Common Amp Settings

Parameters

This is a list of the most commonly used settings found across various amps in the Line 6 Helix, Helix Rack, Helix LT, and HX Stomp.

Master

Adjusts the amount of power amp distortion. This parameter is highly interactive with all other power amp parameters—the lower the Master is set, the less effect the other controls will have.

Sag

Lower Sag values offer a "tighter" responsiveness for metal and djent playing; higher values provide more touch dynamics & sustain for blues and classic rock riffs.

Hum, Ripple

Controls how much heater hum and AC ripple interacts with your tone. At higher settings, things get freaky.

Bias

Changes the Bias of the power tubes. Lower values achieve a "colder" Class AB biasing. At maximum, the amp is operating in Class A.

Determines how the power amp tubes' voicing reacts when pushed hard. Set low for a tighter feel. Set high for more tube compression. This parameter is highly reactive with the Drive and Master settings.

Quick Notes

Invented control starting point for neutral settings (setting to simulate the real stuff, without those invented parameters. But you can play with this values, it's up to you (no limits):
Presence for No Presence amps should be zero (all the way counterclockwise). Exception Jazz Rivet (P: 50%).
Eq bonus controls to noon (50%) for No Mid, No Bass, No Treble amps.
Master parameter for no master amps to 100%.
Real amps with Volume means Gain in Helix. Volume in Helix is like a mixer to compensate final modeled output level (obviusly it doesn't exist in any of the real amps).
To attenuate "Crossover Distortion", the best parameter in Helix is "Bias", increase it from 6 to 8 as general rule just in case you need to mitigate it.
The default Line 6 amp settings parameters for Helix, when you open a modeled amp, are also a good starting point, normally they are close or exactly in concordance with this. Tip : double click in the parameter to come back to the default one.
For Pre Amps models in Helix, some power amp related parameters (i.e presence in general ; or cut tone with Vox amp )are not present, but they modeled also Master and Sag with PreAmps.
All amps are modeled on the Input 1 (High). If you want simulate Input 2 (low), then use a gain block to take 6dB off the signal, and change the input impedance to something lower; somewhere between 68k and 150k.

Further Tone Control

Originally posted by Ben Adrian here.

I'll do my best to answer this while also playing it safe and not giving away anything that might get me a stern talking-to.

Bias on cathode biased amps

Many people have an association that cathode biased = class A. This is usually not true. However, most cathode biased amps are running the tubes hotter than most fixed bias amps. The Bias control affects the balance of distortion between saturation and cutoff in the power tubes. Proportion changes depending on the idling state of a power tube; if it's idling hot, then there will be more saturation and less cutoff, and if it's cold there will be more cutoff and less saturation. The bias control affects where the idling state of the tube is "located"; if it's hot or cold. Another way of putting it might be that we can virtually change the value of the cathode bias resistor in a cathode bias amp.

All these extra knobs

If an amp has a small number of knobs, then we will invent the knobs in a way that makes the most sense to us. First, let me say that the Channel Volume (ChVol) knob is ALWAYS a flat response, post amp model level control. This is like a fader on a console. It's in the amp model, but it's not tied to the tonality of the amp model. It's how I level different presets so that they play well together.

The Drive knob corresponds with the Drive or Gain knob on master volume amps. With amps that don't have a master volume, it corresponds with the Volume knob. So, on the Deluxe model that you reference, the Drive knob is the Volume control on the front panel.

The Master Volume knobs in Helix map to the Master volume knobs on amps with Master Volume controls. If the amp does not have a master volume control, then we add one similar to where an amp tech might add one to an amp if the amp was having one installed. In the case of the Deluxe, this is between the preamp and the power amp. This can be thought of as a passive volume reduction. Master @ 10 is like it's not in the circuit. As it is turned down, the level from the preamp into the power amp is reduced.

Tone controls. We try to make them fit the character of the amp. In the Deluxe Reverb, the tone controls are exactly like that or a twin reverb except the 10k linear midrange knob is replaced with a fixed 6.8k resistor. If you want to match the model to the actual amp, set the model between 6.1 and 6.8 (values drift in the real amps. My idea, though, was to make the midrange knob on the deluxe behave like the midrange knob on other black-face fender circuits that have a midrange control.

In other amps, tone controls gets invented on a per-amp basis. In the tweed champ, the bass and treble are after the amp modeling, but the midrange control is between the two preamp gain stages. The midrange knob can become a cool drive feature. In some amps, the invented controls come between the preamp and the power amp. In short, we tried to make it sound good, and we tried to respect what is happening in similar classic amp circuits.

Cheers!

Thank you amsdenj of the Helix community for providing further information about the Common Amp Settings and duncann for providing the link to Ben Adrian's information regarding tone controls.