It is easy to cobble together projects these days. ICs make it simple and microcontrollers even easier. However, we always respect a project that really goes from concept to finished product and that’s what we liked about [Curt Yengst’s] “THAT” Thing microphone preamp.
In part 1 of his post about it, he talks about the basic ideas including the chips from THAT — a small but high-end audio chipmaker — he uses. The first chip is a low-noise audio preamp and the other is a balanced line driver.
In part 2, we get to see [Curt] go from breadboard testing to PCB fabrication all the way to the finished rack-mounted device with a good looking front panel. It worked, but like all designers, [Curt] was already thinking about the next version.
In fact, version two uses an input transformer and replaces the gain pot with a switch that can select fixed gains. This apparently allows the gain components to match better on the left and right channels since you can easily use precise resistor values instead of hoping that two pots sync up properly.
The end result looks pretty professional. We have seen a wide variety of microphone preamps in the past. Of course, some preamps connect to record players, not microphones.