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Author Topic: Clean, reskin or replace a capsule?  (Read 5278 times)

Yogi

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Clean, reskin or replace a capsule?
« on: April 30, 2005, 04:09:55 pm »

I have searched this forum and others as well but what I found has just confused me more.
Some microphone gurus say 'if it's dirty, have it cleaned'. Others say 'it doesn't worth cleaning, it will be the same in a few months. If it's dirty have it reskinned.' The first group replies  'do not reskin it, you better replace the whole capsule'.
Now who's right? All of them are real experts; the capsule is a K87.
Any thoughts will be much appreciated.

Yogi

Kert
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David Satz

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Re: Clean, reskin or replace a capsule?
« Reply #1 on: April 30, 2005, 05:32:02 pm »

Yogi, ordinary dust or dirt which simply sits passively on a capsule surface is not usually a problem. But if you breathe gently and warmly onto the diaphragms so that a little moisture condenses on them, and if this causes the audio to cut out for a few seconds or loud noises to occur, then there are two things to consider: [a] An experienced microphone repair person should probably try to clean the capsule, and if the cleaning succeeds, Whoever has been using the microphone should immediately begin to use a wind screen or pop screen whenever it (or any other condenser microphone) is being used for close-up vocals.

"Reskinning" a capsule should be considered only if the original capsule type is no longer available, since the results are somewhat unpredictable. Genuine Neumann capsules for all models of U 87 are readily available. They are expensive, however, so please review item above.

--best regards
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volki

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Re: Clean, reskin or replace a capsule?
« Reply #2 on: May 01, 2005, 03:39:27 am »

I might add two thoughts about reskinning:

1. Usually, reskinning will be cheaper than getting a new capsule. On the other hand, it's more tricky, and the tech should really know his stuff. It requires individual tuning of the diaphragm so as to get within the limits of tolerance for the required frequency response. If an original diaphragm is used, a good tech should be able to do that. If the diaphragm is non-original and thus might have different properties, I'm not sure (Klaus?).

2. It has already been debated on this forum if re-skinning with a non-original diaphragm generally alters the sound, and if so, for better or worse. Obviously, there doesn't seem to be a general answer to this one, but it seems to get more important when differences of materials are involved. As for the frequently quoted example of the Neumann M7 capsule, which originally has a PVC diaphragm (hard to come by as a spare part), there obviously are differences if fitted with a (readily available) PE ("Mylar") diaphragm as in the successor KK47. The KK87 originally has a PE diaphragm, though, so only point #1 should be relevant here.
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Volker Meitz

Klaus Heyne

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Re: Clean, reskin or replace a capsule?
« Reply #3 on: May 01, 2005, 09:24:01 pm »

Yogi wrote on Sat, 30 April 2005 13:09


Some microphone gurus say...'it doesn't worth cleaning, it will be the same in a few months. If it's dirty have it reskinned.' ...
the capsule is a K87.



There is an ironclad policy here to insist on attribution anytime you quote someone. You did not provide the source(s) for the above quote.

Please do so, because, as cited above, I have a hard time believing that anyone familiar with condenser mic capsules would say such thing.

As David Satz points out, capsule cleaning and -preservation is a fundamental maintenance task for any mic owner. (See also my Sticky at the head of the forum titled "How to keep a condenser capsule clean and dry.")

So why would anyone say it's not worth cleaning (or, by extension, preserving) a capsule, but one should replace the diaphragm (again, what? every time it's dirty?)

Beyond that, It can be debated whether replacing original diaphragms with aftermarket parts has sonic merits over capsule replacement from the original manufacturer (where still available)
But  I do not believe that any serious microphone specialist would disagree with my contention that an after market diaphragm that is mounted on an original backplate will ever sound like the original capsule sounded, just like any aftermarket capsule ever sounds like the original it tries to emulate.

Kind regards,
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Klaus Heyne
German Masterworks
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Yogi

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Re: Clean, reskin or replace a capsule?
« Reply #4 on: May 02, 2005, 02:21:28 am »

Forgive me, Klaus, I understand that your mic lab is not like other forums so here are the details:
You wrote me on 08 Feb:
Try Neumann, Berlin first. If they cannot do some of the mics, try Andreas Grosser, Berlin.
Of course I tried Neumann first. This is what Marlies Stern (service department) replied:
We are assured that it will be not possible to refurbish capsules which are older than 10 years.
I tried Andreas Grosser. He replied:
i dont clean capsules
after cleaning the K87 capsule you have a quarter year later the same problem

He recommended Siegfried Thiersch. His reply:
I don't clean K87 capsules. It isn't worthwhile. I only reskin capsules.
Both Mr Grosser and Mr Thiersch are well known microphone repair persons with well deserved reputation. They are recommended not only here but at Neumann's pinboard as well.
I must mention that the question was not about keeping a capsule clean. I read your sticky and other articles on this before but these microphones are already dirty so I have to have them cleaned first. (QM 69 was glued into the plastic foam it was  kept in...)
And yes, replacing the diaphragm instead of cleaning it doesn't make any sense to me but I'm not an expert - that's why I asked.

Best

Kert
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Klaus Heyne

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Re: Clean, reskin or replace a capsule?
« Reply #5 on: May 02, 2005, 03:06:59 pm »

Yogi wrote on Sun, 01 May 2005 23:21

Forgive me, Klaus, I understand that your mic lab is not like other forums so here are the details:
You wrote me on 08 Feb:
Try Neumann, Berlin first. If they cannot do some of the mics, try Andreas Grosser, Berlin.
Of course I tried Neumann first. This is what Marlies Stern (service department) replied:
We are assured that it will be not possible to refurbish capsules which are older than 10 years.

Neumann does not "refurbish" capsules. Period. They replace them. Always.
Quote:

I tried Andreas Grosser. He replied:
i dont clean capsules
after cleaning the K87 capsule you have a quarter year later the same problem


He obviously did not recommend to solve the problem of a dirty capsule by throwing the diaphragm out and replacing it with an aftermarket product.

Quote:

 Siegfried Thiersch(s) ... reply:
I don't clean K87 capsules. It isn't worthwhile. I only reskin capsules.

Here you are right and Thiersch is wrong (or self-serving)

Quote:


...I read your sticky and other articles on this before but these microphones are already dirty so I have to have them cleaned first.
And yes, replacing the diaphragm instead of cleaning it doesn't make any sense to me but I'm not an expert - that's why I asked.



Good. I am glad we cleared it up.
I am sorry if I overreacted. Sometimes gross stupidity (not yours here, but that of the advice you received) sets me off.  

And throwing out a perfectly restorable, often irreplaceable capsule diaphragm when there is no genuine sonic substitute available would be pretty foolish.

Kind regards,
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Klaus Heyne
German Masterworks
www.GermanMasterworks.com

Karl Winkler

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Re: Clean, reskin or replace a capsule?
« Reply #6 on: May 02, 2005, 03:28:11 pm »

First let me say that my level of expertise on the subject of microphone restoration is nowhere near that of many others on this board, including of course Klaus.

That being said, I'd like to point that that in my limited experience, there are a number of factors that contribute to whether or not a capsule can be cleaned.

First, What kind of dirt is it? Some things, such as dust and saliva, will come off fairly readily with distilled water and a practiced hand. Other substances don't come off so easily.

Second, has the capsule been cleaned before? If so, how carefully was the job done? I've seen capsules that were 20 years old that had been cleaned several times and showed signs of wear - i.e. the gold deposit was worn or flaking, etc. In these cases, cleaning may damage them further or not be possible at all.

The statement that "why bother cleaning it, it will be the same in 3 months" seems quite far off, to me. If you are using your microphones in a dust-free environment (is there such a thing? <g>) and with a pop screen, etc. then you may go for several years without needing a cleaning.

One thing that I've seen done is to simply turn the capsule around, so that the side not normally facing the singer is now the front. Usually this side of the capsule is far less dirty, and since most people rely on the cardioid pickup pattern for 90% of their work, this method is viable.

The bottom line, I think, is that most often capsules can be cleaned with a minimum of fuss. This is depending of course on the above issues.

Regards,

-Karl

John Monforte

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Re: Clean, reskin or replace a capsule?
« Reply #7 on: May 03, 2005, 01:07:28 am »

It seemed apropos to note here an experience I just had.

I have been working on some old mics, including two U87's that needed repairs. One U87 was filthy and responded well to cleaning, but I noticed that even still, this one was sputtering occasionally and was still not the best example of the U87 sound.

Now, if you work in a lot of studios, you hear examples of U87s that are "working" yet there is still a wide variation in sonic character out there. Certainly it is wider than new mics, but I have not worked with enough brand new U87s to be sure that there is no variation among the factory delivered capsules. Nevertheless, there is a range of sonic character that I have become accustomed to expect in a functional U87. And even on a replacement capsule I always pick the better sounding diaphragm to face the front.

My client wanted this microphone so much as to agree to spend the amount required for a new capsule - although he could have bought a used U87 for that kind of money.

The capsule that Neumannn/Sennheiser provided was the the finest example of a K87 that I have heard so far! Period. The front and back measured and sounded IDENTICAL - to the point that I thought I had made some sort of mistake in my testing. And both sounded superb. My only theories as to why that is are:

1- Neumann has figured out how ways to make them better than ever (after all they have been making this part continuously for fifty years, they must have learned something).

2- They save the best capsules for spares, so the old fossils get revived to premium quality and thus contribute to the legend of Neumann's quality.

3- I got lucky.

I don't process the sort of volume Klaus does, so he may have a better idea which might be true or if a combination of those factors are in play. Karl would know if #2 has any validity. Nevertheless, I would not hesitate to go to the factory for a replacement part. I have never received a substandard part from Neumann - and that includes Sennheiser/Neumann. I wish I could say that about other "classic" brands, some of whom are also under new management.

Of course, if cleaning does the job, then do it. If not, get the real part from Neumann. I have had experience with good re-skinning and it falls in the range of "good", but spending the $$$ (or $$$$) to buy a Neumann part has never dissapointed me.


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Yogi

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Re: Clean, reskin or replace a capsule?
« Reply #8 on: May 03, 2005, 02:54:18 am »

Summary:
If it's not too dirty and sounds good, leave it alone.
If it's too dirty and doesn't pass the breath test have it cleaned by a real expert.
If it's damaged replace it with original Neumann part only.
Thank you guys for your help.

Kert
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Karl Winkler

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Re: Clean, reskin or replace a capsule?
« Reply #9 on: May 03, 2005, 11:28:03 am »

John Monforte wrote on Tue, 03 May 2005 06:07

My only theories as to why that is are:

1- Neumann has figured out how ways to make them better than ever (after all they have been making this part continuously for fifty years, they must have learned something).

2- They save the best capsules for spares, so the old fossils get revived to premium quality and thus contribute to the legend of Neumann's quality.

3- I got lucky.

Karl would know if #2 has any validity.


Not that I'm aware.

One change I do know about is that a few years ago (2001?) a new wing of the Sennheiser factory in Wedemark was comissioned, and includes a much larger clean room area for capsule building. All of the Neumann capsules are built in this area, thus lending credence to your #1 guess. Although there have been people, including Stephen Paul, that have decried the changes in construction methods and materials over the years, I've generally heard from customers that Neumann's replacement capsules are very very good and will usually restore the older microphones to near-new operating condition. This is of course excepting where tubes are involved unless the tubes themselves are also in top condition.

-Karl

Klaus Heyne

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Re: Clean, reskin or replace a capsule?
« Reply #10 on: May 06, 2005, 04:25:00 pm »

John Monforte wrote on Mon, 02 May 2005 22:07


The capsule that Neumann/Sennheiser provided was the the finest example of a K87 that I have heard so far! Period. The front and back measured and sounded IDENTICAL - And both sounded superb. My only theories as to why that is are:

1- Neumann has figured out how ways to make them better than ever (after all they have been making this part continuously for fifty years, they must have learned something).

No. The crucial, sound shaping aspect of manufacturing, specifically of the steps that result in a capsule's 'personality', has remained the same for the last half century.

Quote:

2- They save the best capsules for spares, so the old fossils get revived to premium quality and thus contribute to the legend of Neumann's quality.

No. Would be more lucrative to do the opposite: taint the old to sell more of the new.
Either way, the Germans don't do manufacturing business that way anyway (at least not yet)

Quote:

3- I got lucky.

Yes.
Selection for sonic consistency, side to side, of a condenser capsule is beyond a manufacturer's capabilities, aside from output matching at one specific frequency (usually 1khz)

Once in a while there are indeed two sides of a capsule that are almost identical in sound. And I am still not so sure whether that's a blessing or a curse, aside of specialty applications.

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Klaus Heyne
German Masterworks
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