Polarity switch removed

[Echoes_of_Pompei]

Hi,

I have seen that some amps have the polarity switch removed.

Example here: https://hiwatt.org/RegAmps02.php

606 SA212 Hylight 4-input Used condition, but fully working. Polarity switch removed

What is the job of this switch and why it is removed sometimes?

Thank you

[mhuss]

A 'polarity' switch (on all old amplifiers, not just Hiwatts) was used in olden days, when two-wire/no ground mains connections were the norm, to minimize hum based on whatever sketchy mains outlet you were plugged into. Fender actually used one for a bit with 3-wire mains, but they mostly disappeared when 3-wire mains connection became the norm (and the law in most places ). It is fairly useless and even dangerous (if the internal cap fails) when using a modern 3-wire mains connection, with the ground lead connected to the amp chassis.

[Echoes_of_Pompei]

Good to know. Thank you Mark!