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Author Topic: Neumann M269c.  (Read 14440 times)

David Satz

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Re: Neumann M269c.
« Reply #15 on: April 26, 2004, 01:04:29 pm »

There's enough difference in the frequency response and voltage gain of the U 67 and M 269 amplifier circuits to make them sound different in a careful direct comparison.
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David Bock

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Re: Neumann M269c.
« Reply #16 on: April 26, 2004, 03:20:52 pm »

It should also be noted that the absolute broadband headroom of the 269 is lower, but that the peak distortion component on the 67 is far more complex and offensive (you never get anything for free in audio). In addition, the 269 is a self bias as opposedd to the 67's fixed bias amp, again, affecting peak parameters differently.
So really there are some frequency, dynamic, and distorion differences that we can measure and quantify here.
Then of course there's individual capsule aging...
regards,
David Bock
Soundelux Microphones

Fibes

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Re: Neumann M269c.
« Reply #17 on: April 26, 2004, 03:38:56 pm »

Excellent thread, I love the M269c and now I ask: Can someone tell me where to send my fritzing little beauty for a once over and repair? Feel free to do it by email or PM if you don't want to go on record here...

David,

Can you send me an O ring or two for my U95 shock mount? Sure I could go to the hardware store and get one but it may not be exactly the same. Or give me a part number or something?
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Fibes
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Klaus Heyne

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Re: Neumann M269c.
« Reply #18 on: April 26, 2004, 04:25:24 pm »

Dear Davids (Satz, and Bock)
Thanks for chiming in with your thoughtful responses. This quality of posting will be used in distant futures as reference material.

No problem disagreeing with my opinion. I love it!
But now we have to reconcile the following differences:

1. Davis Satz:
There is zero difference in the amp layout, including eq section, and capsule complement, between original 269 (non-c)  and U67.

That would leave the tube. It is probable that an AC 701 (M269 mic) has a different gain than a EF86 (U67 mic)
But a 2dB variation in lows and highs between different, super high premium quality audio tube types??? Never heard of such. So, where would that deviation come from?

I listened to quite a few of of both mics in my life and cannot confirm the measurement differences aurally.

2. Davis Bock:
Of course, the tube's biasing (the way the tube is primed to perform its operation has a bearing on the timbre and frequency response of  the audio circuit the tube serves)
influences the audio considerably. I thought I made that clear in my post.

Therefore the 'c' version of M49, M269, SMx and KM5x mics will always display a different timbre from the earlier non-c versions.
However, I warn the readers not to infer from this statement that later 'c' versions of Neumann (or other manufactures using cathode self biasing) is automatically  preferable. Try installing the 'c' version in a U67 mic, or a U47 mic, and you will find a black hole where there was beauty before.


Let's never forget how we react emotionally to a mic: The midrange texture of the earlier biasing is hard to beat, even as self biasing lowers the noise floor and makes the picture more transparent, something is given up.

Kind regards,
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Klaus Heyne
German Masterworks
www.GermanMasterworks.com

David Bock

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Re: Neumann M269c.
« Reply #19 on: April 26, 2004, 05:10:30 pm »

"That would leave the tube. It is probable that an AC 701 (M269 mic) has a different gain than a EF86 (U67 mic)
But a 2dB variation in lows and highs between different, super high premium quality audio tube types??? Never heard of such. So, where would that deviation come from?"
The plate impedance of the AC701 is not identical to that of the EF86, therefore under reflected load condition (actual use) they will not load to the BV12 indentically, causing deviations at thje extreeme ends of the frequency response. This is classic textbook behavior for tube to xfmr loading, see The Radiotron Designer's handbook for a full discussion.
In addition, the gain of the individual tube used in Bore's circuit will influence the PFB and NFB behavior- slightly! This means that not only will individual tubes with different gains will result in different output levels, but the HPF and LPF's will be slightly different in slope.
Listeningwise, I can say that the M269 was the first mic I used when I started pro recording at age 18, and my memory of it was that it was not as "hard" sounding as the 67's I ended up using in subsequent years.
-DB

Klaus Heyne

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Re: Neumann M269c.
« Reply #20 on: April 26, 2004, 05:43:11 pm »

dbock wrote on Mon, 26 April 2004 14:10


Listeningwise, I can say that the M269 was the first mic I used when I started pro recording at age 18, and my memory of it was that it was not as "hard" sounding as the 67's I ended up using in subsequent years.
-DB


I agree.
I attribute it to the AC701's dynamic characteristics.

Thanks for the explanation of frequency repsonse vs. tube plate load/transformer response.  Maybe this is indeed the reason for the slight variations in the extreme frequencies beween the two mics.
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Klaus Heyne
German Masterworks
www.GermanMasterworks.com
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