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Author Topic: Neumann U67 Reissue: Complete Tear Down and Analysis  (Read 89577 times)

RuudNL

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #135 on: May 27, 2022, 08:52:21 AM »

Funny that people (think to) hear a difference between different cables. When I was still working for a radio station, we had two kinds of cable from the same manufacturer. One kind was black, the other kind gray. A colleague claimed that the gray cable sounded 'better' and even hid cables when he had to make an important recording the next day.
My idea: he had once made a good recording and used gray cables. From that moment on, he was convinced that the success was due to the gray cables...
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klaus

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #136 on: June 22, 2022, 01:14:44 PM »

I cannot comment on the specific case you cite, but do not underestimate the role a dye in the cable jacket can make in affecting the electrical properties of a cable.
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Klaus Heyne
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RuudNL

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #137 on: June 23, 2022, 06:09:09 AM »

What could be an explanation that the outer jacket of the cable could affect the audio quality?
The outer jacket lies outside the shielding layer, so no effect could be expected from this.
(This reminds me a bit of people buying an expensive cable between their CD player and the amplifier; low output impedance, high input impedance, resistance and capacitance of the cable are negligible. And yet people who buy a $100+ cable, now called an 'interlink', -sounds more impressive-, say: "it sounds better now". I suppose they want to hear the money that is no longer in their wallet...)
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klaus

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #138 on: June 23, 2022, 02:33:39 PM »

Jackets measurably affect capacitance, reactance and likely other, less obvious electrical parameters of an audio-carrying cable.

Without getting into the philosophy of perception vs. delusion, I can cite conversations with a major cable manufacturer who, after realizing the new jacket material was no longer amenable to the sound envisioned, reversed the jacket material to the previous design, dimension (and dying) and all was well again.

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Klaus Heyne
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Paul Johnson

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #139 on: July 22, 2022, 12:18:08 PM »

Reading all this made me think. I am one of those who have 'trouble' with the flowery words used to describe audio, but here, I do understand what Klaus means because his pick of descriptive words does click in my brain. Clearly, he hears differences, and measurements fail to make sense with this study. The only issue is one of understanding. When any of us see a certain colour of blue, we have no way of determining if another viewer sees the same colour - we just call what we see, blue. Mine might be pink, who knows?  Here, the differences he hears make sense. The facts seem to be that there are differences, good ones and bad ones. Pointing the most critical ones out - as in the capsule and tube also makes sense. The sad bit is that Neumann give him a mic yet gave him one less good, as a re-issue. Surely they should have heard the same? The question is why did they not, as they didn't;t in the past with the capsule performance being 'in-spec' - what exactly does being in spec mean, if a less good one is technically OK?

As I said, I usually hate all those emotive words people use, but coming from an expert, they're actually OK, because they have context. 

It's a bit sad a prestige microphone that clearly could be wonderful didn't really get listened to by the manufacturer?
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klaus

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #140 on: July 22, 2022, 01:55:11 PM »

Your excellent points responded to, one by one:

1. I am one of those who have 'trouble' with the flowery words used to describe audio
The trouble is universal: describing any sensory impression - touch, sight, hearing, smell, taste - defies objective, scientific measurement. Any of these impressions need translation from our subjective realm to an objective, quantifiable and measurable reality., So we use rather personalized language to communicate what we experience.

And, because differentiation and refinement of language, in this case, language describing recorded sounds, does not happen overnight (recoding is barely a century old), describing what we hear still seems clumsy and awkward at best.

However:

2. Here, the differences he hears make sense. The facts seem to be that there are differences, good ones and bad ones.
The differences are not only audible, but in the case of "owe-end starved" capsules, like the one of the test object, also measurable. The problem: Neumann uses a ±2dB tolerance within which a mic (in this case, mainly a capsule) has to perform in oder to be signed off. I had submitted bass starved capsules to Neumann in the early 2000s, an d they were plotted in Neumann's fabulous anechoic chamber in Berlin. And the low end was indeed at the very limit of that tolerance (down a hefty 3.9dB@50Hz). That is not only measurable but will be detected by any ear.

Now comes the hard part:

3. The sad bit is that Neumann give him a mic yet gave him one less good, as a re-issue. Surely they should have heard the same? The question is why did they not, as they didn't;
As stated in #2: the mic was within Neumann-designated specs. So now a larger issue looms: if any mic performs as spec'd, that's the end of the line: there are no taste masters in some man cave in he basement of the assembly lines in Wedemark who then warms up each U67 for an hour, listens to each mic to make sure it "sounds" good. That is simply not on possible in mass-manufacturing.

So, what did change, and could it be changed again, to eliminate the problem once and for all?

4. in the past with the capsule performance being 'in-spec' - what exactly does being in spec mean, if a less good one is technically OK?
A relevant factor in capsule manufacturing: how many rejects can be absorbed before it affects the bottom line? A higher diaphragm tension eliminates almost all such rejects-no bottoming out, no popping, no catastrophic failures from electrostatic attraction, no shorts, especially in high humidity markets (South East Asia, etc.) So, increasing diaphragm tension which has objectionable sonic effects, also makes production less fail prone: warranty returns are costly and always lossy.

I talk to the powers that be at Neumann frequently. They value my input and are taking the constructive criticism I voiced in my original teardown of the U67RI serious. They do not only know the problem, but, especially with the new management and its more dynamic attitude in place, I am optimistic that the bass-starved capsules will some day soon be distant memory.
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Klaus Heyne
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harmonyunited

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #141 on: November 16, 2022, 05:44:21 PM »

First of all, this is such a wonderful thread to read! Thanks Klaus for the breakdown and write up. Very helpful for me…

I am the proud new owner of a reissue u67. I’ve already sourced a nos ef806s that sounds quiet and so detailed and rich. Very happy with this. I’m also going to be getting the capsule diaphragm tuning from Klaus in the near future when I save up enough buffer funds.

However, one thing about the reissue that I was NOT impressed with was how messy the PCBs were with sputtered flux everywhere and with excess flux residue on the joints in general. Wiring, although functional, did not please my eye either. I would think they for a product this premium that the techs who assemble these would take more pride with the aesthetics of internals… maybe there is another explanation for leaving flux residue everywhere?

I remember cracking open a Brauner; the pcbs were immaculate and wiring very tidy too. You’d think Neumann would be the same…

Does anyone have reflections about this ?
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klaus

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #142 on: November 16, 2022, 09:30:20 PM »

Everybody needs feedback - to improve the quality of our daily existence, reduce friction and misunderstanding with others, and to improve the services and products we purchase. I am a firm believer in this, despite the blowback, prejudice, and stereotyping I sometimes get ("so German...").

I had noticed a slackening of manufacturing quality of discrete-component mics like the U87Ai and U67 Reissue. Specifically, soldering joints and wiring terminations were sometimes sloppy and less than what I am used to from Neumann. This seemed to be concentrated on mics made during the heights of Covid.

I mentioned this to the management of Neumann and was informed that the company was so short on assemblers during the pandemic that they had to train management and non-specialists to step in for a while to work the manufacturing lines.
The trend seems to have ebbed now, despite the occasional assembly faux pas here and there.

I encourage you to contact Neumann's head of development, Martin Schneider ([email protected]), and let him know what you found. I see no negatives in speaking up, especially when you deal with a company that takes great pride in having probably the highest manufacturing quality of any microphone company in the world.
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Klaus Heyne
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SDVIG

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #143 on: March 10, 2023, 04:59:28 AM »

Hello. I recently purchased a Neumann U67 set.
Serial number 73999.
I have two questions:
1) Does it come in a cardboard box?
(I received the case in a cellophane film and separately in a cardboard power cable)
2) When I opened the microphone, I did not see a blue protective seal on the head of the grill,
on one of the three screws.
I've seen this before on the U87.
Neumann don't put a protective seal now?
Thanks for answers.
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klaus

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #144 on: March 10, 2023, 01:33:26 PM »

Hello Sergey, answering your questions in order:

1. At least in the U.S. and (AFAIK) in Europe, U67 Reissues are only sold in a suitcase (see pic), containing the mic (wrapped in a plastic bag) the cable (wrapped in a plastic bag) the NU67V power supply (wrapped in a plastic bag) and user manual (wrapped in plastic bag, as we need still more plastic bags to save the oceans!) and the Neumann suspension mount, not wrapped in a plastic bag.

These items are placed in a black form-fitting tray inside the suitcase. There is no additional box or cardboard for the mic itself.

2. Every KK87Ai an KK67 head has a wax seal on of of the three head assembly screws when it leaves the factory.
However, sometimes the wax used is clear., not blue. So, after you remove the screws, look really close for wax remnants in the wall of the head's plastic molding where the screw is mounted. There are always remnants. If you see wax there, you know someone had previously opened the head.


P.S.: Compare serial number on the mic with serial number scribed into the bottom of the head, as shown. They should be the same.
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Klaus Heyne
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SDVIG

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #145 on: March 11, 2023, 05:30:53 AM »

Klaus, thanks.
Found a couple of videos on youtube:

https://www.youtube.com/watch?v=WB5ZAIOV6Pk&list=LL&index=17

https://www.youtube.com/watch?v=P0qRZamthFM

If you look at my photo, there is no protective seal.
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klaus

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #146 on: March 11, 2023, 11:41:56 AM »

Both videos show how the mic comes from the factory: plastic wrapped in the form-fitting tray inside the suitcase.

If your mic does not have the protective wax seal on the head, there are only two possibilities:

1. someone had opened the head, and Neumann likely will not honor its one-year warranty for the mic.
2. someone forgot to put the factory seal on (this would be a first)

Open the head
(https://germanmasterworks.com/publish/articles/Advice/Step-By-Step-Instructions-On-How-To-Open-A-U87-Head-%28Same-as-U67%29.html
and make sure that you have the original capsule inside (it should be dated "21" or "22").
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Klaus Heyne
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SDVIG

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #147 on: March 12, 2023, 05:22:58 AM »

Klaus,Thank you very much.
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Marcel9206

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #148 on: May 02, 2023, 04:25:29 AM »

Hello,

I'm considering buying a U67 reissue, but then I would like to have the capsule tuned the way Klaus suggests tuning it. I would also replace the tube with a good NOS one. But since I am in Belgium and Klaus is in the US (am I right?), it would be a pricy and risky thing sending over the U67... Do you know anyone in Europe (I'm in Belgium) who is capable of this? I've heard Siegfried Thiersch in Germany is very good working on vintage capsules? Anyone any experience?

Or do the current U67 capsules already sound better? And is it worth spending 6.000 euros on a new mic that still needs a serious upgrade to turn it into a better mic?

Any advice most welcome! Thanks!
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RuudNL

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Re: Neumann U67 Reissue: Complete Tear Down and Analysis
« Reply #149 on: May 02, 2023, 05:53:16 AM »

FWIW: I own two U67 reissue microphones and they sound and measure great 'out of the box'.
So why not try them first before taking more expensive options?
It is easy to change the tube yourself, if you want to.
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