> I have a Bogen Challenger CHA 75A Pa amplifier dated 1974, I need a
> schematic, ive found the schem. for the CHA 75 but not 75A, it has 2
> power tubes instead of 4 like the 75. Im a guitar amp builder and this
> thing just baffles me. Id like to change the preamp to a more guitar
> friendly layout, 5f6 or 5e3, but the power section is crazy on this
> thing. Any help would be greatly appreciated. thanks in advance.
found out 75 and 75a are same amp just different tubes. thanks