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Neumann U67 2018 reissue internal View
Old 4 weeks ago
  #1021
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toledo3's Avatar
 

Al Schmitt, Bob Ohlsson, and many other credible people, who have *actually used the mics to RECORD MUSIC with*, say the new ones sound like their old ones.

Last edited by toledo3; 4 weeks ago at 03:08 PM..
Old 4 weeks ago
  #1022
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Who here has tried a NOS tube in their 67?

Anyone else using it with a Pultec to add highs and lows?
Old 4 weeks ago
  #1023
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Quote:
Originally Posted by chessparov2.0 View Post
I found I have the same taste aesthetic/concerns as Klaus, when it comes to an original Primo U67, versus the new U67 reissue.

Having said that, I'm also in agreement with JJ Blair's current over all assessment, of what I would call... "Capsule tolerance/Tube concerns".
Some of the current U67 RI's, are a bit "bass shy" for example (compared to an original/or "in spec" U67RI)-But still a great microphone.

But I'd have a Pro Buddy go with me, to Vintage King (or wherever), to go get a new U67.

Still glad the relatively more affordable U99, is just as good (great) though!
Chris
Its the tube. Spend $50 on an NOS Amperex. All that low end will come back. I've played with a couple of the RI's. It's all in the tube. The capsule simply makes them a little more mid forward, but was not the source of the bass loss in the ones I tested. I was swapping heads with vintage 67's for testing, btw. I did not hear bass loss in either capsule.
Old 4 weeks ago
  #1024
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Klaus's Avatar
 

Quote:
Originally Posted by jjblair View Post
Its the tube. Spend $50 on an NOS Amperex. All that low end will come back... I did not hear bass loss in either capsule.
J.J., I am surprised by your absolutist statement, based on listening to...2 capsules? Lucky you!

As this is the same capsule used in U87Ai, I can tell you from hundreds tested that I wish it was so. Granted, there are great K67/870 right out of the box, even today, but by and large, the roundness, sweetness, fullness we all expect of a K67 is not that easy to find anymore.

I fully agree on the tube issue and had mentioned that as well in my 2018 review: there are no redeeming qualities in that Russian POS, but fortunately that's a fairly inexpensive fix.
Old 4 weeks ago
  #1025
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Quote:
Originally Posted by Klaus View Post
J.J., I am surprised by your absolutist statement, based on listening to...2 capsules? Lucky you!

As this is the same capsule used in U87Ai, I can tell you from hundreds tested that I wish it was so. Granted, there are great K67/870 right out of the box, even today, but by and large, the roundness, sweetness, fullness we all expect of a K67 is not that easy to find anymore.

I fully agree on the tube issue and had mentioned that as well in my 2018 review: there are no redeeming qualities in that Russian POS, but fortunately that's a fairly inexpensive fix.
Klaus, I always defer to you in these matters. I had actually thought you said they were more consistent these days, so if they’re not then forgive my misstatement.
Old 4 weeks ago
  #1026
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I hesitate to tread, but...

If the hypothesis is supposed to be that Neumann is making capsule with more tension, how is that supposed to be occurring? Is the claim that they have literally changed the weight of the ring that provides the downward tension during assembly? Is the claim that they have literally changed this weight value, and thus the capsule also is now being built with an aim towards having an officially different resonant frequency? If that is not actually true then the claim doesn’t hold water.

It makes a lot more sense to me that if there is any variability, that it would be happening in the mylar preparation, because it is just the area where there is inherently wide tolerance ranges in the initial product prior to pre-aging. This is an interesting, old, post where David Josephson goes into this issue of mic manufacturer, explaining the inherent variability of mylar, especially when used at its limits as it is in mic. How it sometimes unpredictably tightens, loosens, etc:

https://groups.google.com/d/msg/sci....g/9GFopaglEMUJ

Here is some some more interesting info about mylar issues from thiersch (second to last paragraph particularly relevant):

https://www.thiersch-mic.de/en/estm_faq1.html



It seems if someone somehow gets an “off” cap, that they should actually return the mic for service, because it should be possible for Neumann to determine whether the resonant frequency is correct or not. It always feels like you learn something by actually letting a company fix a problem if it exists.
Old 4 weeks ago
  #1027
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Quote:
Originally Posted by jjblair View Post
I had actually thought you said they were more consistent these days, so if they’re not then forgive my misstatement.
Correct. Extreme cases of diaphragm hypertension that I encountered in late 2017/18, and in the U67Reissue I tested and wrote about are getting rare.

It's the average that still concerns me: too many people continue to send me current-issue capsules to reduce the tension back to 1960s level. It's time-consuming and not lucrative, but an interesting project I continue to refine and improve.
Old 4 weeks ago
  #1028
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Thanks guys.

BTW as a side note, in the prior post that mentions the Chandler TG... IMHO that microphone handles sibilance (like mine around 6.5 Khz) quite well.
There are so many tonal options on it though, it could be a little tricky to find the right setting sometimes.
Chris
Old 4 weeks ago
  #1029
Quote:
Originally Posted by Klaus View Post
Correct. Extreme cases of diaphragm hypertension that I encountered in late 2017/18, and in the U67Reissue I tested and wrote about are getting rare.

It's the average that still concerns me: too many people continue to send me current-issue capsules to reduce the tension back to 1960s level. It's time-consuming and not lucrative, but an interesting project I continue to refine and improve.
Couldn't the actual overtension be how it was on stock vintage units? Wouldn't the tension loosen over a period of 50 years?

It's always interesting to hear someone with allot of experience speculate on why the vintage units are like they are aka superior to pretty much anything made today. Is it tension loosening, components and values changing or just simply superior build quality?
Old 4 weeks ago
  #1030
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I'd be curious to know what current production numbers are vs a typical year of original U67 production. Is the capsule tensioning process something that Neumann are trying to automate? Manufacturers have a complex algorithm they can use for % tested vs % possible to be out-of-spec (or defective, in a binary world); I would think that QC in the original run was made by experienced technicians on a 100% basis, and it would be interesting (and possible it's done the same way now) to know how current manufacturing and testing is carried out.
Old 4 weeks ago
  #1031
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Quote:
Originally Posted by myles View Post
I'd be curious to know what current production numbers are vs a typical year of original U67 production. Is the capsule tensioning process something that Neumann are trying to automate? Manufacturers have a complex algorithm they can use for % tested vs % possible to be out-of-spec (or defective, in a binary world); I would think that QC in the original run was made by experienced technicians on a 100% basis, and it would be interesting (and possible it's done the same way now) to know how current manufacturing and testing is carried out.
No, they don’t automate the process of tensioning. The main thing different from the old days is actually the process of creating the backplate.

Here is some footage of a capsule being tensioned. The mylar is actually mounted on a large metal ring when the gold is sputtered on the area where the diaphragm will be. That same metal ring is what provides the downward tension.

https://youtu.be/RTZy-ThRXeY

Old 4 weeks ago
  #1032
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Quote:
Originally Posted by toledo3 View Post
No, they don’t automate the process of tensioning. The main thing different from the old days is actually the process of creating the backplate.

Here is some footage of a capsule being tensioned. The mylar is actually mounted on a large metal ring when the gold is sputtered on the area where the diaphragm will be. That same metal ring is what provides the downward tension.

https://youtu.be/RTZy-ThRXeY

Thanks, helpful and interesting.
Old 4 weeks ago
  #1033
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This is an excerpt from the mag Studio Sound, from the 80s about some of the construction and testing, though I think Neumann has used the same bit in later literature as well.
—-


Capsule Building – A Science in Itself

The performance of the condenser microphone, now manufactured in an extremely wide range of models, remains largely reliant on the precision engineering involved in capsule production.

The common centre electrode found on a double diaphragm capsule contains a large number of critical drill holes, some of which are blind. The depth of these blind holes determines the volume of air trapped behind the diaphragm. This volume, which inhibits the movements of the diaphragm, determines the transducing ca of the condenser microphon

The dimensions of the holes, and their accurate machining becomes even more crucial when the electrode is produced in two halves. With this design the two halves of the capsule can be electrically connected, and similarly separated, by means of an isolating intermediate layer, thereby making it possible to switch the directional characteristic with the available polarisation voltage.

To smooth the surface of the electrodes two different processes are employed. For microphone capsules whose surface lie on one plane a lap- ping process can achieve a surface flatness of 0.3 μm and a plane parallelism of +/– 1 μm between the front and the back of the electrode. In some cases a capsule’s surface may be in two planes. This may be because the distance between the diaphragm and the electrode has already been determined by the second plane of the electrode. In such cases the finishing is performed on special lathes.

After lapping or lathe finishing, the holes must be deburred, followed by a visual inspection using a powerful microscope.

Diaphragms are made from a 6.3 μm thick polyester foil, such as Mylar. This is first attached to brass rings, then put into a container which holds it while gold is applied under vacuum to a uniform layer 300 Angstroms thick (0.03 μm). The external diameter of the capsule is approx- imately 34 mm. The diaphragm is fitted approximately 40 μm in front of the electrode and is 6.3 μm thick. When a sound pressure of 1 Pa is applied the diaphragm movement is no more than 10 nm. By comparison, the wavelength of violet light is 400 nm.

The mechanical advantages being achieved under these microscopic proportions is best put into perspective by illustrating thus: if a microphone capsule were to be given a scale on which the amplitude for 1 Pa were represented by 1 mm the capsule under manufacture would have to have a diaphragm spacing of 4 m, and the diameter of the capsule would be more than 3 km.

One type of capsule, the KK 88 from the KM 88 microphone, uses pure nickel as the diaphragm material 0.0007 mm thick (0.7 μm).

On assembly of the capsule aluminium foil spacer rings, 40 μm thick are attached to the middle and the edge of the electrode. The lead-in contact for the polarisation voltage is fitted in the centre. This is an assembly device that enables the capsule to be directly connected to a test instrument, with which the capacitance is measured and the mechanical strength of the diaphragm tested. This is done by measuring the change in the basic capacitance after the polarisation voltage has been applied.

Quality Must Be Measurable

To meet the operating conditions encountered in the studio the microphones are subject to testing throughout their manufacture. The capsules alone undergo more than 50 different tests before final assembly.

Since the very beginning in 1928 Neumann condenser microphones have always operated on an audio frequency circuit, with the capsule consequently acting as a very high-impedance generator, rendering it highly sensitive to moisture. And as moisture represents one of the most common operational hazards of a warm recording studio, Neumann has paid great attention to all aspects of insulation.

Quality control devoted to this aspect includes a moisture chamber, in which capsules are placed until both the diaphragm and microphone body are dripping wet. Even under these condi- tions insulation resistances to the order of 20 x 106*Mohms are measured in the capsules.

Another test is to cool the microphones to slightly above freezing point and then place them in a chamber with 100% humidity, at a relatively high temperature. The spontaneous moisture formation that follows infiltrates not only the capsule but the entire electronic circuitry. It would have to be an extremely uncomfortable studio to recreate such conditions to say the least, but just in case, we would like to point out that every type of Neumann condenser microphone will pass this test.
Old 4 weeks ago
  #1034
Quote:
Originally Posted by AuldLangSine View Post
I have a new reissue U67 coming soon. Is there anything that someone like me-- with experience with the vintage U87 but not with any U67-- can do to determine if the mic would improve with retensioning and/or a different tube (and maybe something else)? Is there anything simple I can do to measure frequency response without expensive equipment? (I am more of a musician than a technician. Sure, some people are both equally.) Just trust my ears? I am getting the 67 because while I do like it a lot for vocals-- it really cuts through, it's just too sibilant for my voice. Thanks
If we're talking vintage u67 vs u87 the u87 is a bit more open a bit thicker around 400hz while the u67 is a bit more mellow in the mids. A bit more 800hz and that lowpass in the highs. A u67 should sound extremely smooth almost ribbon like in the mids.

Someone here said something like the u87 is like a photograph, clear and real. A u67 is like an oil painting very flattering and 3d.


Would be interesting if you could post some clips when you have both at your place
Old 4 weeks ago
  #1035
Gear Maniac
Quote:
Originally Posted by toledo3 View Post
Al Schmitt, Bob Ohlsson, and many other credible people, who have *actually used the mics to RECORD MUSIC with*, say the new ones sound like their old ones.
I've only used an original u67 but I'll try renting the newer one and compare.
Old 2 weeks ago
  #1036
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MREVOL's Avatar
 

Would someone mind posting pic of the S2 wire to snip to bypass the low filter.

Also, without going through all the pages of the thread, any recommendations on tubes that you guys love?

Thanks
Old 2 weeks ago
  #1037
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Klaus's Avatar
 

Please specify original or reissue. Original used bare monofilament wire, reissue black-jacketed multi-strand.
Old 2 weeks ago
  #1038
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Sorry, just got a reissue
Old 2 weeks ago
  #1039
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brewbacker's Avatar
 

Quote:
Originally Posted by RoundBadge View Post
Klaus worked on my R.I. capsule
I lifted the lf filter.takes 3 minutes to unsolder.
Sounds great
Had a pair of u99’s
Good but not the same
Much brighter in standard mode
Also used the hf rolloff on vx
Same here, I had a u99 years ago and it was pretty good, but greatly prefer the u67RI. I also had the capsule worked on by Klaus. Definitely not the same as a u99. u99 is workable though.
Old 1 week ago
  #1040
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Callison's Avatar
S2

This is how I dealt with mine, not a re issue but you get the idea
Attached Thumbnails
Neumann U67 2018 reissue internal View-img_5686.jpg  
Old 1 week ago
  #1041
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toledo3's Avatar
 

This article sort of shows some of the issues there would be in trying to retension a diaphragm. It is basically a non starter. http://www.audioimprov.com/AudioImpr...ake-apart.html

Temperature or moisture could have unpredictable results, as laid out by Josephson in the quoted part above. Maybe could work?

It seems that the thing that could be done is to mess around with the spacer and try to make the air cavity slightly larger.

Sub bass is a funny thing, in that in most contexts an inch or two either way from the source can yield noticeably different results via proximity effect, especially in rooms that aren’t particularly acoustically perfect.
Old 1 week ago
  #1042
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toledo3's Avatar
 

It doesn’t change the answer to the question above about where the jumper is, whether the jumper wire is different material or not...it is in the same place either way. It is right behind the tube, and marked by S2 being printed right by it on the circuit board.
Old 1 week ago
  #1043
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Quote:
Originally Posted by Callison View Post
This is how I dealt with mine, not a re issue but you get the idea
Can I get more details how you did a switch? Is this something a noob could do on a new reissue?
Old 1 week ago
  #1044
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Callison's Avatar
I got Gunter Wagner to do it here in Aus, send it to an expert!

Quote:
Originally Posted by MREVOL View Post
Can I get more details how you did a switch? Is this something a noob could do on a new reissue?
Old 5 days ago
  #1045
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toledo3's Avatar
 

How would one change tension on an assembled capsule *diaphragms* in a way that maintains the front and back of the capsules matching, and thus polar pattern uniformity? Is it even really possible given the way the capsules are constructed at the factory?

If Neumann makes many sides of diaphragms to match them together for uniformity, so that polar response is as perfect as possible front to back, any manipulation of the diaphragm would have to have the exact same result on each side of the diaphragm in order to avoid a negative impact on polar patterns.

The inner air gap could be changed without tweaking the diaphragms.
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