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[klaus]

"Eine Schwalbe macht noch keinen Sommer", the saying goes (one swallow does not a summer make), but what I just experienced is quite astonishing, given the sorry state of Neumann K870/K87 capsules of late:

Tonight I installed a brand-new K870 (build date late 2012), and my jaw dropped:

Both sides of the capsule are lush, reedy, frequency-balanced, with a full-figured bass, and are extraordinarily musical. Only the very best K67 from the mid 1960s (the famous 'fibre board' model) could hold a candle to this one. This capsule was so exquisite and similar on both sides (very rare, for any LD dual-membrane capsule, from any period) that I still don't know which of the two sides to make the front side for cardioid operation.

I am hoping and praying that this is a trend, and will report what the next new K870 capsule portends.

Disclaimer: the electronics of the U87Ai which I installed the capsule in are heavily modified; so while this capsule could mitigate some of the stock U87Ai's electronic compromises (which I find especially unsatisfying since circuit diagram 05), it cannot overcome them all.

[soapfoot]

Klaus, this is great news. I really appreciate your sharing of your experiences with things like this-- you see far more of these capsules than most of the rest of us do, so it's good that you keep us abreast of developments. Please let us know if you see evidence of this as a trend (as opposed to an anomaly).

[Jim Williams]

Those '05 SOIC daughter pcb preamps do really sound poor. Best case is to remove that and re-populate the identical pcb with original design components, not too hard to do.

[klaus]

Agreed. And simple enough to do (see previous discussions about how too).

[soapfoot]

I installed a brand new K67/K87 capsule in one of our three U67s yesterday. The old one had a wrinkled rear diaphragm and severe gold loss on both sides (though the front side, interestingly, still sounded fine!)

Once we've used all three for awhile, I'll return to give my impressions of the sound of the new K67 capsule to see if my impressions are positive relative to the other, older K67s in our other two mics.

[soapfoot]

The early 2013 Neumann K67 we installed in our third U67 a couple of weeks ago sounds (so far) very much like our other two U67s (with original capsules).

It's possible that my ear is not as discerning as Klaus's, and it's possible we need even more time to evaluate before an undiscovered subtle difference manifests itself, but... thus far, impressions of this new Neumann capsule are very favorable-- it does not seem inferior in any way to our other U67s.

[NelisB]

Hi Klaus,

Was the capsule you reviewed a K870/K67 (three wires) or K87 (four wires) capsule? My friend just ordered one, he could choose from a 3- and a 4-wire type. I guess that has to do with the isolated backplates?

Thanks, Niels

[klaus]

It's clear from my post you cited that I was referring to a K870/67 (three wires), not a K87 (four wires).

There is no build difference between the two types of Neumann double backplate capsules. They always sounded similar in any given era.

The type of lead-outs or the backplate spacer configuration (aluminum-conductive, or plastic-non-conductive) does not affect the sound, though it could be argued that the lower polarization voltage applied to a K87 will ameliorate the harshness of the capsules of that era I was complaining about.

[NelisB]

Hi Klaus,
About a year ago Ben Sneesby wrote me that one of the reasons for the "inferior' sound of the U87ai, (next to the electronics) is that the diaphragm tension is too high. Do you think it's possible that a lowered tension of the diaphragm causes the renewed sound of your new K870?

Have you used more K870's in the meantime?

Thanks, Niels

[klaus]

It is my opinion that the diaphragm tension causes most of the hardness in the mids and the lack of low end. There are secondary issues with the quality of late model U87Ai sub-boards (starting with circuit #04) but as soon as you pop in a good capsule, even in a brand-new mic, half of the problems are gone.

I have not installed enough recently made capsules to have a firm opinion whether the tension issue has been solved*, but if the trend of the ratio of frequency-balanced capsules to hard-sounding capsules continues, we are on the right track. I will report back when I have enough of a statistical sample to generalize with confidence.

*for those with little time to read on: as of February 2021, the tension problem has not been solved.

[NelisB]

Hi Klaus,

Thanks for your reply.

I have two U87ai's that I hardly ever use because of non-musical sound. Rens Heijnis already changed the electronics what made them better, but still they dont make me smile. I guess your 80% must be the right figure. 

An option I am thinking about is -instead of buying new expensive capsules- is to get my capsules reskined by Thiersch. Can you recommend reskinning? Maybe Thiersch can also get the capsules matched.

Thanks, Niels

[soapfoot]

I've never heard a re-skinned Neumann capsule that actually approached the sound of a good Neumann.
I've heard one of Mr. Thiersch's excellent M7-style rebuilds, and it sounded to my ear very much like Thiersch's excellent new capsules, but (especially being the Mylar version) it did not sound exactly like a good vintage Berlin M7. I've never heard his take on the U87 though.

We once were auditioning some FET 47s, and one had the capsule re-skinned by another very reputable person (not Thiersch-- I won't mention the name). It was so far inferior to the mics with original capsules (despite being in equal or better overall condition) that it was returned despite being significantly lower in price.

By the way, the early 2013 era K67/K870 we installed in our third U67 has been in heavy use, and nobody has once commented that it sounds significantly different (certainly not inferior) to our other U67s (which have original 1960 era capsules). All three have good Telefunken EF86 and are used completely interchangeably-- nobody has picked any of the three as "favorite." This is a testament to the sound of the new capsule, in my mind. Mission accomplished, as far as I'm concerned.

[klaus]

I am in agreement about the uniformly inferior performance of third-party diaphragms mounted on Neumann capsules.
And I can offer first-hand experience with Thiersch-reskinned K870/67: They do not represent the Neumann sound, or even an alternative sonic interpretation that, in its own way, would sound equally or more pleasing than an original Neumann K87/67.

I would also be suspicious when someone offers re-diaphragmed capsules that were restored to supposedly "Neumann specifications" by these third-party providers (Neumann does not offer re-diaphragming services).

[NelisB]

Brad and Klaus,

Thanks a lot for your info!

Best, Niels

[hasbeen]

I've never heard a re-skinned Neumann capsule that actually approached the sound of a good Neumann. I've heard one of Mr. Thiersch's excellent M7-style rebuilds, and it sounded to my ear very much like Thiersch's excellent new capsules, but (especially being the Mylar version) it did not sound exactly like a good vintage Berlin M7.

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