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[klaus]

One of the bottlenecks to currently produce a PVC M7 that sounds like a real one (Neumann or Gefell): is the toxic chemical formula that was used until the early 2000s (at least in East-Germany, West-Germany had abolished the material already a decade earlier).

The new stuff has a different, environmentally sound, molecular structure, and somehow that has "colored" the sound differently than the old formula. How else to explain that both MG's and Thiersch's PVC M7 have that same mid-band harshness, no air but a hard ceiling around 7-8 Khz, and inarticulate lows?

I believe both companies do what they can with the PVC they have available. And it's good enough, unless you ever heard a real M7, even only ONCE. Then you can never go back and be satisfied with the current PVC product. And, a consequence of so many people having never heard a real M7 is that they think the current stuff is good and authentic. What a problem to overcome!

[soapfoot]

Then what hope is there for a U47 owner who needs an M7 replacement?

I'll let Klaus weigh in on this, but the Thiersch PVC replacement ("blue line") is an excellent capsule. I used one in a microphone I built for myself and I absolutely love it, and it's captured much of the spirit (to my ear) of the original M7. Probably not identical, but an excellent-sounding capsule in its own right.

[Jim Williams]

China may be an answer to reproducing PVC capsule diaphrams. They don't follow EPA or CE enviromental restrictions there. If Gefell set up a shop there, who knows what could be made? Seems about every other audio company has set up a shop there and if instructed and provided the correct formulas they could be successful.

Mogami is a perfect examle. Their soft, special rubber cable coatings are illegal to manufacture here but not in the far east where enviromental restrictions are not yet in place.

[method1]

I know this thread is old, but I'm wondering if that was a one-off experience or have you experienced a general improvement in k870 capsule quality?

[SergioA]

+1. I feel this deserves some follow up.

[klaus]

China may be an answer to reproducing PVC capsule diaphrams. They don't follow EPA or CE environmental restrictions there.

So their lives and good health are less of a consideration, just because they live far away?

[mikezietsman]

Just a bump for interest.

Klaus - has the post 2012 Era capsule ushered in a step up in consistency of the quality of the k870/k67?

Thanks,
Mike

[klaus]

Thanks for the reminder to update my initial impressions.

As you may know, a constant trickle of factory-new U87Ai come through here- they serve as starting point for my modifications. They also allow me to take the pulse of this model through the years- many tiny changes are continuously introduced in this mic, from the way the attenuation switches are labeled, to the quality of the capsules.

Speaking of capsules: I wish I could report that all is well now, and that an overwhelming percentage of K87/870 capsules is now frequency-balanced and full-bodied in the lower register. They probably all pass Neumann's ±2dB test, but there are still too many of these capsules which take the time-consuming effort to "enrich" their low end far enough, so that the overall sonic impression is no longer harsh, midrange pointy, and congested, i.e. lacking musicality, however you want to define musicality.

The reason why this is so frustrating for me: there are current-production K87/870 capsules which sound extraordinary in their musical and emotional enticement, right out of the box. These capsules are on par with the best that Neumann produced in the early decades of the U87 and its predecessor, U67.

So it's obviously not a systemic issue pointing to a need for a change in design*, but more likely a quality-control or selection issue. I wish I knew how Sennheiser selects and rejects during production, but I don't. But the variable seems to be connected to diaphragm tension, otherwise I would not be able to often dial-in better performance on some of these harsh-sounding capsules by relaxing the diaphragms.

Bottom line: Neumann is still capable of making the absolutely best LD capsules in the world, but it's still too much hit and miss for my taste how individual capsules come out. I wish the company would return to the manufacturing and/or selection methods employed before ca. 2000-whatever they were-when an overwhelming percentage of K87/870/67 was "in the ballpark".

*Stephen Paul once wrote a critique of the new lapping method Neumann started using in the early 1990s (?) which replaced the less-exact gapping between diaphragm and backplate through plastic spacers. I do not believe that that change has anything to do with the quality issues discussed in this thread: Neumann has successfully used backplate lapping for decades without any audible detriment.

[Recording Engineer]

So there is a possibility that this may actually truly be a bean-counting, time is money, kind of issue; be it a sanctioned company policy or simply implemented by a manager?

[klaus]

Yes, that is a possibility, but the general public, me included, would never find out, so I see no purpose in speculating why there is still such range in response from capsule to capsule.

Neumann's Uwe Sattler may chime in here, and remind everyone that his former company still has the tightest tolerance of any capsule manufacturer. That is indeed true. But as I recently posted on another forum, "within spec" is still a 4dB tolerance range from capsule to capsule (±2dB).

I would love more bass in K870, so that most capsules end up on the (+) rather than (-) end of allowable tolerance. Hell, I would even buy Neumann's rejects that fall outside the tolerance on the plus side. Makes my job that much easier.

[Recording Engineer]

I only mention it because it seems everyone always wants to quickly blame everything that's "wrong" on the big-bad-wolf-bean-counter; but here's a real case where it seems to truly be a possibility this time.

[klaus]

The larger picture to keep in mind:
Neumann is the only mic company supplying spare capsules for mics that were first sold in 1951!

So, even if the mercenary aspect may be blamed for the perceived deterioration of some of these capsules, I am grateful that this is not AKG or Schoeps which won't even work on mics that were discontinued only a few years ago. Or try Sony or Microtech Gefell which won't supply parts or service for ANY of its condenser mics-old or new- in the U.S.

[Recording Engineer]

Unless it has changed in the last few years, I believe you can still purchase Sony capsules for C800, 800G, and C38B. I bought a pair of C38B capsules directly from them about 3-years ago. But yes US customer service is absolutely non-existent!

[FoxFoxFox]

Hey Klaus, wondering about buying a 2000's U87. What year were the capsules not sounding right? Thanks.

[klaus]

For the answer please read my opening post #1, and update, #23.