Do the math and check out that the AC30 has a common 50-ohm resistor biasing four EL84’s.
Even the schematic states that the voltage measurement at the cathodes should be 10VDC at quiescent and 12.5VDC at full output.
Another way of saying this is that the ‘maximum’ plate current is flowing at all times.
Non-Schumacher transformers – It’s been universally accepted that Fender only used Schumacher transformers on amps made in the 1960s and 1970s.
Used on the upper left corner of the grill cloth on most blackface era Fender amps. 4 1/2" wide, the "F" in the logo is about 2 1/2" inches tall.