M49C circuit details / questions

[k brown]

Wow, you must be mighty picky, or very unlucky; I have 5840 CFs in a couple of Oktava '012 bodies, and they're no noisier than any of my FET mics (more microphonic, though).

6205s, actually; but I doubt they're any different noise-wise.

 

[pasarski]

Wow, you must be mighty picky, or very unlucky; I have 5840 CFs in a couple of Oktava '012 bodies, and they're no noisier than any of my FET mics (more microphonic, though).

This has been my experience as well. My collection is too small for definitive conclusions, but from what I have, my Raytheon 5840Ws are quiet enough. Most are a little bit microphonic, some are not, and a few are too microphonic. The Philips 5840Ws seem to be noisier overall.

 

[Recording Engineer]

I have (9) mics with 5840s in them. They’re not any noiser than any of my (6) with other subminiture tube mics. At least, I haven’t noticed.

 

[telewulf]

First of all I´d like to thank everybody for those great in depth information that you all share here!

I felt a little uneasy that I could not contribute any beneficial stuff in return ... but then I thought, well I just might be able after all, only my contribution would be rather historical than technical.

I started work in 1991 at the NDR which is one of the two succesors of the NWDR that designed the M49 as well as the V72 and oh so many other pieces of equipment. I became deeply attached to this equipmet that was developed in a few drafty sheds in post war Germany an is still held in esteem by the likes of us, even 70+ years later.
I then started spending production-free time and my lunch breaks in the library, going through the in-house-bulletins of said years for historical informations, and it is the articles that I found, that I´d like to share with you. Attached you will find copies of three articles on the M49, in German as well as translated into English.

The first one is from 1950 and is the earliest mention of the M49 in the very first edition of said bulletin. It was written during the construction time and obveously they didn´t even have a name for the M49´s brother (you know, the one with the plexi-sphere because in this article it is only referred to as the "15kHz-Mikrofon". 15 kHz being the magical benchmark at that time, because only the previous year FM radio had been introduced in Germany and the sole reasen for the tremendous upheaval of constructing all this equipment in post-war-Germany was that the frequency range had thus been expanded from 7kHz to 15kHz.

The second article was written when the M49 was released the following year and I find it particularly fascinating, because of the unlikely adendum of the paragraph on "Ersatzlautstärke" (ersatz volume in my translation). This might ad the final pieces to the jig saw puzzle of the M49´s measurement input. It must have been a great idea back then and so gives a glimpse of the many sometimes strange inventions by the NWDR-Zentraltechnik!

The third article is about the creation of the MS2 valve that had to be created especially for the M49/M50 by the small company Hiller in Hamburg, because the big valve-producing companies were unable to fullfil the task at the time.

I hope you find the articles informative or interesting but I´d be happy if they just raise a smile,

Best wishes from Bremen,
Wulf

 

[rock soderstrom]

I hope you find the articles informative or interesting but I´d be happy if they just raise a smile,

Great stuff!

 

[abbey road d enfer]

The first one is from 1950 and is the earliest mention of the M49 in the very first edition of said bulletin. It was written during the construction time and obveously they didn´t even have a name for the M49´s brother (you know, the one with the plexi-sphere because in this article it is only referred to as the "15kHz-Mikrofon". 15 kHz being the magical benchmark at that time, because only the previous year FM radio had been introduced in Germany and the sole reasen for the tremendous upheaval of constructing all this equipment in post-war-Germany was that the frequency range had thus been expanded from 7kHz to 15kHz.

Very interesting, thank you.
It raises a question:
"In contrast to the old microphones, mains voltage operation is planed within the radio houses, whereby each microphone should be assigned to its own dedicated power supply unit."
How was it done earlier? Was there a central PSU?

The second article was written when the M49 was released the following year and I find it particularly fascinating, because of the unlikely adendum of the paragraph on "Ersatzlautstärke" (ersatz volume in my translation). This might ad the final pieces to the jig saw puzzle of the M49´s measurement input. It must have been a great idea back then and so gives a glimpse of the many sometimes strange inventions by the NWDR-Zentraltechnik!

First incarnation of "Ersatzgeräuschpegel" ("Equivalent noise").

The third article is about the creation of the MS2 valve that had to be created especially for the M49/M50 by the small company Hiller in Hamburg, because the big valve-producing companies were unable to fullfil the task at the time.

Very interesting too. It's the first time I see a clear explanation of operation without a grid resistor (as in the Hiller mic).

 

[Migs 31]

I started work in 1991 at the NDR which is one of the two succesors of the NWDR ....Best wishes from Bremen,
Wulf

Ja! Wunderbar !!!
Thank you so very much!!!!

PS: I was in Bremen not that long ago for the Jazz Festival (Not in Bremen - Cuxhaven old Terminal)

M

 

[Khron]

How was it done earlier? Was there a central PSU?

Battery power? Wasn't the U47 meant to (also) operate off a 105V DC battery supply?

 

[abbey road d enfer]

Battery power? Wasn't the U47 meant to (also) operate off a 105V DC battery supply?

Doesn't seem likely.
P48 was developed because many studios in Norway (I believe) already used 48V DC for whatever.
Bur 105V from batteries seems hazardous. And according to the first document, power supplies were introduced from the start, the number of them being dictated by the number of channels on the mixer. So it seems NWDR considered power supplies as fixed items, microphones being nomadic.

 

[kingkorg]

First of all I´d like to thank everybody for those great in depth information that you all share here!

I felt a little uneasy that I could not contribute any beneficial stuff in return ... but then I thought, well I just might be able after all, only my contribution would be rather historical than technical.

I started work in 1991 at the NDR which is one of the two succesors of the NWDR that designed the M49 as well as the V72 and oh so many other pieces of equipment. I became deeply attached to this equipmet that was developed in a few drafty sheds in post war Germany an is still held in esteem by the likes of us, even 70+ years later.
I then started spending production-free time and my lunch breaks in the library, going through the in-house-bulletins of said years for historical informations, and it is the articles that I found, that I´d like to share with you. Attached you will find copies of three articles on the M49, in German as well as translated into English.

The first one is from 1950 and is the earliest mention of the M49 in the very first edition of said bulletin. It was written during the construction time and obveously they didn´t even have a name for the M49´s brother (you know, the one with the plexi-sphere because in this article it is only referred to as the "15kHz-Mikrofon". 15 kHz being the magical benchmark at that time, because only the previous year FM radio had been introduced in Germany and the sole reasen for the tremendous upheaval of constructing all this equipment in post-war-Germany was that the frequency range had thus been expanded from 7kHz to 15kHz.

The second article was written when the M49 was released the following year and I find it particularly fascinating, because of the unlikely adendum of the paragraph on "Ersatzlautstärke" (ersatz volume in my translation). This might ad the final pieces to the jig saw puzzle of the M49´s measurement input. It must have been a great idea back then and so gives a glimpse of the many sometimes strange inventions by the NWDR-Zentraltechnik!

The third article is about the creation of the MS2 valve that had to be created especially for the M49/M50 by the small company Hiller in Hamburg, because the big valve-producing companies were unable to fullfil the task at the time.

I hope you find the articles informative or interesting but I´d be happy if they just raise a smile,

Best wishes from Bremen,
Wulf

So few views of the documents is criminal! Thank you for sharing this

 

[rock soderstrom]

So few views of the documents is criminal!

I don't think the counter is working properly, the numbers don't make sense. I have already noticed this elsewhere...but the documents are premium content, no doubt about it.

 

[telewulf]

Battery power?

Yes indeed. Of couse supply by mains power did exist but was considered inferior because of the audible hum that came with it. So battery supply was indeed the first choice until the N52 came along.

 

[telewulf]

P48 was developed because many studios in Norway (I believe) already used 48V DC for whatever.

I was told that in Norway 48V DC was used for the signaling lamps. Could that be right? Over to you, King Korg ...

 

[kingkorg]

I was told that in Norway 48V DC was used for the signaling lamps. Could that be right? Over to you, King Korg ...

From Wiki:

In 1966, Neumann GmbH presented a new type of transistorized microphone to the Norwegian Broadcasting Corporation, NRK. Norwegian Radio had requested phantom-powered operation. Since NRK already had 48-volt power available in their studios for their emergency lighting systems, this voltage was used for powering the new microphones (model KM 84), and is the origin of 48-volt phantom power. This arrangement was later standardized in DIN 45596.

FWIW, Norwegian NRK seems to have moved entirely to Microtech Gefell. They have brutal budgets, gear, no particular biases, and can afford basically anything available on the market.

I have serviced a number of vintage u87 previously owned by NRK, now in hands of local musicians. NRK doesn't seem to value much u87 these days.

 

[telewulf]

Since this seems to be the ideal place for group efforts, here´s another thought:
I did the translation with the help of some online translator ... the result being hilarious sometimes. I tried to cawrrect that to the best of my abelities, but since I am German, I suspect there will be loads of misused words and misspellings. So I would very much appreciate corrections ... for the benefit of everybody.
Alternative: if any native English speaker would want to correct the text, I could supply an open office file.

best wishes from Bremen,
Wulf

 

[abbey road d enfer]

Since this seems to be the ideal place for group efforts, here´s another thought:
I did the translation with the help of some online translator ... the result being hilarious sometimes. I tried to cawrrect that to the best of my abelities, but since I am German, I suspect there will be loads of misused words and misspellings. So I would very much appreciate corrections ... for the benefit of everybody.
Alternative: if any native English speaker would want to correct the text, I could supply an open office file.

best wishes from Bremen,
Wulf

You've done a very good job of it.
IMO the only thing that may need editing is the "ersatz volume", which is commonly known as "equivalent noise level" (Neumann).
Also known as "Äquivalentschalldruckpegel" (AKG) or "self noise" (Shure).
Although I'm not a germanist, I think the AKG wording is much more accurate than ersatz volume.

 

[telewulf]

IMO the only thing that may need editing is the "ersatz volume"

Thank you, that´s a relief

I was hesitant about that one too. But because "Ersatzlautstärke" is very outdated and must sounds almost comical to younger German ears, I decided to go for an equaly unlikely translation. Well, of course the subtelty of being outdated had to turn out impossible to translate. - *sigh*
So thank you for your suggestion!

 

[abbey road d enfer]

Thank you, that´s a relief

I was hesitant about that one too. But because "Ersatzlautstärke" is very outdated and must sounds almost comical to younger German ears, I decided to go for an equaly unlikely translation. Well, of course the subtelty of being outdated had to turn out impossible to translate. - *sigh*
So thank you for your suggestion!

I think it's worth having a side note mentioning this old-fashioned vocable.
Reminiscent of days where capacitors were condensers, sometimes measured in centimeters, resistors used upper case "omega" for large value and lower case for low values

 

[telewulf]

jepp, you´re propably right - I´ll bear that in mind!

 

[rock soderstrom]

IMO the only thing that may need editing is the "ersatz volume", which is commonly known as "equivalent noise level" (Neumann).

Also known as "Äquivalentschalldruckpegel" (AKG) or "self noise" (Shure).

Yep, Ersatzgeräuschpegel would be the most used german expression nowadays.