maybe a retard question, but.....

IV owner here for about 5 years now. Love the amp, read the manual a number of times, but still dont quite understand a few things.

When I flip from Pentode - Triode, I notice a slight difference manily in volume.

Mid Gain - Harmonics, I can noticed the mid-gain boost.

Class A - SimulClass - Obviously, A is 2 power tubes, Simul is all 4.

I also dont notice a whole heck of a difference when running Tweed vs. Full Power.

what are the main functions of Pentod/Triode, Tweed and Full?

bryan_kilco said:

IV owner here for about 5 years now. Love the amp, read the manual a number of times, but still dont quite understand a few things.

When I flip from Pentode - Triode, I notice a slight difference manily in volume.

Mid Gain - Harmonics, I can noticed the mid-gain boost.

Class A - SimulClass - Obviously, A is 2 power tubes, Simul is all 4.

I also dont notice a whole heck of a difference when running Tweed vs. Full Power.

what are the main functions of Pentod/Triode, Tweed and Full?

Click to expand...

Pentode is about 15 watts ( 30 watts) louder than triode and has more attack and can seem to have more treble.
Triode ( 15 Watts) is a less efficient way to run the tubes with a side effect of less power, but smoother tone. Randall Smith
states it's like using your thumb instead of a pick. A rounder tone is derived. Tweed, is a a power transformer primary tap that acts like a variac. It reduced all internal
voltages to make the amp behave differently. With lower voltages, the amp has smoother tone, less power and altered harmonics. Randall Smith has been quoted
seeing EVH lower his Marshalls with a variac to about 85-90 volts at the primary, hence the browner tone or a brown out effect. At higher volume in tweed you should notice a squishier, smoother treble tone and less attack. In full power, the amp will be tighter, sharper in treble and louder. The Mid-Gain is just adding a cap on the V2 that increases the gain about 6db. Like on the C+, there is no cap there, but the MK IV uses this position to add a cap for gain in the R2 as well. A 15uf cap is added for the R2 to add gain and a thick tone. It's switched out for the clean and lead channels. The Mid-Gain is manually adding a 2.2uf cap for the 6db of gain to the lead channel and the lower value cap has more flavoring in midrange and treble. The Harmonics side is basically the normal way the amp sounds without added the Mid-Gain cap.