Several of us here have a great deal of experience with that mic preamp topology.olafmatt wrote:2u2 film caps.mediatechnology wrote:So I understand correctly where you're headed with this what is the value range of C1 and C2 you propose?
Don't worry, your eyes are doing just fine, it's my schematic which is not showing a servo. I didn't draw the servo because there are so many ways to skin the cat. The idea was to have the servo monitor offset across Rg and then adjust the voltages at the opamps non-inverting inputs.JR. wrote:I don't see a servo in your schematic forwards or backwards.
The reason I didn't draw the servo and the way the voltages get controlled is that there are so many ways to do that and I wanted to avoid discussion about the not-so-important parts. Sorry, I guess I'm traumatized by other forms where people would have complaint that my opamps are not connected to the power supply when being presented the schematic linked in above...
The largest problem with putting your servo across Rg is that you will still have the full offset voltage of your servo op amp across Rg. At gains of 1000x, not uncommon for a mic preamp you will experience 1000x that DC offset at the gain stage output.