I had Brown Dog/Cimarron make me some OPA1612 to DIP adapters to try in the Flat Moving Magnet Preamp board.
I wanted to see how the OPA1612 worked both as a moving magnet preamp as well as a moving coil application in the balanced instrumentation amp configuration here:
A Flat Balanced Input/Balanced Output Moving Magnet Phono Preamp
The moving magnet performance was not optimal due to the higher current noise of the OPA1612 compared to the NJM2068, NJM2114, NJM5532 and OPA2134.
The results were not a big surprise.
As a moving coil preamp the OPA1612 turns out to be pretty decent.
I modified the resistor values to lower noise making Rg 5 Ohms (total) and Rfb 499R X2.
R4 and R5 were made 0R; R2 and R3 were 499R.
The single-ended output gain is 46 dB.
Rsource was 10R. Cterm 0.
The measurement bandwidth was 20 kHz.
OPA1612 Moving Coil Preamp 46dB Gain 10R Source
The blue trace is the output of the preamp after the THAT1240 common mode rejection stage.
The red trace is the converter residual noise.
The ein looks to be about -131 dBu, 218 nV.
The noise density is about 1.5 nV/sqrtHz.
Though not sub-nV pretty decent for an un-assisted op amp.
The OPA1612 has respectable performance in this circuit as a moving coil preamp.