EH 1309B Memory Man
EH 1309B - Memory Man - 3 knobs - Black on gray box - Boost switch - SAD1024
1978 pots. Circuit board reads EH 1309B. The switch now wires directly to the board without "flying" components. That is the only obvious difference between 1309A and B that I have seen so far.
See EH 7500 for a schematic.