Neumann Vintage U87 Clone : Build Thread.

[poctop]

Hey Dani and everyone. Built this couple of years ago, and had intermittent problems with low "motor boating" kind of sound with occasional pops…happens all the time now…thoughts?

Thank you.

Did you upgrade you polystyrene caps for the HV ones, 630V,  it fixed problems like this one in the past,
the update has been made a long time ago on the post somewhere.
Best,
dAn,

 

[geekmacdaddy]

I'm pretty sure I started with HV's except maybe one that I couldn't find, but…I will try replacing all Polystyrenes….Thanks Dani 

 

[poctop]

I'm pretty sure I started with HV's except maybe one that I couldn't find, but…I will try replacing all Polystyrenes….Thanks Dani 

if it does not work, the I would suggest the breath test on capsule and capsule examination to see if it is proper no wrinkle of anything of some sort,
Best,
Dan,

 

[geekmacdaddy]

Just checked, they were low voltage. Forgive, I will read the thread in reverse looking, but does anyone have a source for the HV Polystyrenes?

Thanks in advance
Geek

 

[melomane]

Hey, i want to add some led to the U87 project (power indicator). my question is, where do I power this light on the pcb?
light specification: 3V (20mA). Can you also tell me the resistor value to add? thanks

 

[kante1603]

Hey, i want to add some led to the U87 project (power indicator). my question is, where do I power this light on the pcb?
light specification: 3V (20mA). Can you also tell me the resistor value to add? thanks

Hello,

the led you specify is no good idea.
An original  U87 is supplied by 48vdc +/-4 at 0,4mAs.
Your led is 50 times higher in current consumption.
Given you still want to use this led a pre resistor tapped off the phantom power (e.g. at the xlr) will be around 2k7.
The wattage burnt will be ca. 750 mW.
This will turn your microphone into an electric heater including lightshow.
And you'll have to use a big resistor,e.g. a 1 Watt type.
No good idea........
So you might want to go for a low current type.

Best,

Udo.

 

[melomane]

Hey, i want to add some led to the U87 project (power indicator). my question is, where do I power this light on the pcb?
light specification: 3V (20mA). Can you also tell me the resistor value to add? thanks

Hello,

the led you specify is no good idea.
An original  U87 is supplied by 48vdc +/-4 at 0,4mAs.
Your led is 50 times higher in current consumption.
Given you still want to use this led a pre resistor tapped off the phantom power (e.g. at the xlr) will be around 2k7.
The wattage burnt will be ca. 750 mW.
This will turn your microphone into an electric heater including lightshow.
And you'll have to use a big resistor,e.g. a 1 Watt type.
No good idea........
So you might want to go for a low current type.

Best,

Udo.

thanks Udo for your quick response. I understand... but I don't know if it's possible to find led with low current... the +48V from phantom power supplied what current generally?

 

[kante1603]

thanks Udo for your quick response. I understand... but I don't know if it's possible to find led with low current... the +48V from phantom power supplied what current generally?

Do a search for "low current led" in your country,I'm sure you'll find a lot of info,I even bet your local supplier has some stock.No exotic parts these days...you can find them everywhere.
Most start at ca. 2 mAs,depends on colour,size etc.

There's no general current supply for phantom power.It depends on how much current is taken by the microphone,the active d.i. box or whatever you connect,and how much current can be delivered by your psu.

For the led preresistor,there are many calculators to find in the internet.......or use Ohm's law.

Best,

Udo.

 

[0dbfs]

Don't the 6k8 parallel resistors in a phantom circuit limit the current to 7ma each for a total of 14ma?
I believe the IEC specifies 10ma. as a max value.

Cheers,
jb

 

[kante1603]

Don't the 6k8 parallel resistors in a phantom circuit limit the current to 7ma each for a total of 14ma?
I believe the IEC specifies 10ma. as a max value.

Cheers,
jb

Hi jb,

generally you're right,although from what I know the 6k8s are more meant as decoupling resistors preventing the signal from being shortened.
Also different specs can be found for these resistors (e.g. 6k8s for 48v but 680r for 12v etc.) which alters the max. current.Sure,I'm used to calculate with the mentioned 10mAs per line too.

But still the current of a standard led is ridiculous high compared to the consumption of the microphone itself.
That's what I was after,and that's why I recommended a low current type to use.
To keep the "sound-to-lightshow"-ratio a bit more "acceptable",hahaha...... ;D

Thanks for sharing,have a nice weekend,

Udo

 

[0dbfs]

Yes. I don't know about the LED idea but some mic's have an externally powered LED indicator (brought out to two pins on a 5 pin XLR) for use in broadcast to be used as an indicator when that mic is live on-air. That can be useful in those situations and it's generally externally powered / switched ON/OFF in those cases. I have seen some rode mic's with an LED that can be configured like that but also can be configured to be switched on (internally powered via 48V) when HPF on the mic is active or as a 48V present indicator. It's certainly not super-bright. Would be interesting to trace that out and see how they manage the current in those situations.

Cheers,
jb

 

[kante1603]

A lot of modern mics have some status indicators built-in these days,e.g. modern AKG C414s for pattern selection.These are very small,not bright (as you already stated) and I guess ultra-low current.Easily doable at a max. current of 10mAs.
I know there are types working in the mikro-Ampere range.
Also I think it depends on what one will achiveo I need a lightshow or just a visible indicator?
If it's for indication I'd start with a low current type,roughly calculate the needed current limiting resistor from its' specs and then increase the value until I find the brightnes suitable.

Cheers,time to sleep now,

Udo.

 

[heeters]

Hey guys I have a bit of a problem. I accidentally soldered a resistor in a spot where a different resistor was supposed to be. So I heated up the solder joints and managed to pull the resistor out. Then I saw that the through holes were filled with hardened solder and I couldn't push the leads of the correct resistor through. I'm new to this and I didn't have access to the internet at the time to research this issue. So I'm kind of an ***** for doing this.  I stuck the pointy tip of my soldering iron into the hole and melted the solder inside and tried to scoop it out I guess. This took a while so the heat may have really messed up the hole. On the top of the pcb you couldn't really distinguish the metal eyelet that goes around the through hole anymore, I don't know if it fell off or what.

So with this specific pcb board, what kind of damage could I have done to it? I dont have the board by me right now so I can't really get any other ideas. Is the inside of the hole shielded with metal all around? Maybe I just messed up the conductivity by coating the inside of the hole with cold solder and flux?

 

[Rocinante]

You NEED to get some kind of desolder sucker. Be it the turkey baster kind or quick pull or a haiko desolder iron. You can get the pump kind on Ebay for real cheap. You need to suck what you can of the solder out of there. I remember some thread where Jeff from CAPI was explaining to someone also new to Diy in a similar situation but with a gar 2520 (which are far harder to solder or repair since the components are so close together) that its rare for all to be lost and with some serious cleaning up after desoldering the pcb should be still usable. There are some useful sites online for such instances. Search some more but with the knowledge that many have been there before (including myself) and have done nearly the same thing. More than likely it will be fine.

 

[kante1603]

@heeters


Hello and welcome.


From what I remember the pcbs are single-sided,so when an eyelet came off on the top (no traces) side it's an easy fix.


Two steps:
First get the holes clean and opened up.
If you don't have a hightech machine like the Hakko do it with simple solder wick.
The trick is to apply (!) some fresh solder to the points,then lay the solder wick over the solder point a gently press it down with the iron tip,hold the tip a bit angeled,not perpendicular.You will see the solder flow into the wick sideways.You might want to practice it on an old piece of veroboard or another pcb when you haven't done this before.If the area is too ugly now clean it with some isopropylene alcohol.If you have styrenes on the board be careful they don't get in touch with the alcohol,they absolutely don't like it!


Second put the resistor in and solder from bottom (traces side) as usual.
Don't apply too much solder,always keep it at a minimum so that the solder just properly flows.
Check if both resistor sides have continuity to their next connecting parts after the schematics.If they don't you must replace the corresponding trace(s) with a small piece of wire or cut-off resistor leg(s).
Done.


If still unsure you might want to post a pic of it from both sides.


Best regards,


Udo.

 

[heeters]

Excellent. Thanks a lot for the info, guys. 
Well I'll get some solder wick or a solder sucker and then test the continuity after i get the new resistor back in.
Also i'm glad I know now about the styrenes and the alcohol. I was cleaning with alcohol and I know I got a tiny bit on them. I didn't notice anything out of the ordinary though.

 

[kante1603]

O.K.,just keep them in mind in case any issues occur later.



Udo.

 

[Rocinante]

oh boy so I am hoping yu all can offer a little guidance on this.  I am using a B**inger B2-Pro for my build.  Naturally I bought it specifically for this project so I could have switches.  I have hit somewhat of a roadblock which I hope you gents might have a solution.  Unfortunately the switches in the B2- pro I am using  is not like the one Udo had made a tutorial for.  Even if I wanted to just get rid of the factory switchboard the switch pcb Poctop has made won't fit inside the mic.  sigh...  But it doesn't look hopeless.

What I need is maybe some verification on which lead is which coming out of the switches and where I can tie them.  I imaginer i should probably lose that green wima??  Should I just run separate wires from each switch and the capsule to the pcb?

I marked which switch is which.

And this where it comes out the bottom through those pins.  Notice each in sets of two.

And this is where they finally end up and connect to the stock pcb.  I am pretty sure tracing I could figure out which wire leads to where but as of right now I am not positive.  I don't know what those grey wires are for exactly either. 

Is there any chance I can just use the wires coming out of that final point?  Should I run wires off of the switch pins in the second pic to their designated points on the pcb?  Anyone have this version of the b2 that could offer up what they did?  Thanks.  Oh and its a cool project. Thanks Poctop.

 

[Nyquist]

You NEED to get some kind of desolder sucker. Be it the turkey baster kind or quick pull or a haiko desolder iron. You can get the pump kind on Ebay for real cheap. You need to suck what you can of the solder out of there. I remember some thread where Jeff from CAPI was explaining to someone also new to Diy in a similar situation but with a gar 2520 (which are far harder to solder or repair since the components are so close together) that its rare for all to be lost and with some serious cleaning up after desoldering the pcb should be still usable. There are some useful sites online for such instances. Search some more but with the knowledge that many have been there before (including myself) and have done nearly the same thing. More than likely it will be fine.

Another method I used to use before I bought my desoldering gun was to heat the other side of hole with the tip on your iron until the solder melts and then quickly remove it and the the hole a very hard short blow with your mouth. This will clear the leg hole in no time. Takes one or two goes, but no more burn tracks and holes.

 

[wave]

oh boy so I am hoping yu all can offer a little guidance on this.  I am using a B**inger B2-Pro for my build.  Naturally I bought it specifically for this project so I could have switches.  I have hit somewhat of a roadblock which I hope you gents might have a solution.  Unfortunately the switches in the B2- pro I am using  is not like the one Udo had made a tutorial for.  Even if I wanted to just get rid of the factory switchboard the switch pcb Poctop has made won't fit inside the mic.  sigh...  But it doesn't look hopeless.

What I need is maybe some verification on which lead is which coming out of the switches and where I can tie them.  I imaginer i should probably lose that green wima??  Should I just run separate wires from each switch and the capsule to the pcb?

I marked which switch is which.

And this where it comes out the bottom through those pins.  Notice each in sets of two.

And this is where they finally end up and connect to the stock pcb.  I am pretty sure tracing I could figure out which wire leads to where but as of right now I am not positive.  I don't know what those grey wires are for exactly either. 

Is there any chance I can just use the wires coming out of that final point?  Should I run wires off of the switch pins in the second pic to their designated points on the pcb?  Anyone have this version of the b2 that could offer up what they did?  Thanks.  Oh and its a cool project. Thanks Poctop.

I built one like this for someone. I removed all the wires from the switch pcb as well as made sure there were no tracks that were connected to something else...basically just used the pcb for mechanical and convenient tracks.
I soldered the switch wires to the switch legs on the top side of the pcb and to necessary tracks if available.
Then I routed the wires through extra holes I drilled in the black chassis.
The only connections I used the pins in the chassis for were the capsule connections...so capsule to pins then soldered wires from the female pin slots to the pcb.

Dave