July 20, 2009, 5:57 a.m.
Another Microphone project I tried recently was reviving an old generic dynamic mic that had gone dead. I opened it up and removed the dynamic capsule, the circuit that went along with it, and the internal windscreen. I left the wires that connected the to the three pin XLR jack at the bottom of the mic. After some research, I decided to go with a very simple circuit to operate from 48V phantom power for my first attempt. The circuit consists of a cheap electret condenser element (around 3 bucks at radio shack), connected in series with a 47kOhm resistor, the "hot" wire(connected to pin 1) goes the the resistor, which is connected to the positive side (red wire in the picture to the above). The ground of the mic element(bare wire) was connected to pin three, and the negative output of the capsule(white wire) was connected to pin two. Then, I went to short pins two and three together, but that had already been done on the microphone body I was using.
The mic sounds pretty decent for how simple the circuit was, the circuit is just as usable as any cheap used dynamic would be, captures more of the high, but seems pretty weak in the mids, while the cheap dynamics seem to be heavy on the low mids and sound muffled. Below are three acoustic guitar recordings to give you an idea of the sound of the mic in context to others. Mic placement: 12 inches off guitar bridge Signal chain: Mic->DIGI 003->.wav->.mp3 (unfortunate, but necessary to save space) Mics used: DIY One Resistor Condenser, Budget Crate Dynamic Vocal, Modded MXL 990
MXL 990 Mod