I'm trying to design an unbalanced line input for an audio device using a single supply. I would like the input stage to provide variable gain between 0 and 2.
This is what I have come up with so far:
I have been running some basic simulations in LTspice that suggest the circuit is working as intended, so I hope I'm not too far off the mark.
However, I'm uncertain about a couple of things:
- Am I correct in assuming that the input impedance of the circuit equals GAIN + R4 (i.e 14.7K)?
- How do I calculate appropriate values for R1 and R2? 10K is just a guess...