DIY Impedance Control; Condenser Mic

[ashcat_lt]

…between pins 2 and 3 and each pin has an identical voltage…

Youre right of course. Sorry bout that.

 

[gianluca68]

Those devices put a resistor between pin 2 and pin 3, raising the load to the microphone. Since a dynamic mic is like a dinamo, it has some electro-mechanical effects, braking the moving diaphragm. Then you obtain some differences in sound, i.e. a reduced sensitivity to handling noise and an attenuation of low frequencies, because the microphone has an inductive output.

 

[drtechno]

Hi there, new to the forums, how's it going? I was hoping somebody might be able to answer this basic audio question for me:

I've seen some simple designs for a DIY variable impedance control for your microphones which is comprised of some XLR sockets, a potentiometer and some connecting wires. I like the thought of making one myself, just for fun, but I want something that will work with a condenser mic which obviously requires phantom power. I currently have a mixer powering my mic, but would this same design work if I were to use an external phantom power supply before it such that the signal chain goes as follows:

Mic > Phantom Power Supply > Impedance Control > Mixer

Thank you.

I guess someone found my 'dynamic mic cords' in a studio somewhere and opened them up and found my 470 or 1K ohm resistor tied across 2&3.
This mod was made decades ago because of the lack of termination on dynamic mics with long runs caused high frequency loss. Terminating the end causes the wire to run in transmission line mode and lowers the loss.
Condenser mics, regardless if they are transformer out or capacitor coupled, are terminated so any excess noise or poor gain from them is caused by the termination at both ends are unequal. So the solution is to either modify the mic or mic preamp termination circuit. Some mic preamps have a "variable input impedance" on them which just change the resistance of the termination section of the coupling circuit. This mod is doing the same thing, just on the mic end. I would just mod the condenser mic to the nominal impedance the preamp wants, or replace the mic with one that will work better with that preamp.