Creation CK12 capsule and power supply question

[Putchy]

Hello,

For a student project I chose to build a condenser microphone. For the capsule, I took inspiration from a CK-12, which was the least difficult to make. So I machined it from brass in x2 scale. For the membrane, I chose aluminum mylar (the only one I could find).

Now that I've got the model, I need to make it work. And that's where my knowledge ends. I know I need to use a Phantom power supply, but I don't know which one (voltage and current), given that my capsule is twice the size of the normal one. As for the electronic wiring, I have very little precise documentation.

I know that with my capsule I might not get the audible frequencies, but that's okay, as long as I get a response to a signal I'll be happy.

Information about the capsule :
- S = 1260 mm² (area of the membrane)
- Cmeasurement = 101.6 pF
The only value I can modify is the spacing between the diaphragm and the backplate. At the moment it's 80 μm, but I'm thinking of reducing it to 40μm.

If you can help me with any information (documentation or diagram) I'd be grateful.
I'm always open to help.
Sorry if my English isn't good, I'm still learning.

 

[pasarski]

Wow, respect! You started making mics other way around than usual. Capsule is the most difficult part. And CK12 is the most difficult capsule to make, at least if you want it to sound good. But yeah I understand that that's not the point of this project.

You need an enclosure and an impedance converter for the capsule. Lot's of information here if you do the search.

 

[Putchy]

Wow, respect! You started making mics other way around than usual. Capsule is the most difficult part. And CK12 is the most difficult capsule to make, at least if you want it to sound good. But yeah I understand that that's not the point of this project.

You need an enclosure and an impedance converter for the capsule. Lot's of information here if you do the search.

Thanks, I know it's not going to be easy but I like a challenge.
In this case I'll try to find a simplistic impedance converter schematic.

 

[OneRoomStudio]

You're probably going to have to arrive at the right values through experimentation. If I were you, I'd try polarizing it with something around 60V to start, and see what that gets you. The current will be negligible (<1mA). Make sure you keep the high impedances in mind when you're building up your circuit, and keep it simple.

Regular CK12's are around 80pF, so 100pF isn't far off.

 

[Tim Campbell]

Please show us your delay network. To begin with you can simply polarize it using 48v phantom power. That's what Haun and AKG did on some of their models

 

[Khron]

I could be wrong though, but that looks to me a lot more like the Chinese edge-terminated K67's..? Rather than the dozen-component CK12...

 

[soapfoot]

I suggest doing what many young engineers do--investigate prior work done by others, copy it, and then make your own refinements.

Do a search on this forum for terms like "schoeps circuit" "transformerless" or "active-balanced" condenser microphone circuits. Choose a simple one, build it, and analyze the schematic. Try to isolate different functional sections or 'building blocks' of those circuits and see where you can make adjustments to optimize performance.

Good luck!

 

[Recording Engineer]

I could be wrong though, but that looks to me a lot more like the Chinese edge-terminated K67's..? Rather than the dozen-component CK12...

I had pretty-well assumed that when I saw the picture. Didn’t say anything though. Great DIY regardless!

 

[Putchy]

Thank you for your many replies.
In this case, I will try to find a 48V power supply, otherwise I will try with a 12V hex inverter circuit to obtain a voltage of 80V and maybe the preamplifier that goes with it.

 

[Tim Campbell]

Well you can easily find stand alone phantom power supplies but every mixer supplies 48v phantom