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)

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?