Possible Mod For VOX AC30CC1

[zozoe]

Hi all~ I have this very cool AC30 1x12 combo from the late '90s or early 2000s, & it has these switchable bias options, 50 or 82, where the 82 offers a slightly lower output, 22w before distortion, and I'm curious to know if I could have many tech make it higher than the 82 setting & expect even earlier breakup? I'd need to find a schematic, but is this even possible & safe with the proper value changes?
Many thanks in advance.

[vintagekiki]

The values 50 and 82 refer to the value of the resistor in the cathode 4xEL84.
With Rk = 50 the cathode current for 4xEL84 reaches a value of 220mA, with amp power of 30W. This is the maximum value that 4xEL84 can withstand.
With Rk = 82 the cathode current for 4xEL84 reaches a value of 150mA, with slightly less amp power.

Increasing the Rk to a value greater than 82 Ohm, a lower cathode current is obtained, the amp power is lower, but the character of the tone changes noticeably (degrades).
Solution is in modify wiring the cathode connection, so that the amp can work with 2xEL84 (power as AC15) or with 4xEL84 (power as AC30)

1)
https://el34world.com/Forum/index.php?topic=18878.0
Half power switch question


2)
http://dealers.korgusa.com/svcfiles/AC30HW2.pdf

3)
http://dealers.korgusa.com/svcfiles/AC30HH_Smanual.pdf