Neumann Vintage U87 Clone : Build Thread.

[poctop]

Thanks for the great guide Dan,this will help a lot,especially the guys who are not-so-experienced.
Running the 4 connection wires on the bottom sides is a great idea,this will keep the top side cleaner.
May I suggest to add something to your considerations list?
That is to tell people to never touch the capsule or parts of it directly with the fingers.This is the very high impedance part and is absolutely non-forgiving.Wearing thin gloves does the trick.

Best,

Udo.

thanks Udo for the kind word just added your suggestions 

D

 

[Blue Jinn]

BTW, FYI, Marik has a 10:1 transformer, there is a white market listing for his transformers.

 

[poctop]

My guess is the real one is #1

Do I hear some slight distortion on 2 and 3?

Eeeehhhmmmmm....."slight" distortion on #3?

I will have to find out if an ExtraPush in drain will give me some better result tHd wise ,  i was under the impression that when i'd used the tHD indicator i had a bit higher final Drain voltage i will report my findings and more result    i should maybe consider testing with a pop filter too

 

[kante1603]

My guess is the real one is #1

Do I hear some slight distortion on 2 and 3?

Eeeehhhmmmmm....."slight" distortion on #3?

I will have to find out if an ExtraPush in drain will give me some better result tHd wise ,  i was under the impression that when i'd used the tHD indicator i had a bit higher final Drain voltage i will report my findings and more result    i should maybe consider testing with a pop filter too

You're using a large diaphragm mic and being close while talking to it without pop filter?
That's "brave" ( and a capsule killer:moisture is the enemy #1,followed by dust).

Udo.

 

[Ayman59]

Guys,
Long life to this forum!!!
I have a question for U???

About my B2 Pro mic that does not have the
metal tube casing at the bottom of it. The one that separates
the circuitry from the xfmr.

Is the xfmr supposed to have a metal shield over it?
or anybody put the xfmr into it without this protection?

Thank u for u're advices!!!
Jérôme

 

[kante1603]

Guys,
Long life to this forum!!!
I have a question for U???

About my B2 Pro mic that does not have the
metal tube casing at the bottom of it. The one that separates
the circuitry from the xfmr.

Is the xfmr supposed to have a metal shield over it?
or anybody put the xfmr into it without this protection?

Thank u for u're advices!!!
Jérôme

Hi and welcome,

funny I worked on that exactly today for my B2pro builds-no joke!
For non-b2 builders:this mic is transformerless but has a little space for it at the bottom.
I decided to cut some metall tube from an old damaged chair off,say arround 35mm,approx. 25mm diameter.I will glue it to the bottom and leave it open on top to run the wires.The T13 trafo should fit in there and will be held by rubber foam.That's what I'm going to do.
Having metall as shield won't hurt I think since the trafo has no can,but I think it is not necessary.
Anyway,be carefull that you don't short out the xlr connectors,I used shrink tube at this point.

Hope to have helped,

Udo.

 

[saxmonster]

Why are we using r6 now?  Does this mean that I have to re-bias?

thanks
-Scott

 

[poctop]

Why are we using r6 now?  Does this mean that I have to re-bias?

thanks
-Scott

Did you bias with the scope ?  the R6-C4 point is the injection point for the signal to calibrate as the Matador method ,  there is other way using the RT and SW pad but i dont want to create confusion , so we will stick to Matador Method Now.
Sorry for the confusion.
Dan,

 

[saxmonster]

Yea i use the rt and sw pads with a scope on my computer and picked the clear middle point between when the distortion points starts at both ends of the screwing in the pot and unscrewing it.

-Scott

 

[kante1603]

Scott,

That's o.k.,c4 is just another injection point,it's the point matador suggested for the scope method.
Since somebody else here and me ran into oscillation trouble during measuring via rt using a real scope I gave it a try and it worked out fine for us.
Anyway,I think you're done.

Best,

Udo.

 

[poctop]

I just Added in the BOM  Udo Suggestion ( thanks Udo)  using molex header for the Traffo connection pad LC, capsule connection and all pad connection it make it easier just have to cut the pin a bit , it makes it cleaner also and more tolerant for resoldering if any  ;D

 

[wave]

RK-87 arrived today



Now I need my donor mics!

Dave

 

[poctop]

Wow that Was Quick so it seems you are officialy the First Beta Tester , wich traffo will compliment this one ?

 

[wave]

Wow that Was Quick so it seems you are officialy the First Beta Tester , wich traffo will compliment this one ?

Dan,
I am going to test this capsule in 2 flavors.

1. All styrenes and the AMI T-13
2. Mica, Films and electros and the Cinemag 2480

You actually might get to the testing first as I'm still waiting for the donor mics.

Dave

 

[marshman]

Quick question regarding the idss...

when measuring this, is there an optimum value to look for? Highest? Lowest?

Thanks,

mm

 

[berkleystudios]

Just got my capsule today!!!

i will be doing mine with the cm2480 flavor. once cinemag ships it of course....

 

[poctop]

Quick question regarding the idss...

when measuring this, is there an optimum value to look for? Highest? Lowest?

Thanks,

mm

Lower is Better, if you can find between 8-12 you will be in the nominal range and you will be fine, 
Dan,

 

[kante1603]

Wow that Was Quick so it seems you are officialy the First Beta Tester , wich traffo will compliment this one ?

Dan,
I am going to test this capsule in 2 flavors.

1. All styrenes and the AMI T-13
2. Mica, Films and electros and the Cinemag 2480

You actually might get to the testing first as I'm still waiting for the donor mics.

Dave

Wow Dave,that´s cool.
I´m really interested in how the old or vintage version compares to the budget but modern style flavor wise.
Will you build 2 microphones at the same time or one after the other-having both at the same time is better to compare since one can test record from the same source.

Cheers,

Udo.

 

[kante1603]

Quick question regarding the idss...

when measuring this, is there an optimum value to look for? Highest? Lowest?

Thanks,

mm

Hi,

look for lowest.
The Fairchild spec sheet says the lowest IDSS is 2mAs,the max. is at 20mAs.
Have tested a couple of them,arround 40 pieces.
Most where in the range of 10 to 12mAs,none exceeded 14mAs.
I have one with 8,7mAs in my build,and the best I found is at 5,9mAs.
So I think it´s worth to shoot out a bunch of them.They´re cheap and easy to source.Here in germany they are at 15 Euro cents for a single,price will decrease a bit when bought in hundrets or so.
For this I have made a small veroboard for easily testing them.
The pics:

A nice little helper that cost nearly nothing and takes just 5 minutes to solder.

Best,

Udo.

 

[adeptusmajor]

a couple of pictures:

and a link to a thread I made just for the gearslutz, with a few more explicit pictures  ;D

http://www.gearslutz.com/board/so-much-gear-so-little-time/724466-check-out-pair-u87s-i-built.html