Ja tu razliku između pentodnog u odnosu na triodni mod ( na stranu duple razlike u snazi ) doživljavam upravo ovako kao je napisao član @Billm sa The Gear Page foruma ( forum za muzičare ).
https://www.thegearpage.net/board/index.php?threads/triode-vs-pentode-mode.647871/
" It's an inexpensive way for manufacturers to add a feature to an amp and to make a somewhat different tone available.
Your output tubes are typically pentodes, meaning that they have five elements inside (plate, cathode, control grid, screen grid, suppressor grid). Pentodes (and beam power tetrodes, such as the 6L6/6V6 family) are very efficient... as tubes go. The screen grid eliminates the capacitance between the plate and the control grid, which makes the tube more linear and controls electron flow more accurately, for more power.
Connecting the screen grid directly to the plate supply (same voltage as the plate) makes the tube function more like a triode, hence the name. It almost halves the maximum power, so people sometimes call it a half-power switch. The tube wastes power in triode mode.
At anything less than full volume, the difference between full and half power is not that noticeable. It definitely does not halve the loudness of the amp.
Triode mode on a pentode sounds thicker, mushier, less articulate. Some people think it sounds more bluesy; I think it just sounds sloppy, like the difference between sober and drunk. "