This is a follow on question from here: Simple Audio Amp for FPGA audio to PC in which I'm trying to get audio from an FPGA -> delta-sigma DAC -> op-amp -> Line Level.
Following the advice given in the above mentioned question, I've come up with this:
- Left side of circuit connects to 3.3V output pin on the FPGA
- The 3.3K and 4.7nf form a simple RC filter as part of the delta-sigma DAC
- The opamp is half of an opa2314
I've connected the RHS to microphone input on my PC and it records quite well, however...
I'd prefer to connect this to line-in. I've tried many different values for the two other resistors, including putting a 10K pot in for each, but can't seem to get enough gain for a line in signal.
Am I missing something, or am I simply hitting the limit of what this op-amp can do?