The microphone capsule photo and information thread

[pasarski]

Thanks, good news.

You don't have by any chance AOM 5024 or Primo EM 272 based mics to compare to?

The published S/N is not that great

No I have not tried those. I don't ever look the Ali specs, they are probably written by chatGPT My OPIC ( I call it Rogsophone) is so quiet that the preamp noise dominates.

 

[pmfalcman]

the Ali specs, they are probably written by chatGPT

You're too optimistic
BTW - I only trust these if they're bad.
And for this capsule S/N is 72 dB(A).

Sometime ago I happened there upon a SDC mic that's specced at S/N = 94 dB....
Somehow I do not believe this number.
But it's a great looking mic, tbh.

My OPIC ( I call it Rogsophone) is so quiet that the preamp noise dominates.

Hmmm.... It may mean that you have a lousy preamp
Just kidding. This is great news. Thank you!

Nb.: for some time I "walk around" OPIC thinking of building a pair

 

[pasarski]

Hmmm.... It may mean that you have a lousy preamp
Just kidding. This is great news. Thank you!

Actually the preamp has wonderful published noise spec of "Equivalent Input Noise@A-wt,150 Ohm | -130.5dBu" but of course it's a manufacturer's number so who knows?

 

[TimG]

The Mighty Rode NTK thanks to head basket fail.

 

[thomasdf]

I was doing some cleaning in my studio and thought I’d share some picture of a pretty rare Oktava microphone, the МКЭ-7. I have a matched pair and the paper manuals with all the infos, graphs etc. Beautiful !
Supposedly an Omni electret but it looks like an Omni SDC to me ?
Shame I haven’t use them a lot because they sounded a bit thin / harsh. I also never recapped them or opened until now. Maybe they sound better without the aluminium grid. I’d have to do some testing.

I am sure you capsule gurus will have clever insight to share

 

[Khron]

Supposedly an Omni electret but it looks like an Omni SDC to me ?

No bias voltage applied to the capsule, and why can't an electret have a "small diaphragm"?

 

[rock soderstrom]

No bias voltage applied to the capsule

It does, the capsule receives an external polarization voltage via R1 from the R2/R3 node. This is a source follower, very similar to the cathode follower in my current “The Electron” project.

 

[bremusound]

I don‘t think it‘s an omni capsule tbh. Frequency response doesn‘t fit and the lower part of the capsule construction would make no sense.

 

[thomasdf]

Well maybe I'm completely wrong ! I'll Google translate the manual and will report back

edit : unidirectionnal electret indeed !

 

[hop.sing]

The official frequency response looks like it is tailored for a close distance speech microphone. Looks a little bit like the one from the Schoeps mk40 capsule.

 

[kingkorg]

I was doing some cleaning in my studio and thought I’d share some picture of a pretty rare Oktava microphone, the МКЭ-7. I have a matched pair and the paper manuals with all the infos, graphs etc. Beautiful !
Supposedly an Omni electret but it looks like an Omni SDC to me ?
Shame I haven’t use them a lot because they sounded a bit thin / harsh. I also never recapped them or opened until now. Maybe they sound better without the aluminium grid. I’d have to do some testing.

I am sure you capsule gurus will have clever insight to share

That capsule is excellent copy of KM84 capsule, with accurate backplate. It should be a cardioid, but could be it is tuned differently for that model. The grid can't be removed, and is not cause of the issue.

Random advice to mic enthusiasts:

Stop obsessing with grilles, and various stuff in front of diaphragms. As long as they don't cover more than 50% of the diaphragm surface, and are not more than half the audible wavelength away from the diaphragm they can't affect the frequency response according to the laws of physics. According to the laws of online mic gurus they make all the diference. YMMV.

 

[thomasdf]

Ah, I knew it looked familiar. I'll recap one of these badboys and will test it in proper condition. I am affraid the flat black part of the body will cause some weird rear reflection. Maybe that's taken into account ! It's never been clear if they run on 48V or 12V ... I ran them at 12V, maybe that's why they didn't sound that great back when I tested them years ago... oops.

Regarding the grille, I was reffering to the LARGE one, which is more of a headbasket. It is fitted on the first picture, and I removed it to access the capsule, on the later pictures.

 

[kingkorg]

Regarding the grille, I was reffering to the LARGE one, which is more of a headbasket. It is fitted on the first picture, and I removed it to access the capsule, on the later pictures

Ok that makes more sense, however i was saying more in general.

 

[pmfalcman]

Maybe that's taken into account ! It's never been clear if they run on 48V or 12V ... I ran them at 12V, maybe that's why they didn't sound that great back when I tested them years ago... oops.

What seems like (XLR?) connector description reads:
(pin) 1: +10 V, output
(pin) 2: ground
(pin) 3: +10V, output

At least it looks like badly scribbled + in front of 10V at the (pin) 1
More like a + than a --

["B" stands for "W" like "wolts", in cyrilic.]