Neumann M50

[xmvlk]

Mr. Roentgen,
give me that endowment,
to see
under skin of
women.

 

[xmvlk]

I don´t understand, where the capsule is vented
(vented, because of invention of Wente)
Imho, holes look like too deep - roentgen of real M50 would say truth.
Deep holes = lower compliance of air = lower high resonance.
high resonance = 1/(2*Pi*sqrt(LC))
L ~= mass of the air reduced to the diaphragm surface
C  ~= V of the air in the holes
Damping ~= 1/d^3  displacement of diaphragm

 

[Marik]

roentgen of real M50 would say truth.

I think you want to say X-ray 

Best, M

 

[xmvlk]

I think you want to say X-ray 

Oh yes, in the america you do not honour Roentgen as
inventor of X-ray  ;D

But small industrial betatron do the work on M50 best - safely and undestrictively -
like that:
http://www.ndt.net/article/wcndt2004/pdf/radiography/102_stein.pdf

Best, x(m)vlk

[/quote]

 

[e.oelberg]

Hi,

maybe you could use a Gefell SDC omni for your project. They go pretty cheap on ebay and they might be relative close soundwise.... might be


nicholas

 

[xmvlk]

Gefell SDC

If I understant, Geffels and other measuring microphones are designed
to have best stability
They use Nickel diaphragms etc. , but kk53 or other recording mics was designed
to best sensitivity. It is different trade-off.
Anderson in 1920-ies did comparsion of sensitivities of Al and Fe diaphragms
and  obtain some 1-3 dB gain if use Al instead of Fe (or Ni - near kg/m**3)

I want to have Al microphon of my own construction and I am currently interested to
backplate motive of Al kk53, because I had seen motives of different Neumanns.
And i.e. M55K (kk55?)use grooves instead of holes in backplate design.
It does not imply, that I want to make clone of M50, definitely
not, because I live in year 2008 and today tradeoffs are different.
But I do not believe, that backplate of kk53 is that simple, that is presented on clone.

It was reason why I want to use X-rays to tell the truth.

      Best regards,

        x(m)vlk

 

[riggler]

Hi all, back to DIY again...

Burdij, do you have any plans for the capsule you were working on? I just got access to a precision lathe and CNC machine, and could make these. Even more measurements would be helpful.
THANKS!

And, why not make our own 701 tubes?

http://www.eetimes.eu/consumer/205801104

 

[speakercoil]

So this is my first post to Prodigy-Pro... I have been on gearslutz for a while, but this project caught my eye... I am very interested in trying this out as I am interested in getting into mic building myself...

Random little contribution for you all here. Nothing super technical but it mentions a few aspects of the M50 capsule which I thought was interesting. Also not sure, but maybe wunder sells a replacement capsule for this mic, which would be the perfect contender as it is designed around the original.

http://www.wunderaudio.com/CM4950details.html

Hope this helps somehow.

PS I am about to start a U47 type mic, and I was wondering how Dale's capsule sounds? I had a site that had US or maybe it was Canadian built mic capsule replacement for tube mics, but I lost the link! I am about to resort to a Peluso replacement, but I would LOVE to find something made here in the US or in Canada if anyone knows a good alternative to Peluso.

Thanks, and great job so far!
-Grant

 

[Jim50hertz]

Hi Grant

Welcome to the forum

a comparison of six different m7 capsules including dale's are here, enjoy

http://www.panphonic.com/M7/

 

[speakercoil]

Thanks for the warm welcome!

Here is my background on the M50.

I have done some DIY stuff in the past, but am only now about to attempt my first mic build. I plan on doing this one side by side with my C12 build I am doing.

I got to hear several M50's first hand while interning at Blackbird Studios, including the first one off the assembly line. They are absolutely mind blowing mics... I have heard them hung 30 ft in the air as ambient overheads... Place a-symmetrically as a room drum mic. Overhead spaced pair as drums mics... In a vocal booth for vox... and on an acoustic guitar.

These are such stunning mics, and if we get anywhere close I will be EXTREMELY pleased... I have had way too many wet dreams of owning one of these mics... or even owning a clone of them.

Anyone think of contact neumann for a replacement capsule for the M 150? I know they sell replacement capsules for their current mics... Just a thought. I know it would probably be like 900 bucks from them, but this is all depending on how close we want to get. I mean even a 2-3k build would be half the price of a replica and like.... God only knows how small a percentage of a real one.

-Grant

 

[speakercoil]

Hi Grant

Welcome to the forum

a comparison of six different m7 capsules including dale's are here, enjoy

http://www.panphonic.com/M7/

ooooo... I like Capsule 5 A LOT on that picked acoustic... Such clear lows... mmmmm

Great post, it's nice hearing soloed tracks again of that mic.

-Grant

 

[speakercoil]

Just a thought... What if we based it off of the Blue B4 capsule... Yeah it is a little pricey, but the capsule is based off the M50 mic... Not sure how we would incorporate it into a custom housing, etc... but it's just an idea.

 

[speakercoil]

BUMPITY BUMPAROO!!!!!  8)

 

[speakercoil]

OK!!!!! HUGE UPDATE!

If we can get enough people onboard I discussed this project with the owner of Advanced Audio and he said he could possibly do a custom run of M50 or M150 capsules for us. He said he could do a minimum order of 200 capsules at 50 bucks a pop, OR he is going to see what it would cost for just 50 capsules... Probably in the ball park of 200 a capsule. So I need to see who is interested in this... If we get enough people it is doable. 50 I don't think is too hard to imagine. Especially if I hit up the Gearslutz guys. This with Skylar's body, and the G7 could make for a KILLER mic... Not exactly spot on M50, but pretty damn close for all intensive purposes.

-Grant

 

[rodabod]

If we can get enough people onboard I discussed this project with the owner of Advanced Audio and he said he could possibly do a custom run of M50 or M150 capsules for us.

pretty damn close for all intensive purposes.

It's "intents and purposes"!  Sorry.

 

[bremusound]

OK!!!!! HUGE UPDATE!

If we can get enough people onboard I discussed this project with the owner of Advanced Audio and he said he could possibly do a custom run of M50 or M150 capsules for us. He said he could do a minimum order of 200 capsules at 50 bucks a pop, OR he is going to see what it would cost for just 50 capsules... Probably in the ball park of 200 a capsule. So I need to see who is interested in this... If we get enough people it is doable. 50 I don't think is too hard to imagine. Especially if I hit up the Gearslutz guys. This with Skylar's body, and the G7 could make for a KILLER mic... Not exactly spot on M50, but pretty damn close for all intensive purposes.

-Grant

Maybe i would go for 3 capsules for a Decca Tree array... if the price will be low enough  

 

[speakercoil]

If we can get enough people onboard I discussed this project with the owner of Advanced Audio and he said he could possibly do a custom run of M50 or M150 capsules for us.

pretty damn close for all intensive purposes.

It's "intents and purposes"!  Sorry.

That makes a lot of sense... I am surprised no one has ever corrected me on this over the years... God, maybe my hearing isn't all that great after all. I always said and typed it that way on the assumption of how I heard it growing up. I always though "Intensive Purposes" didn't make sense... I mean aggressive purpose? Yeah, doesn't make much sense. I just figured it was one of those quirky sayings that came from way back when, and maybe intensive at one point meant multiple things. Intents and Purposes makes a hell of a lot more sense.

As for the other comment... 3 is a good start... I plan on 2. So that's 5 to begin with. Maybe I will splurge for 3, but that's pushing it once the cost of bodies, tubes, etc. comes into play.

-Grant

 

[Marik]

OK!!!!! HUGE UPDATE!

If we can get enough people onboard I discussed this project with the owner of Advanced Audio and he said he could possibly do a custom run of M50 or M150 capsules for us.

So would it be an aluminum skinned up to original specs capsule, or just some Chinese jobbie like for example, advertised as BV8 transformer, which has twice as small sized lamination out of poor alloy and unchambered bobbins, i.e. something has nothing even remotely to do with BV8?    

 

[riggler]

Here's what I came up with as far as a schematic for using a Raytheon 5703 tube. Mucho thanks to everyone in the 5784WB thread that helped!

As for the power supply, I found that we can still get the diode tube 150B2. I'm working off an nn48a schematic, which is for variable patterns mics. We'll have to modify it to provide ~5.8-6.0V heater at 200mA.

I compute the original heater load with AC701k as seen by the PSU would have been 40R. I deduce using the 5703 would be 30R.

Here's the schematic for the nn48a PSU:

I'd imagine I'll have to play with R8... could use a hand here...

We've got 25V off of the transformer, rectify it via the bridge rectifier. Smooth with C5, D1 is an inductor? I bit off a little more than I could chew.

Anyway, maybe there's a better version of the PSU for fixed pattern mics. Having trouble getting any schematics on these, lucky to find this one! I asked over at Neumann's forum and will see what that turns up.

 

[PRR]

> As for the power supply

It is not 1958 anymore.

FAR better plans exist to make 120V and 6V without nasty gas-tubes and gigantic resistors.

The 6V is "obviously" 10VAC into a 3-pin regulator, white-bread design.

At <1mA, the 120V is conveniently fixed with Zeners.

If wall-voltage is moderately stable, it isn't even essential to regulate. If both plate and cathode circuits wander the same, the triode will stay at a happy operating point. Since capsule bias is got from "120V", large change will affect capsule sensitivity, but more than 1dB change in capsule sensitivity will reduce incandescent lamp life from months to weeks, and most utilities control better than this.