Something you might not know about condenser microphone capsules

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Marik said:
If my memory is not that rusty, the oxide is a chemical composition of oxygen and some kind of material. The part of the picture you show contains Mylar, as well as plastic (the clamping ring), which both to my knowledge are immune to oxidation (i.e. fusion with oxygen).

Furthermore, Gold (the Mylar coating) is not a very easy metal to get oxidized, either. In the pictures you posted above I am still trying to understand what is wrong with those capsules, as apart from slight signs of Gold peeling (most likely amateurish attempt to clean), they all look they should work just fine.

Best, M
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Hi, Mark,

I agree with you that gold does not get oxidized easily, but I could not find a better term to match with what I see in some old capsules. Maybe you can help me come up with one? What would you call the grayish rusty stuff on top of the diaphragms' golden coating?
 

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Well some condenser microphone manufacturers offers a lifetime warranty, in some way that settles down this issue

Check out JZ Microphones which produces only condenser microphone and offers lifetime warranty for some of their microphones, there's a video on youtube about them, called JZ Microphone Product Video (just joined this forum, can't post URL)
 
Twinhit said:
How about those foam filters that hide the grille?

Seems to me constant use of a foam filter would help keep the capsule clean if not somewhat drier from airborn
dust and humidity.
I could be wrong and if so, I would like to know why.
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Actually, condensers don't normally use foam - mostly it's a fine gauze.

And foam is actually not very good as it deteriorates with age and disintegrates. This action would actually cover the diaphragm with foam-dust particles.

One other point of note - a normal AF condenser mic. actually attracts dust and particles to the diaphragm by electrostatic action (but not RF condensers as they work in a different way).
 
Browneyes said:
Hi, Mark,

I agree with you that gold does not get oxidized easily, but I could not find a better term to match with what I see in some old capsules. Maybe you can help me come up with one? What would you call the grayish rusty stuff on top of the diaphragms' golden coating?
Click to expand...

Usually, on the capsules they call it contamination. It seems the lower capsule suffers from bad cleaning attempt.

Best, M
 
Harvey Gerst said:
They sent me a couple of their mics to evaluate - a D36b, and an L36b. I plan to give them a listen in the next few days.
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Thanks Harvey!...very interested in your thoughts, and if possible, some sample files...the idea of an Aluminum capsule is interesting and as I stated in my previous post, hearing is believing...
 
The sE titan is supposed to be a titanium coated element. Lighter then aluminum iirc. Or I could be wrong.
 
I am still a bit baffled by the somewhat hostile responses you got, Browneyes. I am no fan of China-made gear, but if kidvybes had not "outed" you, no one would know- nor care, I suspect.
 
Shadow_7 said:
The sE titan is supposed to be a titanium coated element. Lighter then aluminum iirc. Or I could be wrong.
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Really, in this application the material mass does not that matter, as the layer thickness is just of some 25-100 Ångström, which is negligible.

Best, M
 
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.........


So here comes the inevitable question: is there anything we can do to change this? Is there some kind of physical mechanism that can keep the “resistor” at a very high resistance level no matter how the environment condition changes? Well, in the past decades, microphone designers have tried different methods in attempts to do so. This topic is a little complicated, I will come back to it later.

Now let’s have a better look at a capsule first.

As you can see, the diaphragm is actually stretched to a specified tension and glued to a ring, which is then attached to the back plate with screws. Notice the material of the ring? It is made of ceramic, or plastic. But it used to be metal. You maybe wondering why ceramic and plastic are chosen over metal. The answer is that metal is conductive. The ring, with the diaphragm, is to be screwed to the back plate. If the ring itself is made of metal, then it will become part of the back plate, and then, the distance between the diaphragm and the back plate would be shortened to the edge of the golden layer and the inner side of the ring. By using ceramic or plastic to make the ring is making that distance longer, which makes it harder to form a circuit loop, and makes it less likely to crackle. And hence increase the microphone’s life span.
 

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Marik said:
Really, in this application the material mass does not that matter, as the layer thickness is just of some 25-100 Armstrong, which is negligible.

Best, M
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I respectfully disagree. If you're going to be sympathetically vibrating 20,000 times (20kHz) a second, any mass difference no matter how small will matter. Otherwise mics would never be affected by humidity and other factors. I mean if air pressure can change the speed of sound by a hundred feet or more per second(~10%), what's the thickness of air relative to the mics material? And if you need a thicker than ideal mic material so that it ages well, which material best suits?
 
Shadow_7 said:
I respectfully disagree. If you're going to be sympathetically vibrating 20,000 times (20kHz) a second, any mass difference no matter how small will matter. Otherwise mics would never be affected by humidity and other factors. I mean if air pressure can change the speed of sound by a hundred feet or more per second(~10%), what's the thickness of air relative to the mics material? And if you need a thicker than ideal mic material so that it ages well, which material best suits?
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May I remind, we are talking about masses which are BY FAR less than the mass of loading air, so what is it? 10mHz? 500mHz? 1gHz?... or just pick your number. It is the same if somebody farts in NYC, theoretically the content of the air will change on West Cost. But it really does not matter whether one had a curry dinner, or just visited Nobu in Tribeca. In other words, for all practical purposes, it will be quite hard to find out the difference of the impact on the world atmosphere between the fart from a heavy curry dinner, or light sushi.

The 20kHz resonance is nothing even for 2um ribbon and we are talking thicknesses of 10nm (i.e. 10^-8 m (!!!)). Heck! Some measurement capsules go up to 100kHz, having "extremely heavy" 4um (!!!) Nickel diaphragm, which BTW, is thicker by MILLIONS.

The humidity is completely separate and unrelated matter.

Best, M
 
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We are actually talking about two different things, solid metal foils as membranes vs. sputtered metals on mylar. The density of these metals is 2x to 3x that of mylar. So it's down to the thickness of the material, mylar is 3 to 6 micron, the figures I can find for the foil membranes is 0.6 to Marik's 4 micron figure for the bulletproof measurement types. Thus, I don't see a reason why a foil is necessarily lighter than mylar, although that may be true for two given capsules. And of course there is tension to be considered . . .

If you've ever worked with 0.6 micron foils . . . well, I am not in a hurry to use that in a microphone. I mean mylar can survive being touched by a brush, try that with a 0.6 micron foil and you may soon be cleaning the pieces of diaphragm off of the backplate . . .
 
The density of Al is 2.70, Au 19.32, PET (Mylar-My)1.39, Ni 8.91. In other words, PET is about twice lighter than Al and 6.4 than Ni.
And yes, apart from being a major PITA, no problem working with 0.6um foil. It takes quite awhile to set the corrugator.

Best, M
 
Been there done that ain't gonna do it no mo'! On that topic, you got any corrugated 2.5 micron foil you can sell me? I don't have my old corrugation rig (a Yamaha keyboard modulation wheel, if you can believe that) anymore :( I don't need much . . .
 
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