Question Regarding the Rectifer Tube

[tom241]

From what i have gatherd, all as the Rectifier Tube does is just convert AC power to DC? or maybe the other way around, anyway

how does this change the overall tone? changing from a tube to silicon diodes, or is this just a scam from mesa?

 

[wildrat666]

with the rectifier tubes engaged you get a more "saggy"" feeling to the tone. hard to describe. if youve heard an old fender then u know what i mean. it is not a scam from mesa.
with diode engaged you got a more direct tone, harder,
hope so´meone else can explain better