With 300 uV in, what is the highest p-p voltage seen at the top of the output pot?
Am also considering a balanced mike input for some equipment.
Thanks
Phil
In my current setup the OP pot is about 70% giving just the right level to drive the 1124DSP EQ to just below clip with a RE-27 mic, so about 500MV at the top of the pot. Several ways to increase the gain if needed. Increase the two 47K Rs to say 68K or more. Increase the mic gain trim pot to say 50K or more. Modify the OP buffer op amp by adding a R from pin 9 to Gnd and a feedback R from 8 to 9 and play with the ratio. Best to assemble it on an experimenters plug board (without the IP RF filters) and play with it. The low cost OP transformer does roll off the lows about 3DB per octave starting at 200HZ but I needed about 7db attenuation down there anyway so it is not a problem. It does work very well as presented for my particular application.
Have also been playing with different EQ profiles using all 12 filters and have achieved close to a brick wall low pass response starting at 3.7khz dropping like a stone above that. Sure keeps the BW respectable in a PW mod TX.
73s Nigel