Neumann M50

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
There is some very good design in the power supply.  Translate and look up one of the parts.
I would keep the basic design and refine it a little with some newer parts.  Don't dismiss the supply learn from it.
In some ways better than a 3 pin.



 
Owning a pair of M50s or at least "almost"-M50s .....!!!! Indescribible! ...would be so amazing....

I've got a couple DIY projects on the go already (and I'm a newb - so it's slow going), but I can't pass up a chance at a pair of capsules, so if that buy is still on, I'd be in for 2 if the price stays below $150US per.

Thanks,
Steve.
 
Sorry I haven't been on in a while, been dealing with other projects. I am sure I can still get the offer made, however I have only had 5 people tell me they are up for it. So unless we get more people interested in buying, it is a long shot. I never asked about the capsule construction in terms of metals being used, but we did briefly discuss it. However he never mentioned it couldn't be done. So I don't have a positive yes or no. The point is that they would be made and designed from scratch, which is why we would need a large order.

-Grant
 
If you look in the drawing board, several gracious forum members helped me to work out a schematic for the mic utilizing the Raytheon 5703WB tube. I have a PSU schematic for an nn48h, but am unsure of the changes to make. If anyone that has the schematic wants to take a gander to confirm / correct my changes to run heater at 6V, 200mA:

Change value of R9. Is it that simple? I don't really see anything else that can't handle the increased current.
The AD130 regulators are still available.
Can use a small toroidal transformer from Amveco for power. Would need about 2.5VA for the heater section (6V * 400mA), and .1VA for A+ (120V * .1mA) . Hope I figured that right.

Unfortunately I can not post the original schematic to the open web per Martin Schneider's request. However, I could share the relevant bits via PM for this project.

 
UPDATE!!!!!!

Ok so why the hell didn't anyone mention you can buy a perfect body replica from flea????????

Sure it's expensive, but it would give the unique characteristics of the head grille that has been discussed in depth on this thread.... hmmmm?

Here's the link...http://shop.flea-microphones.com/index.php?page=productDetail&category=Mechanical+kits+%26+Parts&prNum=55&group=M50

Also there is a capsule which could be obtained here which is pretty similar... about as close as we could get... Though it comes with a useless U47 head, which can be discarded or used as a spare for your U47 (if you are a lucky bastard and own one!)

http://shop.flea-microphones.com/index.php?page=productDetail&category=Microphones&prNum=29

So with those two impossible to obtain items in place (at a great cost)... What's next? The tube and transformer... Which I am doing research on as we speak.

-Grant

 
speakercoil said:
UPDATE!!!!!!

Ok so why the hell didn't anyone mention you can buy a perfect body replica from flea????????

Sure it's expensive, but it would give the unique characteristics of the head grille that has been discussed in depth on this thread.... hmmmm?

Here's the link...http://shop.flea-microphones.com/index.php?page=productDetail&category=Mechanical+kits+%26+Parts&prNum=55&group=M50


Also there is a capsule which could be obtained here which is pretty similar... about as close as we could get... Though it comes with a useless U47 head, which can be discarded or used as a spare for your U47 (if you are a lucky bastard and own one!)

http://shop.flea-microphones.com/index.php?page=productDetail&category=Microphones&prNum=29

So with those two impossible to obtain items in place (at a great cost)... What's next? The tube and transformer... Which I am doing research on as we speak.

-Grant

resurrecting the thread to say that they don't do it any longer...

:'( :'( :'(

Mattia.
 
Resurrecting this old thread....


For our capsule designers:

Here you can find almost anything you need to know about the KK50 aluminium capsule, with great detailed pictures:

http://www.saturn-sound.com/Curio%27s/neumann%27s%20kk50%20-%202nd%20type%20k50%20capsule.htm

The backplate has 91 holes

Kk50%202v%20-%20capsule%20backplate%20-%20pic'.jpg


Kk50%202v%20-%20capsule%20backplate%20ass'%20-%20pic'.jpg


Everything about the whole construction:

http://www.saturn-sound.com/Curio%27s/neumann%27s%20kk50%20capsule%20assembly.htm

Let's hope someone will try to make some great M50 style capsules again!!

 
Bump, as I'm really interested in this, now that bodies are available and I'm thinking these Beesneez bodies I have now are just calling to be M50-types instead of the M49-types I was originally planning for!
 
Still interested in M50 style mics...
Are there any drawbacks using 1/2“ measurement capsules because of their low capacitance of
about 19pF and high output of 50mV/Pa with a Neumann-style circuit? I have a pair of spare MK221 capsules here....

 
Marik said:
AFAIK, there is no... at least readily available. I think Allegro, though, sells selected for low noise tubes of any type--expensive, but might be a good option.

The late Oliver Archut suggested the 5840 triode connected... I have used the 7586 nuvistor triode and the 5703.  All of these tubes have 6.3 volt heaters.  Another one I want to try is the Russian 6S6b subminiature triode.  Neumann used the 7586 in the U64 mic.  Philips sold mics in the USA for AKG in the day which used the 7586.

Note in the M49B, the AC701k triode is biased from the heater supply.  The C version used a resistor/capacitor bypass to ground from the cathode.

I recall the 7586 circuit used a 100 k film resistor from B plus to the plate, and a 3.3 k resistor from the cathode to ground...there was a bypass capacitor (50 uf 25 v hi temp) across the 3.3 k resistor.  The primary of the output transformer connected to the anode (essentially an anode follower).

As for the other tubes, I haven't looked at the load line or run any calculations...
 

Latest posts

Back
Top