping. AND the previously disapproved of Telefunken silver shield tube to be the new champ. So tonight I installed the other ( formally disapproved of) Tele tube from the matched pair that I bought and started to sweep the voltages. I brought the filament V up to 9v and down to 5v, and swept the plate up and down as far as it would go. I noticed a improvement in that tube. (less noise) Now, in three or four days, I hope to see a settling out like the other Telefunken tube. The conclusion...there is a burn in period that can't be ignored. This a delicate circuit that will take some time to get right, but it's totally worth it. This mic, even in it's infancy, rocks.
Also what might be happening here is the PSU needs to be burned in so that the plate voltage remains stable. Turn your monitors down when sweeping the plate. 1 volt will send your speaker into DC land.
Cheers

Where did you get your tele's from if you don't mind?
Interesting about the tungsol's and to see whether the tele settles in after a while.

Cheers,
jb

Anyone tried a Beezneez K67 Capsule yet, just wandering how they react on this ,
Let me know if anything ,
Best,

I just tried a "matched set NOS" from ebay. Most the ebay listings are from Germany. I thought I had two noisy tubes and I was looking for another source. There is a seller in Turkey that will work with you and will take back tubes that prove unacceptable but you have to pay shipping. And they are about $80. I think I got my pair for about 35 dollars but without the return option. Just google telefunken ef86 and he should be close to the top.

Ben has been trying to save his daughter and not sending out any of his online orders. I have an order that is about six weeks old. I keep trying to get updates about her condition but nothing yet. I know he went stateside and I don't know if he's here or in Australia.

I bought a Telefunken "Hilumin" EF86 from www.nostubestore.com and picked up a Valvo EF86 for a spare. I did a little searching for info on what the best suited EF86 for mics is and found this: http://prorecordingworkshop.lefora.com/2011/02/06/ef-86-manufacturer-recommendations/

I don't have a capsule yet (ordered the Beesneez) or a body so I haven't tried either tube but Koray @ nostubestore was great to deal with.

@ktfstudio

Ben is sending out his online orders as far as I understand. Both danderloo and winetree confirmed they received their capsules on the Beesneez White Pages thread. Ben had brought a bunch of capsules with him to the states to skin and ship so I'm hoping mine is somewhere in the hands of USPS or Canada Post now.

That's good news, maybe mine is in route too. Hope this means his daughter pulled through!

hi all,

this is very interesting about the valve issue, i got a Tung Sol  and had this wind noise at low level, i first changed the capsule and the wind noise was still there, i then sent it back and got another from karltone on ebay,  it is a winged C EF86, wind noise reduced but still there at low level, i say wind noise but its a combo of wind and bubbling.
You guys mention adjusting voltage, do you mean the other pot in the power supply?
as i was under the impression this was the heater voltage?
just wanted to be clear, i will give this a tweak to see if i can get rid of this noise, rather than plug it all into my monitors i think i'll do it into a small mixer on headphones.
could it be a noisey resistor?
any other help solving this noise issue would be great.

Spencerleehorton said:

Hi,

if enough people were interested in these bodies and the price was right im sure we could do something, gonna take a couple of weeks to go through all the nitty gritty stuff and get it all sorted. I want them to be all interchangeable, so you could have:

1. U47 body + U47 Style head basket with U47 or U47 FET pcbs inside.
2. U47 Body + U47 Style head basket with cutaways for switches with U47, U47FET, U67 or U87 pcbs inside
3. U47 Body + U67 Style head basket with which ever one.

you get the idea, rather than write out every permutation im sure you can decide which would suit you, would be interested in comments and feedback from everyone.

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Spencer Lee .. Gotta admit I'm Jonesying on those nice looking U47 bodies   

It might be worth starting a separate Feeler thread to gauge how much interest you can get. Have you gauged a price level yet? 

Cheers

No price level on the mic bodies yet, but I am planning for them to be cheaper than anything else out there, if there are enough orders, maybe in orders of 10 or 20 they could work out really reasonable. at a guess im aiming around about $250/£150 for one body, but i'd like to do it as a kit so you can order what head basket you want, what insides you want, and whether you want holes for switches or not.
will try and put another thread up about it when im a bit further to building them.
Everything is in CAD world at the moment!!!

Spence.