Neumann Vintage U87 Clone : Build Thread.

[HellfireStudios]

OK,  I've checked out my two Peluso capsules and they are the same, but different from the above description.

The side with the lead on the rim's face is connected to the brass rim of the other side.  The two brass rims are indeed isolated. Attaching the fourth lead as described above only duplicated the function of the existing lead.

So, does anyone know for sure if attaching to the other (opposite) rim connects to the other backplate?  And is the capsule really asymmetrical?  If so, which side is the front in light of the above?

I guess I'll try Peluso on monday if no one knows... 

If you don't attach both backplates to the PCB you will only get a cardoid polar response. Both backplates are integral to the pattern selection.

The front capsule is the one with both leads attached already.

FWIW, when I got my Peluso K87i capsule, it came with a tiny brass screw-down terminal. It also came with three screws (two for the mount, one for the additional backplate).
Attach a wire to the terminal. Attach the terminal to the side of the capsule (look at the capsule that came with the mic), not on the rim like the front backplate. You can use any of the holes in the back backplate, after you've mounted the capsule. Just poke a hole in the tape and use the remaining screw for the terminal. I hope this is clear enough.

 

[poctop]

I had posted this in the thread on page 3

in this case with the peluso capsule as the original K87  the 2 backplate front and back are isolated electrically this is guaranteed,

The Answer is the front backplate tab already on the capsule is for the front capsule so this is how you recognize the front , there actually on opposite side because of that 
the (back) backplate will connect via a tab that you need to supply ( Peluso Wisher will be providede one) and attached to the mounting saddle connection so it will make contact will the back backplate only,

So the connection on the PCB are for FC = front capsule  (cap = capsule and bdy = backplate) and same for the back diaphragme  as the RC section on the PCB Cap= back capsule and bdy back backplate,

Hope this helps,
Dan,

 

[wave]

How much difference is there to the circuit if a 68Mohm is used in place of the 60Mohm?
Also, has anyone source the 10pf styrene from justradios? It's rated at 630V. Is it physically large? Could all the styrenes be that voltage rating (from a size perpective)?

Thanks
Dave

 

[wtmnmf]

I had posted this in the thread on page 3

OK, I see that now

I have the picture labled with 2 as the front and 1 as the rear, but I don't think that there is any difference because the capsule does omni and figure eight, so the front and rear should be the same.  Right?

**************

Ignore spelling error below  :-[

Diaphragm not diaphram, diaphragm not diaphram  :

 

[poctop]

I had posted this in the thread on page 3

OK, I see that now

I have the picture labled with 2 as the front and 1 as the rear, but I don't think that there is any difference because the capsule does omni and figure eight, so the front and rear should be the same.  Right?

In Theory they are the same but pratically it is always the one with better (if it is the case
) frequency response that is selected as the front because in the omni or 8 the back side is less sollicited, the capacitance is also optimize for best output with the front,  but without all the measuring apparatus we always reference the front with the one side that has the tab in place and that is on the other side of the capsule,  just an old rule i was always told.

By The Way thanks For The Picture i think it will help  others as well,
Dan,
 

 

[saxmonster]

Ok I am totally confused!!!! for the front I used the Side with both the membrane attach screw and a screw / tab that was attached to the front rim screw at the 6 o'clock position.  Do these two get attached the front section solder points on the pcb?  Or is the one that was already attached to the rim from the factory part of the rear section.  You would think John would have this on his site somewhere. Just frustrated now, sorry.  I thought I was done errrr.

 

[wtmnmf]

In Theory they are the same but pratically it is always the one with better (if it is the case
) frequency response that is selected as the front because in the omni or 8 the back side is less sollicited, the capacitance is also optimize for best output with the front,  but without all the measuring apparatus we always reference the front with the one side that has the tab in place and that is on the other side of the capsule,  just an old rule i was always told.

By The Way thanks For The Picture i think it will help  others as well,
Dan,

That's interesting.

A few tips for those using Aurycle bodies...  the saddle has two levels along the parting line, which doesn't matter if you are using screws on one side, but the way mine lined up I needed to drill one of the holes on the other side which resulted in the capsule leaning a little.  I wrapped a piece if sandpaper around a small bottle of the right diameter for the new capsule and sanded it both smooth and to the correct size.

My second body appears to have seen high enough G-forces to have ripped the saddle post 99% of the way off of the base!  The capsule was leaning over 45 deg. when I took the headbasket off.  I thought that cyanoacrylate would probably not work, but I gave it a try anyway, and it worked very well    Maybe someone else will have a similar problem (what do you want for nearly free?).  I bought the assembled ones with shockmount and case.

The Peluso supplied screws are too long to attach the tab for the backplate connection, but they are fairly soft, and snapped off OK when I used the way-too-big screw cutter on my ring terminal pliers.  Loosing half of the length worked fine when fitted with a washer and the terminal.

Another issue that may be confusing, with regard to the capsules - if you're poking about with an ohm meter, is that some of the screws on the faces are insulated from the brass on that side (like the one for the front backplate), and some are threaded into the nearside.  I'm guessing that the construction is like a real U87 capsule where you can see three screws of a different type on each side that secure the two halves together without shorting them, except Peluso use the same screws type all around.  I saw a post on the Neumann site where someone tried to repair a broken off backplate tab by mounting it to the adjacent screw.  That was a non-functional solution.

BTW, the stock Aurycle capsules in my mic's had scrap in the holes under the diaphragm and sandwiched between the diaphragm and the brass (what is that part called?), as well as wrinkles in the diaphragm.  Those can't be good defects.

 

[poctop]

This is the Correct Way to make sure you have the front is the Front an the Back is the Back ;D

I have corrected your picture so everyone can take a peak at it  the connection for the front Backplate is actually on the other side the reason for that is that it uses insulated screws this are exactely like the vintage K87 capsule . the external tab mounted on the face of the diaphragme is always the Front Backplate connection i know this may be confusing but this is the way it is.

this is the correct connection to do and are labeled,

Capsule connection side A

 

[poctop]

Capsule Connection Side B,

 

[saxmonster]

Thanks Dan,

I am going to rewire it right now.  Do you think I will notice a difference in sound, hahahahah.  I can't believe I did it wrong.  Oh well thanks for correcting it.  Hopefully this will help others.  John should send directions with these, pictures are better then emails hahahaha.

Thanks again
-Scott

 

[poctop]

Thanks Dan,

I am going to rewire it right now.  Do you think I will notice a difference in sound, hahahahah.  I can't believe I did it wrong.  Oh well thanks for correcting it.  Hopefully this will help others.  John should send directions with these, pictures are better then emails hahahaha.

Thanks again
-Scott

No Problem :

just adding to this that normally the Back Backplate connection is made trough the saddle if possible that make it easier to deal with.
A big tip is also to cover the capsule if you use a soldering iron do to anything nearby because you want to make sure that no flux end up in the diaphragme so be carfull and aware of this

 

[wave]

Could anyone comment on the possible audio differences between using tantalum or electros for the 22µF and the 4.7µF caps?

Thanks,
Dave

 

[saxmonster]

I don't have that much experience with different components as this was my first microphone build Wave, so I just put everything that the original had in it. 

I just did the rewire and the mic sounds even better with the voice check 123.  Will run some sax through it tomorrow.

-Scott

 

[kpearsall]

ok guys, what are the considerations and process for building a "matched" pair. Do I just need to match the fets? how would I do this? Peluso doesn't seem to advertise matched capsules. At least, I didn't see it!

 

[adeptusmajor]

Thank you Scott and Dan for the pictures. Very helpful, I guess I was about to do it wrong.

 

[adeptusmajor]

Could anyone comment on the possible audio differences between using tantalum or electros for the 22µF and the 4.7µF caps?

Thanks,
Dave

If you check the first page of the white market thread, Dan built two mics with different components and gave a brief description of the differences in sound.

 

[pavthefiddler]

This is the Correct Way to make sure you have the front is the Front an the Back is the Back ;D

I have corrected your picture so everyone can take a peak at it  the connection for the front Backplate is actually on the other side the reason for that is that it uses insulated screws this are exactely like the vintage K87 capsule . the external tab mounted on the face of the diaphragme is always the Front Backplate connection i know this may be confusing but this is the way it is.

this is the correct connection to do and are labeled,

Capsule connection side A

Thanks Dan for explaining this! I just wired my Peluso capsule and I would have done it wrong without it.

I'm almost done with the microphone, just waiting for a few more components from justradios.com and the cinemag tranny.

I'm using a B2 Pro body. I was lucky to have one without the engravings so I just painted it with green Hammerite (hammered finish), making sure I didn't paint over the both ends (to maintain the electrical contact with the rest of the mic).

I have 3 questions:

1. The boards don't quite fit the B2 Pro body (using the existing mount points). Has anyone come up with a tidy way to secure them and connect the PCB ground to the mic body?

2. B2 Pro body has the all 3 switches. They are mounted on a little board that keeps them in place. I just removed all the other components from the existing board, cut all the traces leading to the switches and I'm going to solder the leads directly to the switches and then to the 2nd PCB. Is that the correct way of doing it? Does anyone have any experience with B2 Pro body? Is it going to be beneficial to the sound/RF noise pickup/etc if I don't wire the switches and use just the jumpers on the PCB? I'll switching between the patterns quite regularly (that is if the mic works!).

3. How do I wire the pattern selection switch? I can't quite work out which pins on the PCB need to be connected to result in a particular pattern.

Thanks a lot!

 

[pavthefiddler]

Different angle

 

[kante1603]

3. How do I wire the pattern selection switch? I can't quite work out which pins on the PCB need to be connected to result in a particular pattern.

Hi,see my reply #189 just one page back!

Udo.

 

[pavthefiddler]

3. How do I wire the pattern selection switch? I can't quite work out which pins on the PCB need to be connected to result in a particular pattern.

Hi,see my reply #189 just one page back!

Udo.

Thanks a lot! I never noticed the attachment.