So, i'm a n00b with tube amps, and playing around with the line 6 edit, i'm not really learning or hearing any significant changes as i mess around with these features:
whats class a vs class a/b
topology (I- IV)
tri vs pent mode
And more specifically, what effect does the setting have on tone?
Here's an example for the DT50 that explains then.
Nutshell: Class A/B is the power amp model mode, tri/pent is the power tube mode, topology is the preamp mode. For example, if you buy a mesa Roadster, each channel has 3 modes (modern, vintage, brit, fat, etc). So something like the Treadplate model (which iirc is a mark 4) has the 4 Marks in it for preamp modeling.Operating class (Class A/Class AB) and power tube mode (Pentode/Triode).
Class A - Switched to Class A, DT50 runs at 25 watts and is cathode biased. The feel is open and dynamic with greater touch sensitivity.
Class AB - Switched to Class AB, DT50 runs at 50 watts and is fixed biased. This produces a tighter feel with more headroom, which is perfect for louder clean tones.
POWER TUBE MODE
Pentode - Big, loud and clear for commanding tones.
Triode - Quieter, rounder and darker with a more vintage-style sound.
The other NFL characteristics, there is some info in the descriptions below that can help you understand what they sound like a little bit:
Voicing I: American clean. High amount of negative feedback for a tight sound that’s reminiscent of 60s-style American cleans.
Voicing II: English crunch. Medium amount of negative feedback for a looser tone that echoes classic English breakup.
Voicing III: English chime. Zero negative feedback for an open, dynamic feel.
Voicing IV: Modern high-gain. Low amount of negative feedback (and added low-frequency resonance).
Note: That might not be 100% accurate but that's how I understand it.