rebuilt capsules

I have some questions.

When I go to other web sites I often find statements by "pros" that no reskinned capsule sounds like the "real" capsule. Some that come to mind are the brass versions of the CK12 and K87 and K89 capsules.

I can understand ones being done by SPA being different because of the changes.

I don't understand when the skin is the same thickness and same tuning frequency/ tension. PET is PET as far as I know.

I have a reskinned K67 that sounds fine it sounds like a k87 k67 capsule to me

If someone heat treats and tensions and uses the same materal and then graphs the capsule why do people say the "real" ones sound different. Capsules are not magic.

Is it the brass ck12 has not been made after about 1982
and the stuff in the world is stretched and "work treated" by being used??
this would not be the true new sound I would think.

Is it to keep a "magic" story thing going?

The older u87s I have been inside all seem to have a front skin with less tension sometimes the holes mark the backside of the PET. how can this be good.

My capsule was rebuilt by Doug Walker. Does anyone have microphones that have been rebuilt by say Korby or SPA that would like to share some information.

I can understand if someone that not rebuild the capsule correctly it not sounding good but some of the people rebuilding capsules must be doing close if not like what Neumann and AKG do/did.

I never saw an answer with science behind it why it does not sound right, just it sounds different.

Gus,

I have a 414 with a brass CK12 that Klaus did his treatment to. He reskinned the back diaphragm and whether or not it sounds real, it certainly sounds great. If I remember correctly, he did express some concern, but it worked out fine.

:thumb: :thumb:

I have been curious about this as well. It doesn't seem that tough to do the work (making diaphragms and putting them on) so why is there nobody that can apparently re-do a diaphragm?

On the AKG CK12 capsule you have many tuning areas, so I can see a re-skin job not being so easy because you probably need to re-set some of the shims within the capsule after measuring the diaphragm's response. It seems as though the shims are pretty critical from what I can see and hear.

-Dale

[quote author="dale116dot7"]I have been curious about this as well. [/quote]

Ditto!

My guess, in some circles, for some reason (actually, quite understandable), there is a tendency of putting some mistery on some aspects of microphones. This sheer commercial and personal interest is quite transparent to me. Feel free to correct, if you think I am wrong.

Hi
My friend Thomas sent me two broken Generis GC-1 mikes to use chassis for my microphones.
One of capsule is not broken but another is like this:

Just to know can I do it anything with this. In any case I will use better capsule but I am curious.
Chassis is nice and look like ADK and MXL (similar).
Duka

whats wrong with that cap? is that a light reflection on the left of the gold or is that a wrinkle? i've seen a couple of m7 caps with wrinkles in them and i *believe* to an extent they are cosmetic (i'm probably wrong).

[quote author="asm"]whats wrong with that cap? is that a light reflection on the left of the gold or is that a wrinkle? i've seen a couple of m7 caps with wrinkles in them and i *believe* to an extent they are cosmetic (i'm probably wrong).[/quote]
It is wrinkle :sad: Capsule works :shock:

[quote author="Gus"]I have some questions.

PET is PET as far as I know.

[/quote]

Gus, I've been thinking about this. Here is my $0.02. PET is possibly not the same as it was "back in the day". I'm not an expert on PET manufacture and it's history, but here is what I do know. PET can vary by the following parameters:

1. Degree of crystallinity and degree of polymerization (unreacted or prematurely terminated monomer)
2. Molecular chain length distribution, dispersity index
3. Plasticizer, initiator, and reaction solvent species
4. Processing effects on strand orientation, tensile vs. hoop stress ratios, blown film vs. extrusion processing, etc.
5. Post treatments, including heat treatment, heat stabilization (different than treatment), corona treatment, flame treatments, etc.

In my work (printed electronics) we see different adhesion characteristics of our printed metals to different vendor's PET offerings. Dupont alone offers Melinex and Mylar in over 930 grades. There is an Italian company called Coveme that makes PET that behaves very different than the Dupont brands too. A lot of graphics printers I've spoken with like them because their films are cheap, with better performance for ink reception.

That being said, I am still skeptical about not being able to re-skin a capsule to get it to sound like an original capsule. I often disagree with the "older-is-better" school. You also made a great point about original capsules not sounding like original capsules, what with 30-50 years of spit, smoke, pollution, polymer degradation, visco-elastic relaxation, and mechanical damage. If this is a key part of the vintage sound, we might want to try re-skinning capsules with a Dorito bag (aluminized Mylar). It's nice and thick, greasy, gets exposed to lots of handling and shock, and probably is a lower grade of polymer than a modern engineering-grade PET. Just kidding. :wink:

That being said (again), I did hear a re-skinned U-47 that didn't sound quite right. Not that I am an expert on vintage U-47's, but this one sounded kind of bad. I've liked every other U-47 I've heard, both vintage and FET. Was it the PET or was it the work? I'm not sure, but it was done by one of the big-name restoration guys. No mods were allegidly done either.

-Chris

[quote author="Emperor-TK"]
That being said (again), I did hear a re-skinned U-47 that didn't sound quite right. Not that I am an expert on vintage U-47's, but this one sounded kind of bad. I've liked every other U-47 I've heard, both vintage and FET. Was it the PET or was it the work? I'm not sure, but it was done by one of the big-name restoration guys. No mods were allegidly done either.
[/quote]

Chris,

Was it M7, or K47? The first, as you know, used PVC, so replacing it with Mylar changes things completely, or just a job...

It's not really cosmetic - the diaphragm tension isn't right, frequency and polar response won't be quite right, but the mic will continue to work. It's sort of like a drum head if you take out two (adjacent) tuning lugs. It needs a new diaphragm. Technically it needs the diaphragm to be re-tensioned but you can't do it once it has been trimmed. Either the diaphragm was not glued to a retainer ring, or if it was glued, the glue isn't holding any more.

I would guess it's the work - if I had to take a guess I'd say the diaphragm was likely over-tensioned, or maybe if it was the M7, the ring area was not cleaned sufficiently and either glue got underneath, or the diaphragm spacing could be affected.

Duka,

I have a CK12 capsule from a vintage AKG C12 that looked the same like in your picture.
Dale is right, the glue was not holding the menbrane so only a relaping can help.

chrissugar

[quote author="Marik"][quote author="Emperor-TK"]
That being said (again), I did hear a re-skinned U-47 that didn't sound quite right. Not that I am an expert on vintage U-47's, but this one sounded kind of bad. I've liked every other U-47 I've heard, both vintage and FET. Was it the PET or was it the work? I'm not sure, but it was done by one of the big-name restoration guys. No mods were allegidly done either.
[/quote]

Chris,

Was it M7, or K47? The first, as you know, used PVC, so replacing it with Mylar changes things completely, or just a job...[/quote]

Good point Marik. I'm not sure what capsule was in it and wouldn't be able to distinguish the sound of an M7 from a K47 anyway. I don't have enough experience with the U-47. I use a 47Fet at a friend's studio occasionally, but have only used a tube 47 a few times, and not too recently. I'm not sure what mics had what capsules.

-Chris

Emperor-TK

I guess we would need to find out what brand and type of PET Neumann and AKG use/used. Funny thing even new capsules are said not to sound the same when reskinned.

Would your points 1,2 and 3 be less of a "problem" with more modern tech?

Point 4 I think the dupont stuff has two grain directions W and L

I believe good capsules are heat treated at 80C to relax the grain 80c is Tg for PET I believe. Whats corona and flame treatment? point 5

Would the different PET mixes have different density and mass?

[quote author="Gus"]When I go to other web sites I often find statements by "pros" that no reskinned capsule sounds like the "real" capsule. Some that come to mind are the brass versions of the CK12 and K87 and K89 capsules.[/quote]

Um, not for nothing, but which pro's have a vintage capsule that has been vacuum sealed since 1960 which they open, on occasion to make judgements on what a "real" capsule should sound like.

Im not a collector nor am I a mic technician and by and large I see this entire debate's relevance completely lost on a world that those two labels dont describe.

I have ck12 capsules that were rebuilt by tracy korby. I have never ever ever not even half a time heard any mic that sounds as good as the pair I sent to him. They dont sound like every other ck12 I have heard. They sound worlds and worlds and worlds better. I dont give a fuck that they dont sound like other ck12's.

I think more people need to come to terms with the fact that micrphones have a finite life span, especially if they have been used predominantly for vocals over the mics lifetime. What these things are supposed to sound like becomes largely irrelevant if the mic doesnt sound good in the first place because of age. I have lots of vintage mics that dont sound good and I dont use them. whats the point in that, you know?

Every time this comes up and some mic guru opens up on how reskinning a capsule will change its sound I have to laugh. Think of how many people out there eat that shit up and dont reskin their mics and instead suffer with an old vintage mic that doesnt sound good at all simply because they want to keep it vintage. This logic has always and will always baffle me. So sure, if you reskin your capsule it will sound different. who cares. If the mic is crappy, wouldnt you reskin it if it makes it sound BETTER? I do. I change the ribbons in my old ribbon mics too. More folks should be concerned with using the gear and optimizing it to function. There are few 50 year old mics out there that wont benefit from a rebuild. Few.

Anyhow, tracy korby is a genius, whatever that guy does, its ILL. the fact that he doesnt spend half his day on the internet telling people the rules of microphones is really really appealing as well, but maybe thats my personal attraction to the guys work ethic. I say "hey man, make this old piece of junk soundd better" and I get a mic back that sounds better every time, so far he is 4 for 4 with me.

sorry to dump my emotional and not scientific reaction in this thread. If PET is PET of if old PET is better is a good discussion, but when your mic is worn out and sucks, brand new PET is probably better than whats wrinkled up on there in the first place, right? All the people that hold on to the past with electronics change the oil in their cars I bet. Its just so wierd to me.

dave

Dave I think your points are right on the mark.

A reskinned bad old capsule is better than it was. And Again who KNOWS what a new brass CK12 sounds like? they have not been made for years, 1982 is the last year if what I read it true.

All I know is I like my 800 type microphone with my Doug Walker rebuilt k67 capsule when placed next to my VM1.

dave,

if you dont mind me asking... how much does korby charge for a reskin on the ck12? i have no idea and was just curious.

stupid question....but spacing, hole dimensions and number of them would have a more dramatic effect on the reproduction of sound compared to the diagphram material? or no?

dale, didnt you sucessfully get nickel on one of your caps? how does the technician determine how thick the deposit of material on the diagphram is?

always like to learn :thumb:

[quote author="asm"]stupid question....but spacing, hole dimensions and number of them would have a more dramatic effect on the reproduction of sound compared to the diagphram material? or no?
[/quote]

Hahaha,

Not that stupid of the question. In fact, it is right on...

[quote author="asm"]if you dont mind me asking... how much does korby charge for a reskin on the ck12? i have no idea and was just curious.[/quote]

wow, its been a while, I honestly dont remember. However much it was, a)it wasnt a big deal to send the mics out, ie, it wasnt prohibitively expensive to consider sending them out for service to him and b)when I got the mics back I remember thinking what a great value I got for my money. As for the exact price, I really dont remember. I know they are moving to TN right now, call them after April 1st and ask, nadine who does the customer service is so incredibly nice and helpful. Good people to do business with so far that I can tell. Im looking forward to sending my 563's, I was gonna do them myself but I just dont have time and he'll do a better job than me anyway...

dave

thanks man. will do just that.

are your getting your 563 body modded or the cap or both? what caps do you have along with it? m7/8/9?

heres a question for ya....if you have the m9, whats that mic+capsule combo sound like? decent? doesnt the 563 body kind of suck? would that capsule sound nice behind a nice solid schematic?

:guinness: