This amplifier with 4 tubes at the output and direct connection to the power grid (power supply without transformer) was found in documentation from 1939. Note the connection of tubes in parallel at the output, a technique used to obtain more power.

This amplifier with 4 tubes at the output and direct connection to the power grid (power supply without transformer) was found in documentation from 1939. Note the connection of tubes in parallel at the output, a technique used to obtain more power.