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

[Lordward]

All three can be both type.

Cheers, I now see that it's 2 x 2 positions and 1 x 3 position.....makes sense

 

[Lordward]

Regarding the PSU in a 230V country, am I correct in assuming that I can use this part (Hammond 186C20) for the 20VAC by connecting pins 2&3 (for 230V) and pins 5&8 to the PCB  AC in 20V? 

http://www.mouser.de/ProductDetail/Hammond-Manufacturing/186C20/?qs=sGAEpiMZZMvwUzoUXIIvyQPvPmwnNFGyFP5siSHDz8Q%3d

 

[Lordward]

Still hoping for a bit of help here.  I've complete my build and I'm having some issues at calibration.
For a start I measured the PSU, mic  not connected, and I get the following values:

Heater = 22VAC
AC In 210 = 270VAC

B+ = 227 DC
H- = -17.77
-----------

Mic plugged in, no tube:
B+ = 249
H- = -17.66

0.9 Ohm  between the mic body and the chassis of the PSU
---------------

Right after measuring my PSU gave out.  It kept blowing fuses and the last fuse I put in I could smell a bit of electrical burn.
I took out the PCB and could see that D1, the 15 V 5W Zener diode  has burnt out.
What could the reason for this be? 

Cheers,
Dennis

 

[Lordward]

Anyone?  :-X

 

[3nity]

hi guys im slowly getting into this project!
I was wondering if this transformer would work for psu!
http://www.antekinc.com/as-05t240-50va-240v-transformer/

 

[wave]

Anyone?  :-X

Was your diode installed correctly?
You need the load of the tube to get your voltages to sit better.
Can you post a pic of your PSU wiring?

Dave

 

[wave]

hi guys im slowly getting into this project!
I was wondering if this transformer would work for psu!
http://www.antekinc.com/as-05t240-50va-240v-transformer/

This will work but it's a bit overkill. Any reason you are looking at this transformer?

Dave

 

[3nity]

Hi wave,
I just dont wanna have 2 transfos inside the psu.
also maybe i build a second one!

 

[Kraume]

So i just ordered everything and be very excited to start soon with this new project.

There is just one thing i'm wondering about: The Mouser Boom holds a 0.3A fuse. The first Page mentions  0.1A and 0.2A. What do i need in Europe using this transformer. http://www.mouser.de/Search/ProductDetail.aspx?R=FS20-300virtualkey55310000virtualkey553-FS20-300

Thx and Greets
Lars

 

[TLRT]

I'm using 0,315A fuses without any issues in my builds

So i just ordered everything and be very excited to start soon with this new project.

There is just one thing i'm wondering about: The Mouser Boom holds a 0.3A fuse. The first Page mentions  0.1A and 0.2A. What do i need in Europe using this transformer. http://www.mouser.de/Search/ProductDetail.aspx?R=FS20-300virtualkey55310000virtualkey553-FS20-300

Thx and Greets
Lars

 

[shewhorn]

... i remember reading a document called the Pin 1 Problem in regard to driving different equipement on realted ground without having issue and the need of a ground lift very interesting article , i am really glad you made this point ,

Those articles were from RANE, they published two notes on the subject. The official AES 48 standard as it pertains to the shield on mic cables is for pin 1 to connect to the chassis otherwise you run the risk of taking interference that is traveling along the shield and introducing it into your signal path (if I'm understanding things correctly). Here's the links to the RANE Notes:

RANE Note 15 1 - "Grounding and Shielding Audio Devices":
http://www.rane.com/note151.html

RANE Note 165 - "Pin 1 Revisited":
http://www.rane.com/note165.html

 

[shewhorn]

I'm in the process of doing all of the research for this build. I have some issues with reading so... parsing a 59 page thread is a little daunting. I'm wondering if anyone who has recently done this build can help me out? Here's my understanding of what I need:

All 5 items from the PCB-D-67 kit from this page $89:
http://www.vintagemicrophonepcbkit.com/orders.html

This mic body kit from Studio 939 (SYT-5 Gen 3) $145:
http://store.studio939.com/product/syt-5-microphone-body-kit

The components for the microphone from this BOM $45.05:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=83ad963d23

Now, here's the first problem, the Vishay 0.47uF cap is obsolete. None of the equivalent options are in the same package. What is everyone using for that? I've narrowed the field down in the following link. Looks like the Wima and the Nichicon caps are the closest matches but neither are the same form as the Vishay. Will they work in this build? The Wima doesn't even have bendable leads... could solder some leads to it but... still, tight spaces etc. What is everyone else doing?

http://www.mouser.com/Passive-Components/Capacitors/Film-Capacitors/_/N-9x371Zscv7?P=1ywtgmbZ1yznbzsZ1z0wquaZ1yzs9nv&FS=True

The components for the PSU from this BOM ****MINUS THE CASE**** $95.38:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b5c122b4d0

This case from Collective Cases $65:
http://collectivecases.com/?product=psu-cases

An HK67 Capsule from Heiserman Audio $250:
http://www.heisermanaudio.com/store/p4/Heiserman_HK67_Capsule.html

AMI T67 Transformer from Zen Pro Audio $110:
http://www.zenproaudio.com/tab-funkenwerk-ami-t67-transformer

Amerpex EF86 Tube $99.95:
https://tubedepot.com/products/amperex-ef86-6267

Total cost: $899.37 (plus some shipping charges I'm sure)

Is there anything I'm missing?

 

[dmp]

If it's your first build, you might want a cheap capsule and tube to use until the mic is done

For the plate cap, try out the search function at mouser. Use the search fields to narrow it down.
I just did it quickly - start out by going into "film" capacitors, because that is the type you want.
You want an axial cap, 0.47 uf, 250v or more, and "in stock"
This brings you down to about 40 options.  You can check the length & diameter against the PCB to make sure it will fit. 
Then you can look for brands / series. Cornell Dubilier and Vishay will be high quality choices - the series 150 by Cornell is pretty frequently used in tube audio, for example (539-150474K630RF).
You can always order more than one to try them out. As long as they are rated >250v they will be a safe sub.
WIMA are really good but they don't come in the form factor you want so I personally would go with an axial cap.

 

[Delta Sigma]

The components for the PSU from this BOM ****MINUS THE CASE**** $95.38:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b5c122b4d0

When I built mine I hesitated on the Mouser order then somehow lost my cart. I re-filled it from the BOMs and forgot to "MINUS THE CASE"! Oops. I used the Collective Cases case for my 67 then somehow crammed my M49b PS into that Hammond case.

I replaced my output cap with a NOS Metallized Paper cap from Ebay. Add overseas shipping and buying multiples and it'll be  more than a film cap from Mouser. With the amount that a nice output cap can colour the sound it's worth buying both.

Personally I'd buy tubes from Bowie. I don't know if I trust most vacuum tube sites any more than Ebay. Not that they're trying to pull a fast one it's just that they're targeted toward Hi-fi and guitar amps, not microphones.

Before I knew about Bowie I bought my EF86 here but they're sold out of the Silver Hilumen.

 

[shewhorn]

If it's your first build, you might want a cheap capsule and tube to use until the mic is done

Thanks for the feedback! Great advice, fortunately it's not my first mic build. Two months ago I built a Microphone-Parts S3-87. Super easy build, worked the first time! This one is obviously a little more involved but in terms of assembly, it doesn't look terribly difficult. For me the difficulty with this build is just figuring out everything I need. By the time I do this build, I'll also have 6 Seventh Circle Audio pres under my belt. I anticipate those being easy... all through-hole stuff with the exception of two IC's on the C84s which are surface mount. I bought a great little surface mount practice kit from Amazon and it was much easier than I remembered it being (a while back I used to do software testing and engineering for a few pro audio companies which had me doing very basic surface mount work on the rare occasion).

For the plate cap, try out the search function at mouser.  Use the search fields to narrow it down.

That's what the above posted link did. There were only two matches for a 0.47uF PolyPro, RF Microwave Film,  250 VDC, 10% tolerance cap which were the Wima and the Nichicon. If I remove the requirement for RF uWave film, the options open up a bit and I can see the Cornell caps you mentioned which weren't visible in my previous search. I'd say I do well at the assembly side of things, but my knowledge with regards to how a particular cap is going to affect the sound quality is pretty minimal. Looking at the Cornell caps, the 930 series seemed to be the closest match to the original spec:

http://www.mouser.com/ProductDetail/Cornell-Dubilier/930C2P47K-F/

And then here's the 150 series you mentioned:
http://www.mouser.com/ProductDetail/Cornell-Dubilier/150474K250HC/

Finally a Vishay:
http://www.mouser.com/ProductDetail/Vishay-Roederstein/MKP1845447255/

Is there any science behind determining which of those would sound the best or does it come down to trying it in the circuit and hearing how it sounds?

 

[shewhorn]

Personally I'd buy tubes from Bowie. I don't know if I trust most vacuum tube sites any more than Ebay. Not that they're trying to pull a fast one it's just that they're targeted toward Hi-fi and guitar amps, not microphones.

Before I knew about Bowie I bought my EF86 here but they're sold out of the Silver Hilumen.

Thanks... looks like his addy is [email protected], no website. As a side note... that Amperex tube I listed, I wasn't looking for this info specifically but in doing another search, I stumbled across this:

http://www.neumann.com/forums/view.php?bn=neumann_archive&key=1015336865&v=f

Looks like the Amperex 6084 is worth looking at too.

 

[tonitu]

Hi, I´ve some problem with the Mic, maybe someone can help me.
The PSU is working right.  B+ W/O load I reach 240/250 (depends on line, but I can Trim), and -16 in H-.
When I connect the mic without the valve I had the same, measured in the mic (240/-16)
I put the valve (I´ve tried tree different valves) ef86, and I can adjust the tension on B+ to 210v and in H- to -6.1v
Until here everything looks fine.
But I notice that the valve don’t lights, and is just a very little hot.
Tension in C9/c17styro/R14 is about 71 V
In the tension divider R12/R13 I read 55v
In R10/R11/R12/R9 I´ve measured -1.7V
In R8/R9 -2,9v
In R8 with turret Pin 9, -0.8v
Before R2 55v and after, to the turret /Backplane I READ ONLY 8volts!!!
This measuring are the same with the capsule and without.

I measured the capsule, one beeznez K67 is about 56pFx 2
The first time that I populate, I was think something is wrong So I cleaned the PCB´s and measured all the components, including the transformer (ami t-67 BTW) Everything reads OK.I populate a second time, the measurements are exactly the same. I was go a house of a friend, We clean again and populate with news components, and the reads still the same.
I´m a little desperate, I use to repair a lot of things during years, We have refurbished an Old Api 2488, so I think I know something. also two years ago I was built  a Sound Skulptor Mp-66 valves micpreamp and no was difficult for me. Anybody have any Idea about is happening? 
Thanks in advance!!!

 

[tonitu]

Still hoping for a bit of help here.  I've complete my build and I'm having some issues at calibration.
For a start I measured the PSU, mic  not connected, and I get the following values:

Heater = 22VAC
AC In 210 = 270VAC

B+ = 227 DC
H- = -17.77
-----------

Mic plugged in, no tube:
B+ = 249
H- = -17.66

0.9 Ohm  between the mic body and the chassis of the PSU
---------------

Right after measuring my PSU gave out.  It kept blowing fuses and the last fuse I put in I could smell a bit of electrical burn.
I took out the PCB and could see that D1, the 15 V 5W Zener diode  has burnt out.
What could the reason for this be? 

Cheers,
Dennis

Hi Dennis, I also had the same problem , Even if it does not burn the diode , 22 VAC in the heater line is too high when you dont load the PSU, and the diode can burn. In Spain the line can vary from 205 Volts to 235, this cause a lots of problems in this kind of regulation. Dan told me : Please no more than 20 vac in the heater!!, and it works perfectly. When the line is near 220vac, No problem without load, whem rise a little the temperature in the zener is critical.  Hope this help.

 

[micaddict]

I'm in the process of doing all of the research for this build. I have some issues with reading so... parsing a 59 page thread is a little daunting. I'm wondering if anyone who has recently done this build can help me out? Here's my understanding of what I need:

All 5 items from the PCB-D-67 kit from this page $89:
http://www.vintagemicrophonepcbkit.com/orders.html

This mic body kit from Studio 939 (SYT-5 Gen 3) $145:
http://store.studio939.com/product/syt-5-microphone-body-kit

The components for the microphone from this BOM $45.05:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=83ad963d23

Now, here's the first problem, the Vishay 0.47uF cap is obsolete. None of the equivalent options are in the same package. What is everyone using for that? I've narrowed the field down in the following link. Looks like the Wima and the Nichicon caps are the closest matches but neither are the same form as the Vishay. Will they work in this build? The Wima doesn't even have bendable leads... could solder some leads to it but... still, tight spaces etc. What is everyone else doing?

http://www.mouser.com/Passive-Components/Capacitors/Film-Capacitors/_/N-9x371Zscv7?P=1ywtgmbZ1yznbzsZ1z0wquaZ1yzs9nv&FS=True

The components for the PSU from this BOM ****MINUS THE CASE**** $95.38:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=b5c122b4d0

This case from Collective Cases $65:
http://collectivecases.com/?product=psu-cases

An HK67 Capsule from Heiserman Audio $250:
http://www.heisermanaudio.com/store/p4/Heiserman_HK67_Capsule.html

AMI T67 Transformer from Zen Pro Audio $110:
http://www.zenproaudio.com/tab-funkenwerk-ami-t67-transformer

Amerpex EF86 Tube $99.95:
https://tubedepot.com/products/amperex-ef86-6267

Total cost: $899.37 (plus some shipping charges I'm sure)

Is there anything I'm missing?

I like Philips (including those rebranded as Amperex).
But hey, I'm biased.
Pun intended.  ;D

I've never paid 100 bucks for an EF86, though.
I might for a stellar Telefunken EF806S.
Just might.

BTW with a slight adaption (heater) you could use PF86, too.
Fine tubes and there's less chance you'll get the dregs.
Unless Max has bought them all by now. 

 

[dmp]

Is there any science behind determining which of those would sound the best or does it come down to trying it in the circuit and hearing how it sounds?

Yup, as long as the capacitance is the same, the 'science' is trying to even hear a difference. You can do null tests to isolate what is different if you really want to dig into it.  If you are comparing different types of caps you're more likely to notice something, i.e. film to PIO.  Blind tests are good when doing this sort of thing.
Choosing correct components is a big part of DIY so you're on the right track.