Where are detailed plans of the akg c12 microphone and explainations of this circuit?

[CaptainCapsule]

I am currently interested in tube microphones such as the AKG C12. In principle, the circuit is less complicated than most tube amplifiers in my opinion, but unlike tube amplifiers, there are almost no public explanations of the circuit diagrams for tube microphones and no circuit diagrams with marked target voltages. Where can I find explanations of this circuit and circuit diagrams with marked target voltages? It is also difficult to find all the components such as the power transformer using the circuit diagram, because instead of voltages, only a model name of the transformer is entered in the circuit diagram. What I also don't understand is why the anode, cathode, grid and heater are connected to the second triode of the tube. Is a double triode installed, but only one triode is actually used? If so, why is that?

I look forward to your help!

 

[rock soderstrom]

I am currently interested in tube microphones such as the AKG C12. In principle, the circuit is less complicated than most tube amplifiers in my opinion, but unlike tube amplifiers, there are almost no public explanations of the circuit diagrams for tube microphones and no circuit diagrams with marked target voltages.

Hi, there is a lot of information about this microphone on the WWW and especially here on groupdiy.com. The search engine here is very powerful, read up on it, especially this thread here will answer almost all your questions. Admittedly, that's quite a lot to read...

You ask in your first post:

For example its not clear to me why anode, kathode, heater and grid ist connected on the second triode.

This is simply due to the fact that we only use one triode system of the tube, so the second triode system is grounded so that there are no problems whatsoever occur.

there are almost no public explanations of the circuit diagrams for tube microphones and no circuit diagrams with marked target voltages.

See the linked thread and the original schematics.

It is also difficult to find all the components such as the power transformer using the circuit diagram, because instead of voltages, only a model name of the transformer is entered in the circuit diagram.

This is basic knowledge if you want to build a power supply safely. You also need some ohms law and then you adapt your transformer and the whole power supply to the required conditions. In my opinion, you should have these skills if you want to work with potentially life-threatening voltages. You can also modify existing power supplies from other manufacturers (e.g. Thomann). But again, don't kill yourself, you are still working with mains voltage, it takes no prisoners.

What I also don't understand is why the anode, cathode, grid and heater are connected to the second triode of the tube. Is a double triode installed, but only one triode is actually used? If so, why is that?

As described above, the impedance converter in the microphone only requires one triode system, the other is not needed and is therefore grounded.

Enjoy reading and good luck with your microphone project. Work safely and stay healthy.

 

[Khron]

Is a double triode installed, but only one triode is actually used?

Yes.

If so, why is that?

Ubiquity of the 6072 / 12A_7 / ECC8x dual triodes. Pretty sure there were a lot easier (and cheaper) to source (and sort through & pick the lower-noise ones) than more "esoteric" ones like AC701K etc.

there are almost no public explanations of the circuit diagrams for tube microphones and no circuit diagrams with marked target voltages

Why should there be? And/or, especially since

In principle, the circuit is less complicated than most tube amplifiers

just what sort of "explanations" might you be expecting? A single triode gain-stage, plate output through a capacitor into a transformer. The more unusual thing is the way the slightly-negative grid bias is achieved, in order to be able to ground the cathode, but other than that... 🤷‍♂️

PS: I see @rock soderstrom was quicker on the trigger 😁

 

[CaptainCapsule]

Hi, there is a lot of information about this microphone on the WWW and especially here on groupdiy.com. The search engine here is very powerful, read up on it, especially this thread here will answer almost all your questions. Admittedly, that's quite a lot to read...

You ask in your first post:

This is simply due to the fact that we only use one triode system of the tube, so the second triode system is grounded so that there are no problems whatsoever occur.

See the linked thread and the original schematics.

This is basic knowledge if you want to build a power supply safely. You also need some ohms law and then you adapt your transformer and the whole power supply to the required conditions. In my opinion, you should have these skills if you want to work with potentially life-threatening voltages. You can also modify existing power supplies from other manufacturers (e.g. Thomann). But again, don't kill yourself, you are still working with mains voltage, it takes no prisoners.

As described above, the impedance converter in the microphone only requires one triode system, the other is not needed and is therefore grounded.

Enjoy reading and good luck with your microphone project. Work safely and stay healthy.

I have basic knowledge about power electronics and know how not to instant kill myself. Yes there are lot of information, but most are building tutorials. Where do I find a schematics with the target voltages to trouble shoot a C12 microphone if I build it without PCB. And where do I find explainations of this circuit? For guitar tube amps there are many great tutorials like from Rob Robinette?

 

[rock soderstrom]

You are welcome!