This is a modified version of the circuit on Rob Rowlette's Classic and Vintage Circuits Web Site. My Modification keeps a constant 5k load on the secondary of the input transformer and simplifies the switching to a 2-bank switch. (Note that the three bank circuit on Robs page changes load for 5k to 12k about half way through the switching steps because of a missing 12k resistor across the input transformer secondary which the real 1066, 1073, 1078 had fitted. These modules used a 3-bank switch due to an extra preamp stage and a line switching section as well. Loading transformers properly is a big part the Neve sound.