Dating marshall amps
The second prototype reportedly used two output transformers, two GZ34 rectifiers, and four 6L6 output tubes, whereas the third prototype used KT66 output tubes.
Ken Bran and Dudley Craven at Marshall eventually dropped the GZ34 tube rectifier, increasing power and reliability.
It probably used only one Radiospares Deluxe Output transformer, reportedly giving an output of 60 watt.
These amps run at much lower voltages than the later KT66 amps, producing less power while being easier on the tubes.
Also, it should be kept in mind that the voltages drop or sag significantly under load, since the power transformer was only rated for 200m A (by comparison, a Twin transformer is 450m A).
Jim suffered tuberculosis of the bones, and spent most of his school years in a plaster cast up to his arms.
Jim Marshall was born on July 29, 1923 in Kensington, England.