27-11-2016, 02:44 PM
In light of your most recent reply, I've chopped away most of what I typed. However, this is worth leaving:
Well, Kalee's feedback network isn't all that different to a single resistor. I think of it as a single resistor that has a different value at different frequencies
Perhaps this shows that you are thinking in terms of DC when considering a virtual earth circuit. And that's almost certainly because op-amp circuits always work down to DC. But here, we have to consider that the DC conditions are quite separate to the AC signal conditions.
So yes, at DC, it is not a virtual earth. But at AC, it is.
(27-11-2016, 02:18 PM)Murphyv310 Wrote: In Kalee's amp the fact he has put an RC network into the circuit will only effect the AC conditions of the amp giving different amounts of feedback at certain frequencies for the purposes of RIAA Equalisation, so in effect how can you call this a true virtual earth circuit.
Well, Kalee's feedback network isn't all that different to a single resistor. I think of it as a single resistor that has a different value at different frequencies
Perhaps this shows that you are thinking in terms of DC when considering a virtual earth circuit. And that's almost certainly because op-amp circuits always work down to DC. But here, we have to consider that the DC conditions are quite separate to the AC signal conditions.
So yes, at DC, it is not a virtual earth. But at AC, it is.
