Beware of Plastic BM800's

[pmfalcman]

This is apparently the maker of that capsule; they do seem to claim it's actually a 4 micron aluminum foil diaphragm: "Perfect conbination of ribbon and condenser mic." !

https://www.aseyer.com/products/show/id/1.shtml

Seems metal foil capsules are their specialty. https://www.aseyer.com/custom/show/id/1.shtml

Great find!

Interesting microphones too. At least noisewise.

Now it's the question of getting the pricing

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It's Silvery Looking Diaphragm Condenser, obviously.

 

[MicMaven]

It does look that way, doesn't it?

The considrable temp difference I felt with the tio of my tongue must have been due to the huge difference in density between the thick brass housing and the 4 micron diaphragm.

YES - and perhaps for some other reason. I believe you said the diaphragm felt warmer than the brass outer ring. This empirical observation contradicts our expectations. Because the aluminum diaphragm has a much higher coefficient of heat exchange than the brass outer ring, we expect it to feel colder, not warmer than the brass ring. Check the chart here:

https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html

So, as the King in the play, says, "It is a puzzlement!"

Perhaps the capsule ring is not brass, but another metal or alloy which exchanges heat easier and faster than aluminum? OR, perhaps the aluminum felt warmer because there is an insulating spacer between the aluminum diaphragm and the rest of the capsule? Or ... shoot, for some other reason I cannot fathom. This one has me treed. (Although Mr. K Brown's original postulation about density remains viable.)

Sidebar: I am unsure what to think of licking the capsule, I mean . . . sheesh! . . . who knows? . . . and how do we dry it off afterward? . . . OK, never mind, I will try not to think about it!

So, considering curiosity killed the cat, I suppose I should stop trying to figure this out. James

 

[Khron]

Because the aluminum diaphragm has a much higher coefficient of heat exchange than the brass outer ring, we expect it to feel colder, not warmer than the brass ring.

Well yes, but there's also the (massive) difference in thermal mass...

 

[k brown]

I've also discovered that in the Tascam, Marantz, iSK, etc. mics that use this capsule, it seems most of the noise comes from the circuitry*; when hooked up to minimal electronics, the self noise of the capsule is amazingly low for such a small one.

The self-noise of the 36mm versions much be astonishingly low, especially the 2 micron one (L36B).
https://www.aseyer.com/products/show/id/2.shtml

I tend to pay little attention to manufacturers' noise figures; they all seem to have different ways of measuring (plus the published noise figures don't tell how much of the noise is from the capsule vs the circuitry).

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*I haven't traced out the circuits in these mics, but I have "KK12 v2" capsules in mics with three different electronics in them, and when I tried one with this little round board, it was (in a simple listening test) the least good of them all. Could be a great little board for DIY projects with electret capsules, if someone could figure out what's lacking in them (poor FET biasing, low quality parts, circuit design itself?.

 

[MicMaven]

Well yes, but there's also the (massive) difference in thermal mass...

YES. Agreed. My point is it cannot be fully explained by the typical or usual difference in the coefficient of exchange. I agree it is the difference in mass (thermal and physical and all that) which explains it. I hope my comment was not taken as a disagreement, just a sidebar observation.

No doubt it is a very nice sounding microphone for the very low price I paid (i.e., $29 incl shipping) and it has much more "body" in the sound than other, comparably priced microphones with the more typical capsule(s). I put mine back in the box until I decide where it fits in the larger collection.

Surely a sleeper! James

 

[Paul W]

Well yes, but there's also the (massive) difference in thermal mass...

And effective conductivity. An extremely thin layer of metal has a tiny cross section, and can't conduct much heat away from the part you're directly touching.

Metals only feel cool because they conduct heat away from you, and they can only do that if they have a significant cross section.

A very thin metal foil isn't going to be a good conductor of heat, even if it's marginally better than a sputtering of metal on mylar.

 

[k brown]

And effective conductivity. An extremely thin layer of metal has a tiny cross section, and can't conduct much heat away from the part you're directly touching.

Metals only feel cool because they conduct heat away from you, and they can only do that if they have a significant cross section.

A very thin metal foil isn't going to be a good conductor of heat, even if it's marginally better than a sputtering of metal on mylar.

I better keep my unscientific conclusion to myself from now on . . .

 

[k brown]

YES. Agreed. My point is it cannot be fully explained by the typical or usual difference in the coefficient of exchange. I agree it is the difference in mass (thermal and physical and all that) which explains it. I hope my comment was not taken as a disagreement, just a sidebar observation.

No doubt it is a very nice sounding microphone for the very low price I paid (i.e., $29 incl shipping) and it has much more "body" in the sound than other, comparably priced microphones with the more typical capsule(s). I put mine back in the box until I decide where it fits in the larger collection.

Surely a sleeper! James

It is a bit of a puzzle that these unique capsules have flown under the radar for nearly twenty years now.

I wonder if some of it is because companies all want to be able to describe their mics as having market-expected gold diaphragms.

 

[MicMaven]

I better keep my unscientific conclusion to myself from now on . . .

Nah. I believe you stand on solid ground. It believe Mr. Paul W concurs with your surmise it felt warmer because it has less thermal mass (per Mr. Khron) while Mr. Paul W supplies an enlightening gloss. Less thermal mass means it conveys less heat than the larger brass case, notwithstanding the difference in heat transfer coefficient. I think we are pretty much on the same page.

In any case, the discussion motivated me to revisit my example, which sounds pretty danged good for less than $30.

Mr. @k brown , what is required to remove the capsule from the saddle-ring-thing? Is it glued, screwed, or snapped in? Or ??? I wonder how it sounds in a Takstar CM-60 or similar pencil-type condenser body.

Sidebar - Judging from the photos, Mr. @pmfalcman has used his Marantz version fairly often, which seems a good indication of its utility.

Happy trails, y'all. James

 

[micolas]

I better keep my unscientific conclusion to myself from now on . . .

Don't do that!
A little brain-storming is needed for progress.
Unscientific approaches can often lead to unexpected ways of solving problems.
And besides, where would the joy of DIY be?