R/E/P > Klaus Heyne's Mic Lab

Neumann U67 Reissue: Complete Tear Down and Analysis

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klaus:
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 [email protected]). 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.

harmonyunited:
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 ?

klaus:
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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