Something you might not know about condenser microphone capsules

......

Before going on with the topic, I want to spend a little time talk about the layer of stuff on top of the old diaphragm. I call it oxide layer, but there are some different opinions and prefer to call it contamination because gold is not easily to get oxidized. I totally agree with the “hard to get oxidized” part. But the “oxide layer” I referred to is not formed of gold oxide, but the oxide of the particles that were trapped on the surface. If you look into the compositions of those particles, you surly will found some metal elements. And after exposed in the air for a while, these metal elements will get oxidized sooner or later. But regardless the duration of time, this layer of oxide will certainly end up reducing the resistance of the “resistor” I mentioned in one of my previous posts.

Hence, I will keep referring to the layer as "oxide layer".
 
John_7408 said:
I do not work for any..
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Why don't I believe you?? I know what city you are in.


John_7408 said:
Chili,
have you ever saw a studio mic mic with 100dB S/N ?
" to a mic, S/N + A weighted noise level =94 dB ", do you agree ? or don't you know?
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Absolutely couldn't care less.

Browneyes said:
......

Before going on with the topic, I want to spend a little time talk about the layer of stuff on top of the old diaphragm. I call it oxide layer, but there are some different opinions and prefer to call it contamination because gold is not easily to get oxidized. I totally agree with the “hard to get oxidized” part. But the “oxide layer” I referred to is not formed of gold oxide, but the oxide of the particles that were trapped on the surface. If you look into the compositions of those particles, you surly will found some metal elements. And after exposed in the air for a while, these metal elements will get oxidized sooner or later. But regardless the duration of time, this layer of oxide will certainly end up reducing the resistance of the “resistor” I mentioned in one of my previous posts.

Hence, I will keep referring to the layer as "oxide layer".
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If it'a gold, then it's not an oxide layer. Probably scum: airborne dirt and moisture. Why would you assume the layer on top of the gold is metal?? Do you always have metal floating around in the air?? Well, you are in China, so that might be true.... Why would you think the layer would affect resistance?? The diaphragm isn't electrically connected to anything, is it? It might affect capacitance, but only a negligable amount.

If anything, I think what Marik said it true... A poor cleaning job and probably removed the gold layer. Now that would change your mic's response.
 
John_7408 said:
seems not careless problem, on the guys website, ( S/N + noise level ) of none of their mics is 94dB.
seems the guy is setting up a new standard.
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.....and, your point is????

You claim not to work for a Chinese mic manufacturer, yet you dissect other Chinese mics and talk incessantly about them. So, what's your interest?? You're not here because you record your songs at home...
 
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Chili said:
... A poor cleaning job and probably removed the gold layer.
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Well, as far as I know, few (if it’s not none) recording engineers will take out the capsule and do the cleaning themselves. They take great care of their mics, may I say sometimes better than they take care of their own eyes. They seldomly lend their microphones (like a U87) to other people, some won’t even let others lay a finger on them. The capsule in the picture was taken out for the first time from an U87ai after been used for 4 years. The owner didn’t even know how to open a microphone. So I don’t think unprofessional cleaning is the answer to what happened to the capsule. And the stuff on top of the diaphragm is not just airborne dirt and moisture, I think.
 

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Browneyes said:
......

Before going on with the topic, I want to spend a little time talk about the layer of stuff on top of the old diaphragm. I call it oxide layer, but there are some different opinions and prefer to call it contamination because gold is not easily to get oxidized. I totally agree with the “hard to get oxidized” part. But the “oxide layer” I referred to is not formed of gold oxide, but the oxide of the particles that were trapped on the surface. If you look into the compositions of those particles, you surly will found some metal elements. And after exposed in the air for a while, these metal elements will get oxidized sooner or later. But regardless the duration of time, this layer of oxide will certainly end up reducing the resistance of the “resistor” I mentioned in one of my previous posts.

Hence, I will keep referring to the layer as "oxide layer".
Click to expand...

Most likely any build-up or contamination on a diaphragm is not some form of "metal oxide". If it were gold oxide it would be dark brownish red, and any other metal oxide collected would appear as a salt.

The things that build up on diaphragms are either spit or electrostatic particles like synthetic fibers, possibly some small metal shavings, but that would be rare. I've seen other things like glue vapors or spray compounds, but again...extremely rare.
 
A normal AF condenser mic. has a very high impedance capsule (GigaOhms) and a fixed charge. This tends to attract dust and the like to the capsule by electrostatic action.

It also attracts cigarette smoke and particles from a smoker (hence the worse contamination on old mics where people were allowed to smoke in the studio). Tar deposits can build up if you are not careful - and if you smoke "other substances" ..........................
 
John Willett said:
A normal AF condenser mic. has a very high impedance capsule (GigaOhms) and a fixed charge. This tends to attract dust and the like to the capsule by electrostatic action.

It also attracts cigarette smoke and particles from a smoker (hence the worse contamination on old mics where people were allowed to smoke in the studio). Tar deposits can build up if you are not careful - and if you smoke "other substances" ..........................
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NO! ~ NO! ..... Don't tell me that pot smoke will destroy a microphone.
That's like finding out that solent green is made from people. :eek:
 
moresound said:
NO! ~ NO! ..... Don't tell me that pot smoke will destroy a microphone.
That's like finding out that solent green is made from people. :eek:
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Not the whole microphone - just the capsule.

When an expert tries to clean it, the sticky stuff normally pulls the gols spattering off and the capsule then needs replacing. :(
 
Yes sorry for the spelling error. But the time set was in 2022 but for how long before that was it available and possibly under a different name like Mc Donalds or Taco Bell! :eek:
 
PhilGood said:
Most likely any build-up or contamination on a diaphragm is not some form of "metal oxide". If it were gold oxide it would be dark brownish red, and any other metal oxide collected would appear as a salt.
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First I've heard that gold can oxidize or tarnish. What can make that happen? Is it even possible in a normal environment? What were they doing with that microphone anyway?

This thread seems to have been an engineer (or wanna be engineer) making a pitch for a new design. Hey, I'm all for trying new materials and new approaches. It seems though that the arguments were being presented in a rather underhanded manner. How about titanium coating (which is lighter than gold, but heavier than aluminum) and filling the capsule with helium to change the speed of sound to compensate for it? Alternatively we could coat the thing in snake oil which does not tarnish unless you look at it.

browneyes, if you are pitching a new design or product - get to the pitch. Don't try to disguise it as education.
 
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gcolbert said:
How about titanium coating (which is lighter than gold, but heavier than aluminum) and filling the capsule with helium to change the speed of sound to compensate for it?
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Neumann and others already do titanium diaphragms in several expensive mics.

You can't use Helium at all as a capsule is not a sealed unit and air has to reach both sides of the diaphragm (even an omni has a pin-prick hole to equalise pressure to atmospheric pressure or the diaphragm would be destroyed as atmospheric pressure changes).



gcolbert said:
Alternatively we could coat the thing in snake oil which does not tarnish unless you look at it.
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Yes, this is the solution - I can sell you some for the very low price of £10,000 per fluid ounce. ;) :D :p
 
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