Probably right. Some radios have a couple taps on primary of the power transformer. Selecting a higher input voltage tap will reduce all voltages going into your radio. If you have 115 input voltage and select a tap for 125 this will reduce voltage to your radio around 8%.
Norm
:Hello, I have a huge separate power supply in a separate metal case on the shelf below in this console radio. It has a switch that says "to prolong tube life, keep this switch in the low position. What does this switch do? I would think it reduces either voltage to the filaments or b+