Making a LDC Capsule - Videos

[RJ]

Among others inspired by the content shared in this forum I had a go on a capsule of my own design these resent days. I felt obliged to show you the results. I guess the capsule is omni directional as far as my understanding goes. The concept is reduced to its very basics so that it is feasible with my limited machining skills and tools. It works and sounds more or less reasonable. But pared with the t-bone electronics it still lacks sensitivity. If someone is interested in details feel free to ask! And if someone wants to point out flaws (which there surely are...) please do so as well!

RJ

 

[kingkorg]

 

[Whoops]

Great stuff RJ, congratulations

How have you done the diaphragms? which materials did you use?

 

[Whoops]

Klaus Heyne,
Diaphragm Tunning method - "You Ping it"

from:
https://www.prosoundweb.com/interview-klaus-heyne-master-of-microphone-modifications/5/______________________________________________________________________________________

KH: Then I fine-tune the capsule, physically yank it out and using a torque screwdriver, adjust the distance from the diaphragm to the backplate and maybe even adjust the two backplates together. There are basically four parts to this sandwich: diaphragm, backplate, backplate, diaphragm. How these are put together determines midrange behavior, and also determines high and low frequency behavior.


So you have, within a certain range, some tolerance for discretionary adjustment. I can either tighten or slacken a little bit. Or I may take a diaphragm off and try another diaphragm, one with a different resonance frequency. I know from experience how a certain resonance frequency translates into upper midrange behavior.


BB: How do you know what that resonance frequency is?


KH: Very simple. I ping it. And I use a tuning fork. So if it sounds forward in the upper mids, and the resonance of the diaphragm is in the region of D sharp or E, I would say I could not do what I need to do by torquing the screws. I will need another diaphragm.


BB: That’s surprising! How broad is the range of resonance frequencies?


KH: It can be six or seven half tones, quite a bit. And you can’t control it much better than that. All of these go into ovens, that’s how they tension them. There’s still so much art, so much luck, in diaphragm manufacture. To a “t”, almost every capsule mimics something Neumann did in the late fifties. Look at any German or Chinese microphone, and you will find they all use the same basic principle.

____________________________________________________________________________________

 

[kingkorg]

I would pretty much delete that post and not contribute any more to the misleading content this man has created. Not that he isn't knowledgeable, it's just that he pretty much never shared anything useful. Just noise and smoke, no one will ever recreate magic of german mics, hearing phase shift in capacitors while speaking into a mic, harshness, harshness, harshness.

 

[soliloqueen]

I just listen to the diaphragm tension "on the way up." If you're using a threaded tuning jig and you're going fast enough you can hear it like dragging your finger up the fretboard of a guitar. No need to ping it, you can just stop when it gets to the right place. I've never heard of anyone else doing it this way, that's just how I do it. You can hear it happen at 1:40 of the soyuz capsule tour part 2 in the op

You can't absolutely know the tension of the diaphragm by doing it that way because the tension changes when you clamp the ring down because it changes the effective size of the resonant body but you can know in general the ratio between two different tunings by their tunings before the clamping. It just takes some trial and error so that you know what unclamped pitch correlates with what shape of capsule measurement.

 

[LevinGuitar]

Hello everyone and Happy New Year!
In the Soviet Union (and now too) there was a copy of the KM 84 capsule - this is the Octava MKE-2 microphone (cardioid). There was also a microphone with a omni directional - MKE-10.
These microphones were microphones with a very soft upper frequency range.
There was also a version of the microphone on a vacuum tube - "Octava MK-12".

The "E" from "MKE" means electret, can that backlate be used for a externally polarized capsule?

 

[Sonic]

The "E" from "MKE" means electret, can that backlate be used for a externally polarized capsule?

LevinGuitar​

yes, E is electret. These capsules hold the electret charge well even decades later. But, if necessary, you can connect external polarization. I did that.
In MKE-2, electret is applied to the membrane itself.

 

[Whoops]

I would pretty much delete that post and not contribute any more to the misleading content this man has created. Not that he isn't knowledgeable, it's just that he pretty much never shared anything useful. Just noise and smoke, no one will ever recreate magic of german mics, hearing phase shift in capacitors while speaking into a mic, harshness, harshness, harshness.

The post was a joke, it's supposed to be funny. I laugh a lot when reading some of his stuff.

I completely agree with you on this man but humor is also part of life

 

[kingkorg]

You totally got me there!
Posts like that got me into modding capsules, so i owe him some gratitude. However i am sure i lost something like a year doing research, going through his articles, trying to make sense of anything he was saying. At a point i started doubting my own sanity.

 

[Whoops]

Oh mate,
he decides that a specific brand of cable is good for a mic because it sounds "more sexy" than the other.
I didn't know him, but I was reading his thread on the U67 vintage Vs the Reissue and I was not believing it, it seemed a litle bit crazy at some point. The arguments and reasons he gives to declare something sounds better than other is a comedy in itself.

I'm pretty sure he is very knowledge and experienced with Neumann microphones but I don't trust his judgment and opinions on sound a single bit.

 

[Tim Campbell]

One of my very first series of capsules. An aluminum backplate K67 with foil from a capacitor for memebranes built in I believe 2001-2002.

 

[Whoops]

One of my very first series of capsules. An aluminum backplate K67 with foil from a capacitor for memebranes built in I believe 2001-2002.

Very nice Tim,
thanks for sharing.

How does it sound?

 

[Tim Campbell]

I was surprised . It sounded very much like the K67 I copied it after. That's why I switched to other designs because they were more difficult. This pic is from that period. The capsule is buried somewhere among other projects. You can see from the schematic it's on a 1st generation G7. The schematic says 1999 so the capsule could be a bit earlier.

The mount holding the capsule is made from an eraser and I learned to manipulate silicone to make the large wedge under that.

 

[soliloqueen]

I was surprised . It sounded very much like the K67 I copied it after. That's why I switched to other designs because they were more difficult. This pic is from that period. The capsule is buried somewhere among other projects. You can see from the schematic it's on a 1st generation G7. The schematic says 1999 so the capsule could be a bit earlier.

The mount holding the capsule is made from an eraser and I learned to manipulate silicone to make the large wedge under that.

Yeah, my personal observations have been that being easy to copy is kind of the point of the k67. Ease of production is the whole reason it was invented over the k47. The hole pattern is just an equally spaced 12x12 grid with the ones that don't fit inside the area on the backplate deleted. It's designed to be super simple to machine by moving in straight lines, easy to program in CNC, etc. Compared to a medium difficulty capsule like the k47 or a hard capsule like the ck12, it's not much. It can really only be messed up by mylar or tension issues or lack of adequate flatness.

 

[Murdock]

Thanks alot for all the contributions and informative posts!
I hope I don't hijack the thread with my question. If inappropriate please tell me so I open another thread.

I have two old 28,5mm Rojac omni capsules with springloaded tension rings and one of them has a ripped diaphragm.
Does anyone have some tips on which diaphragm thickness I should use?
I have some 5 and 10 micron aluminised mylar film and normal mylar in the same thickness as spacers.
I also thought about using sub 1 micron pure aluminium film.
And how do I know how high I can polarize the backplate? What dictates the possible polarisation voltage?
I read that omni capsules need a rather high tension and some have also higher polarisation voltage.
Would be glad about any tips!

 

[Tim Campbell]

Use the 5 micron. The polarization voltage / distance to backplate is only limited to collapsing. If your backplae is flat and the backplate, the membrane are clean and there are no dust particles trapped then your polarization voltage should be set so that the membrane does not stick to the backplate when you pop your "P's" You want the output of the capsule to be strong enough so that you don't have to use excessive preamp gain adding noise.

 

[Murdock]

Hey Tim, thanks for your input!
Can you see if I need a spacer between backplate and diaphragm? Or is the spacing kind of set with the distance of the tension ring and the backplate?

 

[Tim Campbell]

I have no idea. I don't know that capsule but vintage Neumann capsules had their distance set by the machining. The best way to find out is trial and error.

Stretch a piece of mylar over the backplate. If the capacitance is higher than 90pf between them you need a spacer.

For this type capsule 50pf is probably a better capacitance but it depends on your polarization voltage.

 

[Murdock]

Thanks Tim!
One last question.
I just checked the capsule and it seems the backplate portrudes over the tension ring. So I would need an isolator, right? Would I have to place a clear mylar film under the diaphragm in the tension Ring to isolate the diaphragm from the backplate and act as the spacer at the same Time?
But then the diaphragm could not move because it would be stretched over the backplate right?