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Author Topic: Gefell CMV 563 M7S capsule  (Read 6618 times)

aremos

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Gefell CMV 563 M7S capsule
« on: February 25, 2014, 02:45:11 am »

Klaus has stated that Gefell made the original PVC M7 until about 2005 and that the current capsules exhibit some low-end loss, and other slight timbre changes, due to new PVC material they are using, and the retirement of the long-serving craftsman.

Does this apply to what they are describing as an original reissue of the M7 capsule in their CMV 563 - M7S mic?
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klaus

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Re: Gefell CMV 563 M7S capsule
« Reply #1 on: February 25, 2014, 01:43:35 pm »

MG's CMV563 M7S is a recent re-issue of a mic closely related to the UM57 (and also quite similar to the UM92). I went to their website and cannot find any hint that the M7 PVC capsule used in this re-issue  differs from the PVC M7 capsules MG use on their other products. It also seems that very few dealers in the U.S. carry that model (as far as I know, MG does not use the traditional system of importers or distributors for the U.S. market), so it is not readily available for testing or further investigation without some effort or outright purchase of the mic.

Due to my critical comments about MG's latest version of PVC M7 (stemming from personal experience and measurements), I also do not have the goodwill of the company any longer, to just ask them for a sample, to find out whether the current M7 production has changed back to its previous excellence.

Current, environmentally sound PVC material is different enough in composition from the material whose chemical component has been discontinued, due to toxicity. That means, regardless of who manufactures a PVC membrane as substrate for sputtering and diaphragm use today, they will have to re-think the approach to restoring PVC M7 excellence.

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Klaus Heyne
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jeri

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Re: Gefell CMV 563 M7S capsule
« Reply #2 on: February 25, 2014, 02:00:13 pm »

"Due to my critical comments about MG's PVC M7 (stemming from personal experience and measurements), I also do not have the goodwill of the company any longer..."

Wow.  Does this imply that MG will provide product information only if it is assured in advance of a positive review?  I find this attitude disturbing.  Is it typical of other manufacturers?  I would have hoped that reputable vendors would welcome all knowledgeable and honest criticism and would seek to improve products instead of suppressing negative comments.
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klaus

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Re: Gefell CMV 563 M7S capsule
« Reply #3 on: February 25, 2014, 02:21:49 pm »

It seems to defy logic: why would a manufacturer not want input from qualified, detailed criticism, in order to get solid feedback or to improve a product?

But can you give an example where a product from an established company was critically reviewed, and the reviewer retained goodwill and cooperation with the company afterwards? Hence the system of backstroking reviews in all magazines- print or online: I give you a good review, and you give me advertising dollars.

So, I think, the response I got is pretty much the norm (though, in this case, I could not even be accused of trying to discredit the competition- I don't make or sell capsules).
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Klaus Heyne
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aremos

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Re: Gefell CMV 563 M7S capsule
« Reply #4 on: February 26, 2014, 10:40:43 pm »

Current, environmentally sound PVC material is different enough in composition from the material whose chemical component has been discontinued, due to toxicity. That means, regardless of who manufactures a PVC membrane as substrate for sputtering and diaphragm use today, they will have to re-think the approach to restoring PVC M7 excellence.

Klaus, would this include the Thiersch PVC?
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klaus

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Re: Gefell CMV 563 M7S capsule
« Reply #5 on: February 26, 2014, 11:28:41 pm »

Yes. Thiersch manufactures in a country, Germany, which forced the change, due to environmental concerns, in its western part decades ago. That allowed East Germany (Microtech Gefell, in this case) to continue with their excellent M7, despite the toxicity during its manufacture for a few more decades.

A few years after East Germany was unified with the West, the same environmental laws were mandated in the new states, too, and some of the volatile components in PVC manufacturing were discontinued and substituted, once they ran out. It would be interesting to cast PVC foil with the old stuff, if some of the discontinued ingredients could be found, and used.

But there is more to the story: You also need intuition, a musical ear, and willingness to experiment with new formulas, if you truly were trying to recoup the excellence of the original product. In my conversations with those at the levers of M7-type capsule manufacture I currently do not recognize the presence of all three.
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Klaus Heyne
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boz6906

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Re: Gefell CMV 563 M7S capsule
« Reply #6 on: February 27, 2014, 08:34:45 am »

I hesitate to say this, but...

Given China's lax enforcement of environmental regs it would seem a prime location to produce the original PVC formula.
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aremos

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Re: Gefell CMV 563 M7S capsule
« Reply #7 on: February 27, 2014, 12:35:37 pm »

Good point!

But then there would be other factors to worry about ... quality control, etc.?

Does the US have the same ban on this chemical that makes up the PVC also?
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boz6906

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Re: Gefell CMV 563 M7S capsule
« Reply #8 on: February 28, 2014, 10:58:07 am »

I know there are many regulations concerning PVC in the US.

"Some major manufacturers, retailers and companies are moving away from using PVC due to concerns about the toxicity of PVC and many of its additives, including phthalates which are required to make PVC plastic more soft and flexible."

Here's some info:

http://www.saferchemicals.org/resources/vinylchloride.html

My understanding is that the chem companies have an oversupply of chlorine (mostly from splitting sodium from salt for other products) and they shove the chlorine into the plastic to dispose of it.

As the PVC slowly breaks down it out-gases chlorine, ethyline dicloride and vinyl chloride monomer, all carcinogens.

Hmmmm, back in the day, a vocalist close-working a newly manufactured U47 was inhaling carcinogens...

Could lead to higher incidence of throat/lung cancer in vocalists.

Levon Helm, Donna Summer, Nat Cole, Jacques Brel, Carl Wilson, Roy Orbison, George Harrison...

Wow, I don't want to think about this anymore...
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aremos

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Re: Gefell CMV 563 M7S capsule
« Reply #9 on: February 28, 2014, 02:37:02 pm »

Yeah, but how much exposure would you really have to go through to get sick?

So, the conundrum would be that if we use the old M7's it sounds better but there's toxicity exposure and if we use the "new" ones the sound suffers but it's "healthier"?
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jeri

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Re: Gefell CMV 563 M7S capsule
« Reply #10 on: February 28, 2014, 09:49:18 pm »

No, no, no!  Chemical companies DO NOT shove chlorine into plastics to dispose of it.  The Chlor-Alkali industry makes chlorine and caustic soda (sodium hydroxide) from sodium chloride salt.  Both are valuable and are sold to other companies for a lot of different uses.  Since the process makes a fixed ratio of chlorine and caustic, chemical pricing is set by the market to keep demands for these product chemicals in balance.

One of these uses is to react chlorine with ethylene to make vinyl chloride. Vinyl chloride is a gas at room temperature and has exactly one atom of chlorine per two atoms of carbon.  Vinyl chloride is a monomer (called vinyl chloride monomer or VCM) which can be polymerized in a pressurized reactor to make polyvinylchloride (PVC).  The resulting PVC resin has a long chain carbon backbone with a chlorine atom on every other carbon atom.  Unreacted vinyl chloride is recovered as part of the manufacturing process because it is a valuable raw material.  VCM is a carcinogen so emissions are regulated to minimize plant personnel exposures.  PVC resin is a powder and contains less than one part per million residual vinyl chloride. 

Final PVC products are made from PVC resin plus a variety of additives including plasticizers, stabilizers, lubricants, and fillers to make a material with the desired physical, mechanical, thermal, electrical, and chemical properties.

As PVC ages, volatile materials can certainly out-gas.  But chlorine gas or ethylene dichloride are not among them.  Chlorine is used in the production of VCM and ethylene dichloride is an intermediate product in the production of VCM, but neither are present as individual compounds in PVC resin.  There could be traces of unreacted VCM, but there isn't much there to begin with.  There can be a lot of plasticizer in flexible PVC film or tubing.  Plasticizers are volatile organics and they are not strongly bound to the PVC polymer, so they can gradually migrate out of the PVC.  Some short-chain, lower molecular weight phthalates such as DEHP are suspected as endocrine disruptors or reproductive toxins, but they are not carcinogens -- at least not in humans.  Longer-chain higher molecular weight phthalates such as DINP are not considered hazardous.

So singing into a PVC-equipped mic is not an occupational hazard.  Unless you do it in a smoke-filled room.
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aremos

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Re: Gefell CMV 563 M7S capsule
« Reply #11 on: February 28, 2014, 10:04:48 pm »

So, as your last sentence says, and I believe it as it was my gut feeling all along, as far as capsule manufacturing (& singing into it) there really is no harm.
And even if there was truth to it there would have to be a daily-almost-24-hour exposure.

I'm really getting tired of government (& extreme environmental) intrusion & regulation in our lives. And it always begins in Europe.
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klaus

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Re: Gefell CMV 563 M7S capsule
« Reply #12 on: February 28, 2014, 11:01:56 pm »

My understanding is that the volatile carcinogens are most concentrated and harmful in the initial, liquid state of PVC- when it is poured and cast to make the membrane. So using a cured membrane for vocals should not be an issue.

Developed societies appoint government as our representative to administer the protection of individuals' health when corporations do not see fit to intervene early and forcefully. The asbestos tragedies that cut short the lives of many thousands in the last century should be argument enough for the regulation of certain materials.
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Klaus Heyne
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soapfoot

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Re: Gefell CMV 563 M7S capsule
« Reply #13 on: March 01, 2014, 07:08:37 am »

jeri, EXCELLENT and informative post. Many thanks!
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boz6906

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Re: Gefell CMV 563 M7S capsule
« Reply #14 on: March 01, 2014, 08:44:49 am »

I do thank Jeri for the organic chemistry info, although I don't share the 'don't worry, all is well' viewpoint.

Cancer, esp childhood cancers, are increasing:

"Over the past 20 years, there has been some increase in the incidence of children diagnosed with all forms of invasive cancer, from 11.5 cases per 100,000 children in 1975 to 14.8 per 100,000 children in 2004."

http://www.cancer.gov/cancertopics/factsheet/Sites-Types/childhood

"I'm really getting tired of government (& extreme environmental) intrusion & regulation in our lives. And it always begins in Europe."

Another sentiment I don't share.
Of course, my view is somewhat biased as I live in southern West Virginia, where unregulated chemical/coal industries recently poisoned 300,000 people with a 'non-hazardous' chemical, sending hundreds to hospital.

Surely, chemical engineers could devise a polymer that's stable, flexible and truly non-toxic?
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