K67 capsule mod for less high end

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GeorgeToledo

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bockaudio said:
In terms of vintage mics? Of course, the plastic, and all the plastic parts ARE different and aged. Does burn in matter on a new mic is the harder to answer question, and then, is the capsule separate from the electronics in that regard?

I had meant this in context of someone having brought up whatever Klaus could be doing when their new capsule gets “vintage tuned” by him. A bit of a mystery to what that means.

So I just think to the low hanging fruit. Replacing the actual capsule with a NOS one is a possibility, but I am guessing someone might say “hey the numbers on this capsule are different!”. Or not.

But it came to mind that many years ago on the George Massenburg forum, I think he wrote about using a hair dryer (no heat) to test tension. So, again, thinking to “low hanging fruit” of what someone might think to do in order to somehow relax the tension of an assembled capsule, it had me contemplate that maybe he is blasting the capsules with air for awhile.

Or doing some other type of “burn in” level treatment, maybe just sound.

I guess it IS possible to test the capsule to see if the resonant frequency has actually lowered, and if “low end extension” is truly gained.

My understanding is limited for sure, but it seems that lowering resonant frequency also can possibly move the corner frequency up in the high end down to a lower frequency, and maybe into an uglier place.

Maybe even something like the epoxy technique in the original post is happening.

Just as likely it is none of this.

My personal logic with something like this is more like, if I bought a new U67 and it wasn’t satisfactory - and I really thought it was an issue with the capsule - I would probably send it back. It’s plenty of money to spend and I would try to take advantage of the warranty. But to each their own. It gets a bit philosophical.

I think you are right to raise the issue of how much is “burn in” about usage, vs simply the aging of materials. The aging of materials themselves can be pretty significant in some cases, though usage can definitely be a factor other times (hours of tube usage for instance).

I have some Shure 57s and 58s from the 90s that mostly sat in a drawer, and that I think sound much more like US Unidyne III era after aging a few decades. In that case, usage had little to do with it. I don’t have any tests I can show to demonstrate this in an objective way, so take it with a grain of salt I suppose.
 

GeorgeToledo

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One thing that occurs to me about the modification of capsules, whether it is backplate, or some unknown method of “relaxing tension”, new diaphragm material...

If the modification isn’t the exact same on the front and back of the capsules, it is going to destroy polar pattern uniformity.
 

Tim Campbell

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bockaudio said:
Priceless.
Well you got me on that David. Poor choice of words but you understand my meaning. A capsule shouldn't be expected to last forever.
I get this all the time. A client sends a 10 year old capsule back to me because it began to get noisy.
In what other industry would a client send a part back for warranty repair simply because it showed signs of normal wear.

I find it quite funny too that a third party can go to a manufacturer and tell Neumann for example that their capsule doesn't sound like a Neumann capsule. Whose product is it? Who defines it's characteristics? If it is altered outside of their spec does it then sound like a Neumann capsule? I would never think it would be a good idea to let a person who doesn't build and have a deep understanding of how capsules work to mod an expensive one. David Josephson used to say that if you aren't capable of repaing a capsule you have no business taking chances with it. This is not a reference to the changes made to the capsules here.

I never saw an SPA modded capsule that in truth wasn't destroyed. He would lap the backplates until there was almost nothing left of them.  Stephen and I had many great discussions but at the end of his life his behavior became unpredictable.
 

Recording Engineer

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bockaudio said:
Remember he destroyed all those Neumann made capsules in order to use thinner membranes. Never made his own backplates.
If you re-membrane one of his destroyed backplates with the old, original thickness you don't get the original response. The worst of both worlds.

Well, according to Klaus (and Neumann?), you never will by reskinning; so pretty moot if that’s the case.

Anyhow, about him never making his own backplates, easy thing to say here in 2021 and with reasonably decent health.
 

bockaudio

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Tim Campbell said:
Well you got me on that David. Poor choice of words but you understand my meaning. A capsule shouldn't be expected to last forever.
I meant it as a compliment.

I find it quite funny too that a third party can go to a manufacturer and tell Neumann for example that their capsule doesn't sound like a Neumann capsule. Whose product is it? Who defines it's characteristics? If it is altered outside of their spec does it then sound like a Neumann capsule?
Well, also, Monday morning quarterbacking. When the critic has their own line of products I'll take interest.
I would never think it would be a good idea to let a person who doesn't build and have a deep understanding of how capsules work to mod an expensive one. David Josephson used to say that if you aren't capable of repairng a capsule you have no business taking chances with it. This is not a reference to the changes made to the capsules here.
Yeah but if Klaus never experimented with backplates he never would have come up with the KHE, which has the highest resale of any modern production mic.

I never saw an SPA modded capsule that in truth wasn't destroyed. He would lap the backplates until there was almost nothing left of them.  Stephen and I had many great discussions but at the end of his life his behavior became unpredictable.
"unpredictable"...too polite!  ;) Those backplates are by definition destroyed, there is no way to return them to original.
 

bockaudio

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Recording Engineer said:
Well, according to Klaus (and Neumann?), you never will by reskinning; so pretty moot if that’s the case.
"reskinning" gross.
Well if Klaus said it then it's end of discussion.

Anyhow, about him never making his own backplates, easy thing to say here in 2021 and with reasonably decent health.
Meaning?
 

Recording Engineer

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Well I personally don’t believe one way or the other on re-skinning, as I don’t know or actually care at all anymore; though I have a few re-skinned capsules that I love, if that points in any direction.

Really, with people such as yourself producing such great currently manufactured products out there nowadays, I’m long past caring about vintage, other than for personal museum collections; something I’m not interested in trying to afford and leave it to those who have both the desire and finances.

As for meaning, who was making their own backplates from scratch in the 80’s and 90’s? Certainly wasn’t individuals. More like very-long-standing companies (or derivatives of, or employees who branched-out on their own), as well as Communist government -backed companies. Of course, there’s outliers (Josephson, off the top of my head), but for the most part, it wasn’t until the widly-free information sharing around the globe, through the internet, did things really begin to take-off. Stephen was very sick from the start of it and has been long gone.

Things are easy to say here in 2021, where things are taken for granted now. Who knows where Stephen could have and would have taken things, given life, health and resources that have become so widely available.
 

abbey road d enfer

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Tim Campbell said:
Well no one should expect a microphone capsule to work for an indefinite period of time. The fact that many of them work flawlessly for decades is to their credit but they are manufactured within practical restrictions to serve their purpose reasonably. Very few capsules except for measurement purposes are manufactured to an ideal.
That's easy to see just from their varied frequency response.
Let's celebrate their flaws and fragility.
These are two different subjects.
Durability: what are the mechanisms that make capsules ageing in normal conditions?
Dirt and spit; AFAIK this is fixable.
Material ageing: excluding PVC, the life expectancy of plastics is on a millenial scale. Metal/ceramic on an archeological time frame. In most cases, material ageing does not result in malfunction.

Reproducibility/imperfection: just a fact of life. Not all capsules are born equal, but it shouldn't result in some dying early. Except gross defect.
 

shabtek

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abbey road d enfer said:
These are two different subjects.
Durability: what are the mechanisms that make capsules ageing--
--
Material ageing: excluding PVC, the life expectancy of plastics is on a millenial scale. Metal/ceramic on an archeological time frame. In most cases, material ageing does not result in malfunction.
that may be an oversimplification, especially considering the fine structures involved: I am thinking of adhesive break-down, potential for fouling of sputtered plastic from various environmental influences from time of  manufacture and during product life.  possible changes imposed by thermal, chemical and mechanical modes, to sputtering, and at the perimeter of diaphragm where mechanical forces determine tension_
 

Tim Campbell

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abbey road d enfer said:
These are two different subjects.
Durability: what are the mechanisms that make capsules ageing in normal conditions?
Dirt and spit; AFAIK this is fixable.
Material ageing: excluding PVC, the life expectancy of plastics is on a millenial scale. Metal/ceramic on an archeological time frame. In most cases, material ageing does not result in malfunction.

Reproducibility/imperfection: just a fact of life. Not all capsules are born equal, but it shouldn't result in some dying early. Except gross defect.


Gross defect? Almost all your household items are made from these very same materials yet you do not find it unusual when they breakdown after their warranty period. Why should it be unthinkable that a capsule could break down after a similar period of time without claiming defect?

Try complaining to Neumann that your capsule stopped working after 3 years because of some gross defect on their part. I am not even sure they would answer you.

That well made capsules work without problem for many years is a blessing really. That many boutique manufacturers give good warranties and service is to their credit. I can't think of many other areas where manufacturers would be under any obligations after 2 years.

"In most cases, material ageing does not result in malfunction." Unfortunately ageing of the plastic on CK12 capsule is one of the largest contributors to their failure.
 

abbey road d enfer

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Tim Campbell said:
Gross defect? Almost all your household items are made from these very same materials yet you do not find it unusual when they breakdown after their warranty period.
Failure in these household items is essentially related to wear of moving parts submitted to friction or electrical/thermal overload. Nothing of that sort in a decent mic capsule in normal conditions.
The larger the number of parts, the higher the risk of failure, that's why a knife is very reliable; the same goes for mic capsules.

Try complaining to Neumann that your capsule stopped working after 3 years because of some gross defect on their part. I am not even sure they would answer you.
Legality/liability has nothing to do with failure analysis. I'm not asking for lifetime warranty of mic capsules. I'm just saying a capsule that doesn't work after 3 years has either been misused or suffered bad manufacturing.

"In most cases, material ageing does not result in malfunction." Unfortunately ageing of the plastic on CK12 capsule is one of the largest contributors to their failure.
I'm not aware of such a phenomenon happening in just a few years.
 

Tim Campbell

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"I'm not aware of such a phenomenon happening in just a few years."
You obviously don't work with acrylic then :)

Any machining of acrylic results in built up tension within the material. This can sometimes be mitigated by heat but any exposure to a solvent such as alcohol can result in severe cracking of the plastic even within minutes or within months. I mention this here and to my clients repeatedly.

Unfortunately people use isopropyl within microphones all the time without realizing the risk. The same is true of overtensioning plastic parts when installing them.

Other materials could be used but then it would stray from the original production method and would change the cost
 

abbey road d enfer

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Tim Campbell said:
"I'm not aware of such a phenomenon happening in just a few years."
You obviously don't work with acrylic then :)
Just to make it clear. I don't make, repair, modify or even touch mic capsules. I used to clean capsules about 40 years ago, using cold sulfuric ether vapour.

Any machining of acrylic results in built up tension within the material. This can sometimes be mitigated by heat but any exposure to a solvent such as alcohol can result in severe cracking of the plastic even within minutes or within months.
This is clearly malpractice, and indeed, as such should not be covered by warranty.
 

LevinGuitar

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A link to a good view of the K103 backplate holes design:


As far I know the TLM103 have nothing of the de-emphasis in the circuit, so the K103 capsule have to be less bright. I really want to try it in a tube mic circuits. Any experience with it?
 
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Recording Engineer

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I’ve been wanting to try it in a tube circuit as well for years, but still never have; too many things of wanting to try. I’ve always thought an M49b or C37a -inspired direction.
 

mhelin

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A link to a good view of the K103 backplate holes design:


As far I know the TLM103 have nothing of the de-emphasis in the circuit, so the K103 capsule have to be less bright. I really want to try it in a tube mic circuits. Any experience with it?
Isn't there a 1nf in series with 220 ohms resistor to ground LPF between the 2nd FET the first PNP?
(found a trace of the circuit here: Neumann TLM 103|102 + Neve 1073 + Redd 47, isn't it for TLM 103 as 102 has some epoxied areas which cannot be traced)
 

abbey road d enfer

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Isn't there a 1nf in series with 220 ohms resistor to ground LPF between the 2nd FET the first PNP?
IF this schemo is correct, the whole circuit is a voltage-follower. The RC circuit is there for creating the dominant pole needed for stability, and the frequency response is straight as an arrow.
 
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