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R/E/P => Klaus Heyne's Mic Lab => Topic started by: aremos on January 09, 2018, 11:32:10 pm

Title: Neumann reissues the U67
Post by: aremos on January 09, 2018, 11:32:10 pm
Note: this thread was started before the mic was issued.
A few weeks later I reviewed and tested the U67 Reissue in great detail. Read it here:
https://repforums.prosoundweb.com/index.php/topic,37307.0.html



As in the 90's, Neumann will once again put out the U67.

Hopefully, like the 47Fet, it will be an exact replica - including the PS, which I believe David Bock had mentioned was the only part of the 90's reissue he wasn't too happy with.
Title: Re: Neumann reissues the U67
Post by: DigitMus on January 10, 2018, 12:12:34 am
Any link or sources on this. Have heard nothing myself.
Title: Re: Neumann reissues the U67
Post by: klaus on January 10, 2018, 03:02:53 am
Nothing concrete yet, except this promo.
Never mind the power supply. The trick will be the tube: U67 are super picky: only NOS EF86 will do, and even then it has to be the right kind.
Title: Re: Neumann reissues the U67
Post by: aremos on January 10, 2018, 11:20:07 am
Klaus, I hope you do with the new 67 the type of examination you did with the 47Fet!
Was extremely informative & helped (aside from trying it in my studio of course) in my decision of purchasing it.
Title: Re: Neumann reissues the U67
Post by: klaus on January 10, 2018, 01:16:56 pm
You have my promise: as soon as U67 3.0 becomes available, I will do what I did with the U47fet reissue: take it apart, analyze, test it, and, most important, listen
Title: Re: Neumann reissues the U67
Post by: Jim Williams on January 11, 2018, 11:39:41 am
A line up of the parts used or changed would be informative. Resistors and caps have changed during the years.
Title: Re: Neumann reissues the U67
Post by: David Satz on January 25, 2018, 05:50:52 pm
This reissue was announced yesterday at NAMM. The price for the set (microphone, power supply, shock mount and cable in a padded carrying case) is about $7,000 US.

The "NU 67 V" power supply, which switches automatically between 110-120 VAC and 220-240 VAC operation, is said to be compatible with old as well as new U 67s, and can be bought separately for about $1,400 US. The UC 5 cable that goes from the microphone to the power supply is also available separately for about $340 US.

Some further details (and the closest close-up photo of a vacuum tube that I've ever seen) are on http://u67.neumann.com/ (http://u67.neumann.com/).

--best regards
Title: Re: Neumann reissues the U67
Post by: klaus on January 25, 2018, 07:17:29 pm
David,
You are right, the tube in the photo of the new mic is blindingly bright and almost too close for comfort. The tube's plate looks a bit like the old Tele EF86 with chrome plate, but I cannot see a logo, and doubt that Neumann would have shelled out mega bucks for NOS.

What's also curious looking at the pictures: though the mic still has the 30ļ offset connector pin configuration of the original, here, Binder connectors were used (Amphenol-Tuchel went out of business years ago) and they are not my favorite- the plastic holding the pins is not heat resistant and melts easily during soldering, plus the Binder self-cleaning contact system is primitive, compared to Tuchel's.

Binder does not make a connector with 30ļ offset pin configuration, so they modified their standard M2xx German broadcast connector by filling and covering its key channel and drilling a new one right next to it, so the connector lines up with the mic's key, putting pin #1 in line with the key, as is standard for U67.
I've seen this done by U67 owners who could not find original U67 Tuchel females, so they used broadcast Tuchels and filled the key channel with black epoxy.

Looking forward for a complete teardown of the real thing, if someone can loan me a mic for a week...


Title: Re: Neumann reissues the U67
Post by: Deuce 225 on January 25, 2018, 10:47:31 pm
Looking forward to this review when the reissues become available.
Best,
Tim Cochran

www.tracehorse.com
Title: Re: Neumann reissues the U67
Post by: AusTex64 on January 26, 2018, 08:32:17 am
The EF86 in the pictures look very new. Iíve never seen a vintage EF86 that looked like that either. Sure am curious who made the tube. Good EF86 tubes have been hard to find for a while. If a manufacturer tooled up to make that tube, would be a great resource for guitar amps and mic preamps too.
Title: Re: Neumann reissues the U67
Post by: Kai on January 27, 2018, 03:55:46 pm
As, during my long career, I never used an U67, how does its sound compare to the 1st generation of U87's?
Title: Re: Neumann reissues the U67
Post by: klaus on January 27, 2018, 04:39:44 pm
The mic does not ship for a few weeks.
Title: Re: Neumann reissues the U67
Post by: aremos on January 27, 2018, 05:43:01 pm
Someone posted this on another site stating it just might be the following:

www.hificollective.co.uk/catalog/tung-sol-gold-ef86.html

Russian Tung-Sol?
Title: Re: Neumann reissues the U67
Post by: klaus on January 27, 2018, 10:35:16 pm
Seems like it. They don't last and tend to sound opaque, compared to good NOS versions.

Title: Re: Neumann reissues the U67
Post by: David Satz on January 27, 2018, 11:10:52 pm
Kai, an important part of the progression from the U 67 to the U 87 was a change in the high-frequency compensation which the amplifier applied to the (on its own, somewhat bright-sounding) capsule. The U 67 amplifier's gain at 16 kHz is specified at 7 dB below its gain at 1 kHz, while the U 87 amplifier applied either 3 or 4 dB less high-frequency filtering, depending on which Neumann specification sheet you follow.

So even if that had been the only difference (which it wasn't), the U 87 presented a somewhat more "etched" / detailed / "hi fi" type of sound quality in all three patterns, as compared with the U 67.
Title: Re: Neumann reissues the U67
Post by: klaus on January 28, 2018, 12:21:28 am
(...) The U 67 amplifier's gain at 16 kHz is specified at 7 dB below its gain at 1 kHz(...)

That correlates to my measurements of the K67/87capsules without high frequency compensation: they are up a whopping 8-9dB @ 8kHz.

I never understood why people thought it would be an improvement of U67 or U87 mics to remove the high frequency attenuation in the processors. Bright only feels better for about ten seconds. After that, you need Advilģ.
Title: Re: Neumann reissues the U67
Post by: aremos on January 28, 2018, 09:07:41 am
Does that have anything to do with the U87's "nasal" or "boxy" sound?
Title: Re: Neumann reissues the U67
Post by: klaus on January 28, 2018, 12:33:04 pm
Not directly. The nasal sound of the U87 is a product of other aspects of frequency and gain manipulations.

Add to this that in some U87Ai models and years capsule low end can be especially tight, and the high-impedance section was more convoluted than necessary.

All of it contributes to nasality.
Title: Re: Neumann reissues the U67
Post by: Brian Campbell on January 28, 2018, 10:15:24 pm
Word from the floor at NAAM is the tube is a current production Russian EF86.
So Klaus was correct in saying Neumann would be unlikely to spend the money for NOS tubes.
I recall Oliver A. saying that the Russian tubes were ok but the ratio of unusable and/or unreliable ones was high. I'm sure that Neumann would have fairly strict QC requirements given the high profile of the U67 reissue.
Title: Re: Neumann reissues the U67
Post by: aremos on January 29, 2018, 09:23:51 am
Is this the only microphone with a power supply that Neumann makes ... and the last one with a PS they made was the U67 (1st generation & 90's reissue)?
Title: Re: Neumann reissues the U67
Post by: klaus on January 29, 2018, 12:25:30 pm
Neumann makes power supplies for M147, M149, M150. Can you rephrase your question?
Title: Re: Neumann reissues the U67
Post by: Nob Turner on January 29, 2018, 02:10:12 pm
That correlates to my measurements of the K67/87capsules without high frequency compensation: they are up a whopping 8-9dB @ 8kHz.

I never understood why people thought it would be an improvement of U67 or U87 mics to remove the high frequency attenuation in the processors. Bright only feels better for about ten seconds. After that, you need Advilģ.

I find this comment interesting, as you modified a U67 for me in the 1980's that came back significantly brighter than when it was stock. While it was great on sax and a few singers, it tended to be too bright for most applications, and after returning it to you once with a request to correct that issue, I eventually sold it.
Title: Re: Neumann reissues the U67
Post by: klaus on January 29, 2018, 02:30:30 pm
That a K67 capsule is too bright without attenuation, and that my work on your U67 ended up being too bright for your taste are unrelated. I would never release a U67 without high frequency attenuation.

In your case, it must have been my interpretation of what constitutes a reasonable amount of high frequency content in the balance. According to my records, it's been 23 years since I worked on your U67, and I apologize that I do not recall your dissatisfaction with the top end, to the point that you sold the mic.

But to hear of such outcome is extremely disappointing to me*, even after more than two decades have passed, because I pride myself of following up with my work until every client is truly satisfied with the result - one more reason I give an unconditional warranty on my work.

*It's especially disappointing, because readjusting the attenuation in a U67 is about as easy as it gets.
Title: Re: Neumann reissues the U67
Post by: J. Mike Perkins on January 31, 2018, 01:40:16 pm
If you are going to spend $7,000 to buy a new U67, spending another $150 to buy a replacement NOS tube seems like a no brainer.  While the NOS tube supply is not unlimited, thank goodness we are not talking about a VF14 or an AC701.

I can understand Neumann putting a current-production tube in the mic because they want to be consistent from mic to mic, but it's so easy to replace the tube, I don't think this is much of an issue. 

If I buy one, I would probably get 2-3 different NOS tubes to see which one I liked the best.  Assuming the U67 is an accurate reproduction, I bet you this will be a good seller for Neumann.  I hope they keep the mic in production.  Their next re-issue should be the KM84.
Title: Re: Neumann reissues the U67
Post by: aremos on January 31, 2018, 11:19:58 pm
Which are those NOS tubes you would purchase?
Title: Re: Neumann reissues the U67
Post by: soapfoot on February 02, 2018, 08:40:48 am
Which are those NOS tubes you would purchase?

I agree that it would be a trivial matter (and a no-brainer) to get a proper EF86 for this mic, and I would choose a Telefunken EF806s
Title: Re: Neumann reissues the U67
Post by: klaus on February 02, 2018, 11:53:55 am
... if you happen to like that tonality. They are certainly tops in regard to longevity and noise.
Others may choose Amperex, Dutch Phillips, still others prefer Mullards, or Valvos.

Unless I forgot one, all of the above represent the extent of NOS EF86 manufacturers. The rest is relabels.
Title: Re: Neumann reissues the U67
Post by: Nob Turner on February 03, 2018, 02:56:57 am
That a K67 capsule is too bright without attenuation, and that my work on your U67 ended up being too bright for your taste are unrelated. I would never release a U67 without high frequency attenuation.

In your case, it must have been my interpretation of what constitutes a reasonable amount of high frequency content in the balance. According to my records, it's been 23 years since I worked on your U67, and I apologize that I do not recall your dissatisfaction with the top end, to the point that you sold the mic.

But to hear of such outcome is extremely disappointing to me*, even after more than two decades have passed, because I pride myself of following up with my work until every client is truly satisfied with the result - one more reason I give an unconditional warranty on my work.

*It's especially disappointing, because readjusting the attenuation in a U67 is about as easy as it gets.

you modified my u67 in the 80's when you were living in SF. it got hotter, brighter, fuller. i loved it in those days - analog days, when everything went to tape, at least twice. as times changed and i was working in the digital medium, i found the mic too bright for most applications. eventually, i sent it to you, telling you that was my issue with it. you returned it to me saying nothing was wrong with it. that's when i started thinking about selling it, and eventually did so. i replaced it with an M49, which i find more often useful than that 67 was.
 
i happen to currently own a u87 that you modded at some point. i LOVE that mic, and in fact used it for a session yesterday afternoon. it's one of the top 2 or 3 mics in my collection in terms of actual use. so i've no issue with your mods in general. it was just that 67 that didn't warrant its financial value while barely getting used here. perhaps you misunderstood my concerns about it when i sent it. in any case, it's long gone.
Title: Re: Neumann reissues the U67
Post by: klaus on February 03, 2018, 03:29:49 am
Thanks for clarifying.
I indeed interpreted the high frequency response of condenser mics I modified hotter in the last century, to compensate for the cumulative high end loss of 24 track recording especially when two of these machines were often linked in the 1980s and 1990s to get 48 tracks.

Best,
KH
Title: Re: Neumann reissues the U67
Post by: Timtape on February 03, 2018, 04:19:36 pm
Thanks for clarifying.
I indeed interpreted the high frequency response of condenser mics I modified hotter in the last century, to compensate for the cumulative high end loss of 24 track recording especially when two of these machines were often linked in the 1980s and 1990s to get 48 tracks.

Best,
KH

When two 24 track machines were linked there was no cumulative high end loss as there was no need for dubbing from one 24 track machine to the other resulting in a second generation. It just allowed more multitracks, actually 46, not 48 as each machine had to sacrifice one of its tracks for time code.

Studio analog tape machines while not having  the fidelity of digital machines could still perform quite well if well maintained and aligned. If a machine was down in the top end, a not uncommon occurence,  you found out why and fixed it. In my view, using a microphone with artificially boosted top end, or using EQ ahead of the tape machine, would have been a strange way to address the problem of a poorly  maintained machine.   
Title: Re: Neumann reissues the U67
Post by: Kai on February 03, 2018, 05:48:47 pm
..using a microphone with artificially boosted top end, or using EQ ahead of the tape machine, would have been a strange way to address the problem of a poorly  maintained machine.
Even with perfectly aligned machines (this was the normal situation!), in the analog era boosting the treble before going to tape was very common and necessary. You either had a machine without Dolby, then you had to watch out for the signal to noise ratio, or you had the Dolby's which had negative influence on the attacks and therefore on the subjective treble dynamics.
Usually you recorded very hot, and this further compressed the treble by saturation. When I switched to digital (32 track PD-format) this was the biggest change for me, I could define the amount of treble in the mix.
Title: Re: Neumann reissues the U67
Post by: klaus on February 03, 2018, 06:41:59 pm
Agreed, I phrased that sentence poorly.

I should have said:

"Cumulative masking and other tape noise when you combined 48 individual tracks affected overall high-end and its subsequent treatment during mix-down. One way to mitigate the problem up front, (though poorly) was by boosting high frequencies in microphones".

I cannot tell you how often I was forced to boost beyond my own comfort range, just to make people happy.

P.S.: This discussion is of course WAY off the original U67 thread, but I'll leave it be. Once I have the U67 reissue in hand, I'll start a fresh thread on just that subject.
Title: Re: Neumann reissues the U67
Post by: Timtape on February 03, 2018, 09:58:09 pm
Even with perfectly aligned machines (this was the normal situation!), in the analog era boosting the treble before going to tape was very common and necessary.

Perhaps perfectly maintained and aligned machines were common in studios which could afford it and exercised due diligence but I'm not sure it was the normal situation across the board, from the big studios down to very small outfits. (I serviced tape machines for smaller outfits and often I couldnt believe how badly maintained and aligned they were).

Boosting the treble (and cutting it by the same amount on playback!) was useful in recording some instruments not strong in treble content, such as a naturally dark sounding piano. You were lifting what quiet treble sound was there in the performance above the tape noise, but without unduly driving the tape into saturation. 

You either had a machine without Dolby, then you had to watch out for the signal to noise ratio,

Of course and it depended on the programme being recorded, classical music being generally the most demanding, and on the S/N of the tape machine and tape, eg: wide or narrow tape tracks, older or newer tape formulations. And it wasnt just the treble. The dynamic range of pro machines was not brilliant across the whole spectrum, but it was much more even than say cassettes where the S/N in the treble spectrum was much worse than in its mids and bass.


 or you had the Dolby's which had negative influence on the attacks and therefore on the subjective treble dynamics.

Ray Dolby's A system, unlike the later economical Dolby B for cassettes, was a full range system, improving the S/N from the lowest bass to the highest treble. If the noise was only an issue in the treble, Dolby's job would have been a lot easier and the processors studios bought would have been a lot simpler and cheaper.

Did Dolby A mess up the treble? As far as I know, well designed and maintained Dolby A circuitry itself was essentially transparent  (easy to test this: connect the encoder's output to the decoder's input - no tape machine in circuit - and listen for any distortions) but when used with a poorly aligned/ maintained tape machine, Dolby A did exaggerate any misalignment. Even momentary tape dropout was exaggerated. All  double ended NR systems required very high standards of machine maintenance and calibration, with some more fussy than others. No surprise as they were compansion systems.

Usually you recorded very hot, and this further compressed the treble by saturation.

Recording very hot tended to compress/distort whatever portion of the spectrum was saturating,  whether bass, mid or treble, as well as caused IM distortion, which sort of defeated the purpose.

Of course greatly compounding the problem was generational losses. Particularly so in film production. Cinema audiences could be hearing a sound track 5 generations removed from the original elements.

When I switched to digital (32 track PD-format) this was the biggest change for me, I could define the amount of treble in the mix.

Yes and nearly everybody uses digital today for good reason.

Klaus mentioned people wanting mics with a large treble boost, apparently as a general fix to compensate for poor S/N in a tape machine.  I suggest these people were not well informed in that it didnt really solve the problem and was a fairly primitive technique at best.

Regards,
Tim
 
Title: Re: Neumann reissues the U67
Post by: Nob Turner on February 04, 2018, 12:14:16 am
I know, I'm responsible for this bunny trail off the original thread. Still, I'd like to repeat that everything, back in the day, went through at least 2 analog generations: multitrack and mixdown. If you were comping and/or flying parts, there were more. Each added noise and nonlinearity (the latter in the top and bottom end in particular). Yes, in theory analog machines were flat. In practice, they never were.

I also had the experience of the sound coming off tape "relaxing" after a day or so on the reel. I have no scientific evidence to support it, but I often noticed that what I'd recorded on one day typically sounded a bit "gauzier" the next. Yes, the machines were de-gaussed daily. Yes, they were aligned, maintained, etc. So, like many, I developed the habit of boosting high end on the way in, so that I'd actually have more or less what I wanted later on. Not to mention not wanting to have to boost too much top end when the tape's inherent noise had been added to the original signal.

With the advent of digital recording, I was able to expect a closer copy of what went into the recorder on the way back out. I'm not interested in arguing preferences for analog vs. digital; I'm just saying that my work just changed significantly when the medium changed. In particular, my choices of microphones were different as I adjusted.
Title: Re: Neumann reissues the U67
Post by: Timtape on February 04, 2018, 06:06:10 pm
Thinking about the loss of treble it sounds like gradual demagnetisation due to repeated shuttling the tape back and forth to do overdubs. The treble is the first thing to go. I think Roger Nichols describes this happening very badly in a Steely Dan session.
Title: Re: Neumann reissues the U67
Post by: Kai on February 04, 2018, 06:37:12 pm
I know, I'm responsible for this bunny trail off the original thread.
Don't worry, it's fun to remember the old days and it has a lot to do with how mic's were tuned at that time.

I also had the experience of the sound coming off tape "relaxing" after a day or so on the reel. I have no scientific evidence to support it, but I often noticed that what I'd recorded on one day typically sounded a bit "gauzier" the next.
It's not from one day to another, but the tape beeing played multiple times during overdub an mix degraded the sound. Something I noticed very often.
This negative effect was enhanced by the Dolby systems.
As I did my machine maintainance by myself I ended up precompensating this by adjusting the machine's treble a tiny bit on the bright side (+1dB@12kHz) and the level very slightly on the plus side too.
This even compensated for tape saturation effects and made the Dolby act subjectively more linear.

IM distortion BTW wasn't that much of a problem, as the split into a multitude of channels prevented much of the frequencies interaction.
What was left was the dynamic harmonic enrichment and the "limiting" effect of tape saturation, being positive or negative depending on the source.

Finally, in the context of microphones, the today so famous great oldies were build to work best with these systems, long before digital recording.
Title: Re: Neumann reissues the U67
Post by: Timtape on February 04, 2018, 07:20:45 pm
Is there any documented evidence from the microphone manufacturers themselves that they designed mics with built in treble boost to compensate for tape demagnetisation? I've never read anything like that.

It always made sense to me to compensate for a tape machine problem at the tape machine. Kai mentions setting up a tape machine with slightly bright treble to anticipate mild demagnetisation. There's good support for that practice in some  tape machine service manuals where a specification for  10kHz re 1kHz would have a tolerance of say (0 to +1db), especially when Dolby NR was engaged.
Title: Re: Neumann reissues the U67
Post by: Kai on February 05, 2018, 04:18:57 am
Is there any documented evidence from the microphone manufacturers themselves that they designed mics with built in treble boost to compensate for tape demagnetisation? I've never read anything like that.
Of course not, but everything sounded a bit softer in those days; remember the all-tube preamps and mixers we had.

Then came germanium electronics, still soft; silicone, with the tendency into harsh, mainly because engineers did not know how to use it; soon after that the first generation of operational amplifiers (the 741), very slow and therefore dull and distorted sounding.

Not to mention the media with which the music was delivered to the customer: vinyl, compact- and 8-track cassettes, all with their own sound.

And then, from this deep valley of really bad sound the quality emerged into what we have today.
All this had influence on the way microphones were built and tuned, as it was and is the end result that counts.
Title: Re: Neumann reissues the U67
Post by: Jim Williams on February 05, 2018, 11:18:51 am
Tape sound was a lot better than some recall. Not everything was a mush machine. Back in the 1980's high test analog machines were used. In 1980 Stevie Wonder got one of the first digital 3M machines. "Hotter Than July" was recorded on it with an API console (another mush machine).

I routinely rebuilt analog machines in the LA area back then. Some would drop THD levels from the stock .55% at +3 down to .15% at +9. The frequency response on some 1/2" mastering decks would reach 32k hz. Back then the decision was to either use the DAT mix or the 1/2" at 30 IPS. The 30 IPS won every time.
Title: Re: Neumann reissues the U67
Post by: Timtape on February 06, 2018, 09:04:45 am
...All this had influence on the way microphones were built and tuned, as it was and is the end result that counts.

Again do you have any evidence for that?
Title: Re: Neumann reissues the U67
Post by: klaus on February 06, 2018, 04:04:34 pm
There is a place for evidence-based discussions in audio forums, but you seem to over-reach with your repeated requests for iron-clad, objective outcomes in a field that does not easily produce the type of scientific proof you want.

May I remind you that observation and sensual impressions are also part of scientific exploration? Your education about microphones may indeed benefit from observing the deep level of experience veterans in our field share here.

No one stops you from venturing on your own into examinations and the type of scientific inquiry you have in mind, and I'd love it if you would share those with us.
Title: Re: Neumann reissues the U67
Post by: Kai on February 07, 2018, 09:04:27 am
Again do you have any evidence for that?
Yes, I have as I have been involved in audio developments of all kinds for a long time. It's always an interaction between trying out something, listen to it, measure it, test it in the real world and with your potential customers and then change it until everyone involved is satisfied.
This does not mean I have insight how Neumann developed their microphones in 1950, because I was not born at that time, but I guess it wasn't much different.
I bet that they did a lot of listening and other practical evaluations (including recording), because the possibility for measurements was much more limited, and they had years of development for every model, and a high commercial pressure doing it right.
Title: Re: Neumann reissues the U67
Post by: Timtape on February 07, 2018, 10:58:55 am
Sure that sounds fine but in the previous post you seemed to suggest mic manufacturers changed the design or performance of their studio mics on the basis of the active electronic components of the day in amps and pre's  like tubes, germanium or silicon transistors etc. Or on the basis of whether the music recordings were released on vinyl, cassette or 8 track etc.
It's true mastering engineers took  care to optimise  the recorded signal as it was  cut for vinyl, and perhaps to a lesser extent for cassette and 8 track.
It's also true that at mixing stage, staff listened to mixes on smaller low fidelity speakers like Auratones to help gauge if a mix still sounded reasonable on limited fidelity consumer systems.
But the idea that studio microphone parameters were altered on the basis of such factors further downstream of the recording, or even downstream of the microphone is something I dont remember ever encountering before.

Regards
Tim
Title: Re: Neumann reissues the U67
Post by: Kai on February 07, 2018, 02:51:28 pm
But the idea that studio microphone parameters were altered on the basis of such factors further downstream of the recording, or even downstream of the microphone is something I dont remember ever encountering before.
Think of the sound change from Neumann's M7 capsule to its successor, the K47, and correlate it with the sound evolution of the typical audio chain of the regarding time. I can see some coincidence.

Do you think this difference happened just by chance or wouldn't an advanced company like Neumann have done this on purpose?

I admit I'm fishing in muddy waters, but... nothing comes from nothing they say.
You can even turn that around -  if the sound of a microphone wouldn't have fit to the contemporary taste and circumstances it would not have been a commercial success and we would not know about it today.

If we look further we can see, with the appearance of high samplerate recording systems, microphone manufacturers started to build microphones with defined frequency responses beyond 20 kHz, e.g. if you go to the Schoeps website the "Schoeps CMC 6xt U".
Title: Re: Neumann reissues the U67
Post by: Timtape on February 08, 2018, 02:04:46 pm
I'm sorry Kai but I am struggling to understand what you are talking about here. I'm not sure what more to say.

Best wishes
Tim
Title: Re: Neumann reissues the U67
Post by: klaus on February 08, 2018, 04:00:41 pm
I understood Kai's post as making two points:

1. We don't know whether the parallel evolution of microphones and recording technology through time was intentional or coincidental.

2. Regardless, mic manufacturers who did not adapt the sound of their mics to changes in recording technology went under or lost sales, whereas those who did, thrived, or had a better chance to survive.
Title: Re: Neumann reissues the U67
Post by: Timtape on February 09, 2018, 03:33:30 am

If we look further we can see, with the appearance of high samplerate recording systems, microphone manufacturers started to build microphones with defined frequency responses beyond 20 kHz, e.g. if you go to the Schoeps website the "Schoeps CMC 6xt U".

Just  commenting on this one point. I believe mics capable of above 20kHz response have been around a long time. B & K have been making measurement mics with diaphragms down to 1/8" diameter for this purpose. I think such mics were around since the 70's for industrial measurement purposes. So I dont think this came about because of higher sample rate recorders, or just because of them.

I believe these days most recording studios either do, or have the capability these days to, record at 96kHz or higher sample rate but I'm not so sure many insist on using mics with defined responses above 20kHz.


 
Title: Re: Neumann reissues the U67
Post by: David Satz on February 09, 2018, 11:46:16 am
Schoeps often receives requests for special versions of their microphones. They're a small company, and they give serious consideration to such requests. The CMC 6 xt exists because a customer requested a CMC 6 amplifier with response to 40 kHz and was willing to place a definite order for a batch of them at extra cost. Schoeps then asked around and found some other customers who were interested in this type of amplifier. So they not only produced the initial batch, but added it to their catalog, placing it along with other amplifier variants that they already offered. For example, amplifiers could optionally have their built-in low-cut filter set for a frequency below 20 Hz, and/or have +5 dB gain instead of unity; special engraving and surface finishes, etc. may also be ordered.

This implies no endorsement by Schoeps of any theory other than "it can be good business to give your customers what they ask for." The company caters to a perfectionist clientele, and if they believed that 40 kHz response gave audibly superior results--or maybe even if they thought that their customers by and large believed it--you'd expect them to make the "xt" their standard model, or a prestige/flagship model. Instead it is simply presented as an alternative for those who want it, along with other special versions.

--best regards

P.S.: Sennheiser is a different case; their chief of microphone design (Dr. Manfred Hibbing) is on the record with several statements about high sampling rates and extended high-frequency response for microphones. If Klaus feels that this isn't too far off-topic already, I could post some of what he's said in interviews and written in an AES paper about it. But I must say that I find some of his statements problematic.
Title: Re: Neumann reissues the U67
Post by: boz6906 on February 14, 2018, 11:38:27 am
I, for one, would like to hear more about the rational for higher freq. response mics, above 20kHz.

I've read of experiments showing positive benefits but many of the test methods seemed imprecise.

Title: Re: Neumann reissues the U67
Post by: klaus on February 14, 2018, 12:50:51 pm
I've read of experiments showing positive benefits but many of the test methods seemed imprecise.

Even without knowing the methodology of these experiments, I would be surprised if anything conclusive or "precise" resulted. Personal, inherently subjective, interpretation of sound continues to be the guideline for our preferences.

(Unless you call the original experiment how we ended up with the definition of one decibel "precise"...)
Title: Re: Neumann reissues the U67
Post by: richbreen on February 15, 2018, 12:43:08 pm
I, for one, would like to hear more about the rational for higher freq. response mics, above 20kHz.

I've read of experiments showing positive benefits but many of the test methods seemed imprecise.

Talk to film SFX editors/designers who need to move recordings down several octaves while maintaining fidelity, and without moving aliasing artifacts into the audible band.
Title: Re: Neumann reissues the U67
Post by: boz6906 on February 17, 2018, 11:36:10 am
Very good, your point is well taken.

If one needs to manipulate a sample by lowering the pitch, having the f/s very high would keep the artifacts above audibility.  I've encounter that very problem; needing a nice explosion I lowered the pitch of a gun shot... then had to high-pass to remove weird rattily sound...

So clearly there is a need to record at higher f/s for many professionals.  But does it lead to a better musical experience for a straight acoustic recording?

I have seen research using same music sample as A, with B sent through 20kHz low pass.  Subjects picked A, the unfiltered sample.

But the tester provided no info on the filter topology, it could have easily been the problem.
Title: Re: Neumann reissues the U67
Post by: rmburrow on February 17, 2018, 06:55:43 pm
As, during my long career, I never used an U67, how does its sound compare to the 1st generation of U87's?

If the new U67's duplicate the original, you will leave your U87's in the locker when you hear the U67.  I've used U67's on classical ensembles, the "warm" tube sound is apparent.

Use a wind screen at all times for vocals.  I don't use my condenser mics on vocal, period.  Protect the capsule; big money to replace.  I assume the WS67 wind screen is extra.

As for the tube, the JJ Electronik EF806s has a dark anode.  Would be interesting to know the manufacturer of the EF86 used in the reissue.

Neumann was smart to start building tube mics again.  Hopefully the new U67's sell since buyers will get a new proven mic with a warranty.

Title: Re: Neumann reissues the U67
Post by: klaus on February 17, 2018, 10:40:32 pm
Use a wind screen at all times for vocals.

Maybe not at all times, but when it's windy or when extreme circumstances call for extra capsule protection.

The WS87 lops off high frequency and transparency of sound. Besides, with time, it sheds foam which must not be allowed to settle on the capsule's surface.

The better idea for vocals: a stocking screen with a double layer of nylon hose as spit barrier.
Title: Re: Neumann reissues the U67
Post by: aremos on April 13, 2018, 09:45:22 am
Received the U67 reissue and after 1 hour of recording the mic started with a hum & no signal coming in!
Turned it off for 1/2 hour then turned it back on & has been working so far.
Any thoughts?

Called Sennheiser & they wanted me to trouble shoot my power source, power cable, preamp, etc. Told them that that protocol has been used by other mics, etc. Their response was to send the mic in - if I wanted to.

BTW, Mic sounds very nice.
Title: Re: Neumann reissues the U67
Post by: klaus on April 13, 2018, 01:08:10 pm
It may be the newly designed power supply, but that is mere speculation. If you have another U67 supply, you could, on a temporary basis, plug your new U67 and observe the result.

You could also do the reverse test: plug another (original) U67 into the new cable + power supply.
Title: Re: Neumann reissues the U67
Post by: aremos on April 13, 2018, 03:35:44 pm
Thanks Klaus.
Unfortunately I don't have either an extra PS or 67.
But my dealer is taking care of it already.
Title: Re: Neumann reissues the U67
Post by: klaus on April 13, 2018, 03:40:15 pm
Please report back if you find out what the problem's cause was.
Title: Re: Neumann reissues the U67
Post by: aremos on May 22, 2018, 06:53:50 pm
I just received my second U67 reissue & the EXACT same thing as the first one (received 13 APR) happened!:
After 1+ hours of recording the mic started with a hum & no signal coming in! Turned it off for 1/2 hour then turned it back on & has been working so far.
The first one has been working fine since that happened.

Has anyone else had this problem?
Title: Re: Neumann reissues the U67
Post by: Kai on May 23, 2018, 12:53:52 pm
Now you have 2 power supplies and can switch to find out if the problem follows the microphone or the PSU -  if the problem reappears at all.
Does this problem show up when you plug the PSU into a certain wall outlet or use a certain power cable?
Title: Re: Neumann reissues the U67
Post by: aremos on May 23, 2018, 01:43:08 pm
Now you have 2 power supplies and can switch to find out if the problem follows the microphone or the PSU -  if the problem reappears at all.
Does this problem show up when you plug the PSU into a certain wall outlet or use a certain power cable?

The same issue occurred one month apart, in the exact same way, with completely different units!
It's as if both mics (along with a different PS, different mic cable, different PS cable) had to go through some type of "settling in"?
All of a sudden, after powering up for the first time & 1.5-2 hours of working perfectly & sounding fine, the same hum started emitting & no signal being able to be recorded. After shut-off (1/2 hour) & then powering up again the mics have been working fine.

The odds of this happening only to me must be astronomical, unless it's something common. Hence why am asking & very curious if it's happened to anyone else.
Title: Re: Neumann reissues the U67
Post by: klaus on May 23, 2018, 01:58:30 pm
When I will review the mic (as soon as VK has a spare to send me), I will look at this issue.

My suspicion: it's the same issue I had once with an M150 power supply of similar construction: A Chinese-made AC-DC converter is embedded in the supply, similar to what a wall wart does, and it shut down (a type of circuit breaker senses overheating or other maladies) until it recovered. I replaced the converter (a third-party item that can be found on eBay) and the problem never reoccured.

Have you checked the AC at the plug where you connect the power supply?
Title: Re: Neumann reissues the U67
Post by: aremos on May 23, 2018, 05:18:47 pm
...
Have you checked the AC at the plug where you connect the power supply?

Yes. Haven't had any problem with anything else plugged into it (including a C-800G & REDD mics).
Title: Re: Neumann reissues the U67
Post by: klaus on May 24, 2018, 03:11:05 am
I meant the voltage coming out of the wall.
Title: Re: Neumann reissues the U67
Post by: brucekaphan on June 29, 2018, 06:33:21 pm
Is Klaus' U67 reissue review still forthcoming, or has he done it already and somehow I missed it?
Title: Re: Neumann reissues the U67
Post by: klaus on June 29, 2018, 07:15:59 pm
Bruce,
It's forthcoming, in about a week. Lots of surprises, too!
Title: Re: Neumann reissues the U67
Post by: brucekaphan on June 30, 2018, 06:40:27 am
Thanks, Klaus! Excellent news!
Title: Re: Neumann reissues the U67
Post by: RuudNL on June 30, 2018, 08:51:53 am
Looking forward to read about the "surprises"!
Title: Re: Neumann reissues the U67
Post by: ratite on July 07, 2018, 07:56:15 am
C'mon Klaus out with it!
Title: Re: Neumann reissues the U67
Post by: aremos on July 09, 2018, 11:37:39 am
C'mon Klaus out with it!

Klaus,
Please take your time. As we'd want something well done - meticulous & thorough.
Title: Re: Neumann reissues the U67
Post by: klaus on July 09, 2018, 03:20:31 pm
Writing, writing, writing...
Title: Re: Neumann reissues the U67
Post by: aremos on July 10, 2018, 10:32:30 am
In the vox of Gomer Pyle:

"Surprise, surprise, surprise" ... with pictures?
Title: Re: Neumann reissues the U67
Post by: klaus on July 10, 2018, 01:24:49 pm
Of course, with close-ups!
Title: Re: Neumann reissues the U67
Post by: Deuce 225 on July 24, 2018, 06:59:38 pm
Our U67 originally came from Belgium and the transformer is strapped for 200 ohms.  My understanding is that provides 6db more output. I am looking forward to reading Klaus's upcoming review.

Tim Cochran

www.tracehorse.com
Title: Re: Neumann reissues the U67
Post by: RuudNL on July 27, 2018, 03:53:35 am
U67 reissue: to buy, or not to buy, that's the question!
(I hope to know more after reading the review.)
Title: Re: Neumann reissues the U67
Post by: aremos on July 27, 2018, 09:58:17 am
Of course we're all looking for Klaus's review! But have been using it for months now & it's really a great mic, to say the least & in it's own right. Is it exactly & a replica of V.1 (or 2)? We'll wait for Klaus on that aspect of it.
Title: Re: Neumann reissues the U67
Post by: aremos on August 09, 2018, 11:34:14 am
Klaus,
You stated: " ... a brand-new K870 (build date late 2012), and my jaw dropped: Both sides of the capsule are lush ... 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 ... I am hoping and praying that this is a trend, and will report what the next new K870 capsule portends."

I guess that the hope of it becoming a trend didn't live up - after reading your review of the U67 Reissue?
Title: Re: Neumann reissues the U67
Post by: klaus on August 09, 2018, 11:37:12 am
Ernie Black, PSW's Webmaster Extraordinaire, is currently formatting my review for this forum. It should be up and live soon!
Title: Re: Neumann reissues the U67
Post by: RuudNL on August 10, 2018, 02:55:11 pm
Very interesting review! So again, the tensioning of the capsule membranes is the biggest problem.
Could you unveil a little how it is possible to relax the tensioning of the membranes?
(Not that I am even thinking about doing this myself!!!)
As far as I remember, the membranes were glued to the tensioning rings.
(Anyway, that is what I saw when I took a damaged Neumann U87 capsule apart.)
Title: Re: Neumann reissues the U67
Post by: klaus on August 10, 2018, 03:28:58 pm
The membranes on large diaphragm, Neumann capsules are not glued, but held in place through clamping tension.

I cannot share how I relax the diaphragms, except I am working on a device that makes my previous efforts more predictable and easier to repeat and to dial in more precisely.
Title: Re: Neumann reissues the U67
Post by: RuudNL on August 11, 2018, 06:40:51 am
Interesting. I remember I once removed the 'good' membrane from a damaged U87 capsule and used it to repair another U87 capsule. In this case, the membrane was definitely glued to the tensioning ring. (Otherwise I would never have been able to reuse it again!) The repaired microphone sounded good after this 'transplantation'.
Anyway: the owner of the microphone was very happy with the result.
Although the capsule looked as an original Neumann one, there is of course a chance that it had been replaced with a third party one. Or could it be that after many years of use the membrane just sticks to the tensioning ring? (I would be surprised if this happens.)
Title: Re: Neumann reissues the U67
Post by: mikezietsman on August 11, 2018, 07:39:01 am
It is quite easy to unscrew the two halves of a k87/k870 capsule but if you touch even a single screw that is holding the diaphragm in place, you will ruin the tension in the diaphram.

Source: I took apart a diaphragm that had been ruined by an amateur cleaning attempt.

I can say with a certain authority that these diaphragms are both tougher and more fragile than most people realise. I imagine it is a thing of working with them a lot that helps you to understand in which ways they are tough and in which ways they are fragile.

I experimented on two completely ruined diaphragms... Had I experimented on a two working diaphragms, I would have ended up with two non-working diaphragms...

Interesting. I remember I once removed the 'good' membrane from a damaged U87 capsule and used it to repair another U87 capsule. In this case, the membrane was definitely glued to the tensioning ring. (Otherwise I would never have been able to reuse it again!) The repaired microphone sounded good after this 'transplantation'.
Anyway: the owner of the microphone was very happy with the result.
Although the capsule looked as an original Neumann one, there is of course a chance that it had been replaced with a third party one. Or could it be that after many years of use the membrane just sticks to the tensioning ring? (I would be surprised if this happens.)
Title: Re: Neumann reissues the U67
Post by: RuudNL on August 11, 2018, 08:30:27 am
Yes, I have seen many capsules that were destroyed by people who had attempted to 'clean' the membranes!
Gold wiped off, holes in the membranes etc.
Once I got a capsule that was cleaned so thorougly, that all the gold was gone...
The owner asked if I didn't have a spraycan, so I could apply a new layer of gold.  :D
I explained to him that it didn't work this way...
Title: Re: Neumann reissues the U67
Post by: gtoledo3 on August 12, 2018, 02:49:15 pm
Very interesting review! So again, the tensioning of the capsule membranes is the biggest problem.
Could you unveil a little how it is possible to relax the tensioning of the membranes?
(Not that I am even thinking about doing this myself!!!)
As far as I remember, the membranes were glued to the tensioning rings.
(Anyway, that is what I saw when I took a damaged Neumann U87 capsule apart.)

Heat could possibly decrease Mylar tension, but the problem in this case that is that it has gold bonded to it.

Any sort of pre-age/stress like heat would be best done before application of the gold, because with heating after the fact the gold and Mylar will not respond in the same way to heat, which may theoretically cause abberations in the bond, at least according to research.

That said, itís hard to think of other approaches to tweak the tension of an assembled capsule.
Title: Re: Neumann reissues the U67
Post by: gtoledo3 on August 12, 2018, 02:53:03 pm
Klaus, did you consider variability of the caps for the high frequency shunts as another thing to examine in differences of new vs vintage? (Not naysaying your point about the tension!)

It was occurring to me that what happens with the top end there, can also really pop out to the ear.
Title: Re: Neumann reissues the U67
Post by: klaus on August 13, 2018, 10:57:22 am
Heat could possibly decrease Mylar tension, but the problem in this case that is that it has gold bonded to it.
Heat does the opposite to Mylar: it tightens it. That's why drum shops apply heat to dented Mylar heads; the dents come out that way.
Title: Re: Neumann reissues the U67
Post by: gtoledo3 on August 13, 2018, 02:33:24 pm
When you have a drum head under tension and heat it, a dimple stretches and the Mylar thins. You can then tighten the drum head up more, heat again. Rinse and repeat. Until the drum head gets so thin that itís shot or breaks.

I thought the pitch relaxed when it thins out on the head, with it being under tension. But it goes up more like shrink wrap? Interesting. I have some timbale heads here that Iíll do that to soon, and pay close attention.
Title: Re: Neumann reissues the U67
Post by: Kai on August 14, 2018, 06:22:28 pm
Heat could possibly decrease Mylar tension ...
Mylar is pre-tensioned or stetched during manufacturing. Depending on the tension used in the capsule it's more likely that heat will increase the tensioning.
But - we do not know how Neumann treats the mylar in the manufacturing process.
Title: Re: Neumann reissues the U67
Post by: gtoledo3 on August 16, 2018, 11:10:50 pm
Mylar is pre-tensioned or stetched during manufacturing. Depending on the tension used in the capsule it's more likely that heat will increase the tensioning.
But - we do not know how Neumann treats the mylar in the manufacturing process.

More than you ever wanted to know about Mylar:

http://usa.dupontteijinfilms.com/wp-content/uploads/2017/01/Mylar_Physical_Properties.pdf

The long story short is that it appears that tensile strength goes down with heat increases and elongation goes UP. At extremes it finally becomes brittle.

Mylar can be preheated, which will serve to condition it, but up to that heating point, not above. I also read another abstract about UV exposure pretreatment fwiw.

I still havenít done the test on the timbales :-) Recovering from a slip and fall, which probably accounts for more than half of the time I spent chattering about this. (Sorry Klaus!)
Title: Re: Neumann reissues the U67
Post by: klaus on August 17, 2018, 01:22:21 pm
Figures 3 and 4 of your linked article shows increasing shrinkage of Mylar with increased heat, in all cases. What am I not getting here about your counter argument?

Besides, I've tested this with Mylarģ capsules repeatedly: resonance frequency goes up with heat applied to the tensioned diaphragms.

Get well soon!
KH
Title: Re: Neumann reissues the U67
Post by: aremos on December 03, 2018, 07:27:19 pm
Hi Klaus,
Wanted to know if these look like the Amperex tubes you talk about?
Title: Re: Neumann reissues the U67
Post by: klaus on December 03, 2018, 08:27:11 pm
Yes.
But keep in mind what I try to emphasize any time we talk about tubes for microphones, even the very best:
Test each tube individually in the mic the tube is intended for and leave it on for at least 48hrs straight-

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