U47-style bodies - who can make one?

[synthi]

I was pretty sure is brass.. but its steel!?

 

[Skylar]

Hmmmmm.

Well if the "chrome" plating is actually nickel plating, that could make it magnetic.
The question would be "Are the top and bottom headbasket rings magnetic as well?"


Because you can't solder steel without high temperatures (think acetylene torch), silver solder, and special flux,
I tend to believe that Neumann used brass wire cloth for cost and ease-of-assembly.

I'm betting what we saw on the U87 video is not far from how it was done in the 50s.
Though they didn't have solder paste back then, so probably a bit more manual labor.

 

[e.oelberg]

the plating is nickel at a original u47

 

[mad.ax]

From this picture the 3rd layer of mesh is obviously smaller than the 1st one. On the screen if I measure the lenght of 6 cases of the first layers, I get the same lenght than 7 case of the 3rd one.

Axel

 

[craptical]

The rings are not magnetic. The mesh however is "very" magnetic and together with the pictures from FLEA, I draw the conclusion that the mesh is indeed steel/iron. I´m not a soldering expert, but judging from the look of the inside I strongly believe it´s an open flame type of job.

/Dave

 

[Skylar]

Axel,

I agree, the inner mesh looks smaller than the outer mesh.
When I measured it onscreen (and you can easily see this), there was a lot of variance from grid to grid on the inner mesh.
So, I wasn't sure...thank you for confirming my thoughts.

It's looking like the inner mesh is 10x10, 0.020" wire diameter; whereas, the outer mesh is 9x9, 0.023".


Dave, yes, that info now suggests the mesh is steel.

 

[mad.ax]

A solution to get the last word about the mesh should be to ask Gleier Galvanik. Since they did the job for Neumann, they must know if the grill was made from brass or steel.

The solid brass ring (especially the big lower one) will need much more heat than the brass mesh, and there would be a risk of deformation from said mesh...
I wonder if the higher temp necessitated to solder the steel mesh wouldn't match the temp for the brass ring...

There could be a third route to explore: stainless steel and conductive epoxy.... The mesh can be found in stainless steel, the ring can be machined from the same material. We could even machine the whole headbasket from a stainless steel 63mm tube, and glue the grill inside it with conductive epoxy. This would mean no soldering, and no finish fee....
The only tooling needed would be the cast to shape the dome (a bit harder to bend with stainless steel than with brass) and ideally to get the grill spot welded.

Axel

 

[Skylar]

Well, if we're going to change the materials, why not just use brass mesh?!

 

[Skylar]

Really, will using brass mesh (as opposed to steel) alter the sound?
I doubt it!

 

[mad.ax]

I see some kind of ring inside the grill in this pic, and I wonder if it's the upper ring, or some wire used to solder the dome shapped grill with the circular one.... In this case that would mean that the whole grill was assembled first, and the upper ing is only here to hide the solder joint....

I made some red line on the pic to show the ring I'm talking of...
Axel

 

[e.oelberg]

if you really want to know I could walk to gleier galvanik and ask them, my studio is just beside gleier.

nicholas

 

[mad.ax]

Skylar,

if we use brass or regular steel mesh, we'll need to have some kind of finish applied in order to protect the mesh from oxydation.
That wouldn't be the case with stainless steel....

Nicholas,
thanks for your offer, that would be perfect!

Axel

 

[Skylar]

Axel,
That looks like the ridge that's machined into the upper ring to me.

I think the cost of machining from stainless would FAR outweigh any finishing costs.
Machinists don't like steel--most don't have the equipment to do it with anyway.
There is a reason that tooling and dies are so expensive ($thousands)...because they are typically machined from steel.
Machining stainless takes about 50% more power than machining mild steel which takes more power still than machining aluminum/brass.
The cutting tools must also be constantly cooled & lubricated and resharpened at regular intervals during fabrication.
A lot of care must also be placed in securing the part to prevent breaking the part/cutting tool due to vibration & chattering.
All of these extra requirements add up to extra $$$.


nicholas,
It would be great to know what the original used! Also, maybe they know HOW the grilles were constructed. ?
AND it would be AWESOME to know exactly what finish techniques were applied on the shiny and matte headbaskets as well as the bodies!

Are the shiny headbaskets chrome or nickel-plated?
EDIT: okay they're nickel per your previous post.

Are the shiny headbaskets polished, plated, then polished again or some other technique?
Are the matte headbaskets bead-blasted then nickel plated or some other technique?
Are the aluminum parts anodized or plated? If plated, what technique was used?
¡MUCHAS GRACIAS!



My guess is that the earlier grilles were steel, and they switched to brass at the same time that they started matte-finishing them.

Think about it...Dave says the matte grilles are not magnetic...gotta be brass.
If the matte grilles are brass, then there should be no issue with using brass for our grilles.

 

[mad.ax]

Skylar,

what makes me doubt about the ridge is illustrated on the pic below... The wire from the dome shaped top seems to goes behind the ridge!

You are certainly right about the machinning cost of stainless steel... For the rings or tube they would be prohibitives!
But to finish with the cheap and different route, what about stainless steel grill, aluminium tube, and conductive epoxy?

I too would prefer an all brass solution, with a nice&shinny nickel platting finish... But I'm affraid of soldering and plating costs...

I don't think that the grill material is an issue soundwise, the 3 layers sandwich and all the soldering forbids any resonance...

Axel

 

[Martin B. Kantola]

Stainless steel is not magnetic...

Martin

 

[matta]

Firstly guys, I REALLY want to commend ALL of you on your hard work, the attention to detail here is nothing short of astounding and I thank you all!

I really hope we can pull this off as I'd love to get a body for my Mk7 mic I plan to build.

I read ALL these pages last night to get ahead of the pack and make sure I didn't miss anything.... one thing I did noticed is that right now we still don't seem to have the measurements of WHERE the capsule sits within the head cage (unless i missed it)?

I notice that 3 different members are selling M7 capsules mounts with rubber standoffs, the problem I foresee is that if one buys them the standoff height will put the capsule further or close to the base of the headcage grill, how do we know the standoff height? Is this standard between mics?

Craptical, or others who are blessed enough to have access to a REAL U47 could you measure the mount height/diameter? I think this info will prove value to those selling mounts in the Black market so we can try and source the CORRECT mounts to place the capsule at the correct height in the headcage.

I did spot your pics and measurement but they seem to show form plexi mount to ce3nter of the capsule itself, also do we think we need to have the plexi mount as well? Also seem that the pattern selection will be remote since there isn't an allowance for a switch? I assume this is correct?

Again, I can't thank you all enough for your hard work, this really does look amazing! Viva la DIY!

Cheers

Matt

 

[Skylar]

Technically, there are grades of stainless that are magnetic, though maybe not as common as non-magnetic stainless (which has nickel added to strengthen its oxide layer).

Think about stainless knives that stick to magnet holders.

Regardless, we were just talking about using stainless as an option, not proposing the originals used stainless.


Axel,

I like the option of stainless and conductive epoxy.
Are you saying aluminum with a high polish for the headbasket rings in lieu of plating?

I still think that, overall, my favorite option is an all-brass headbasket/mesh combo.

I suppose we could just offer the parts to assemble the headbasket and let people pick out their own mesh?
That's an option I guess.

 

[Skylar]

matta,

If I recall correctly, craptical provided the important measurement of capsule center to base, which will tell us how high the capsule mount will be.

The trouble is, with so many different mounts floating around, it's really up to the user to shim up (or shave down!) their capsule mount to meet this measurement.

After sorting through the pages, I have found the measurement:
40mm from plexi to capsule center.
the plexi is 5mm thick.

So, as long as your capsule center sits 45mm from the capsule mounting disc, you've met the original spec.

 

[FerrariT]

I think it should simply be thought thru as to which mesh will effect the sound / acoustics and by how much good or bad?

It may be found that the brass has a better sound.

Or aluminium even.

certainly, your not going to spite the quality of the sound just to have an 100% repro body?

Now if steel has the better sound then excuse me.

I'm at a lost as to how much said metal wwell sound versues each other.

I do know that this is coing along beautifully

any word from machinists? any guesstimations at this point on $$$

 

[Skylar]

I honestly don't think that the mesh material will have any effect on the sound.
What it will affect is price / ease of construction / finish options.

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