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Cab and Amp parameters


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Newbie questions:


Can anybody give me a simple explanation of Sag, Hum, Bias, and Bias X affect my tone? I would also appreciate a few words on the cab parameters low cut, res level, thump and decay?


While I've been playing for a while and am normally every comfortable with tech, I don't have a grasp of some basic concepts in amp design and function.

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Here's the best info on the amp DEP params: http://blog.line6.com/2013/pod-hd-amplifier-extras%E2%80%94using-the-sag-bias-and-bias-excursion-settings/


The HUM control adds a hum component. It makes the amp hum/buzz. Some amps have this, and some don't. Beyond this simplicity, I don't know much about it. Something about how the 50/60Hz from the electricity powering an amp interacts with certain components of an amp.


The cab low cut is just what it says it is: it cuts low frequencies below what it's set at. Note that it's not a sudden drop-off at the set frequency, but a slope of some sort. When I make presets, I almost always set this at a minimum of 100Hz. It can help get rid of a lot of the flabby/flubbery/muddy low end.

The rest of the cab params (resonance, thump, decay) - The Resonator® - work together. (It's not actually a trademark, forum member hurghanico made that up.)

Resonance acts as a sort of mix control for thump and decay. Increasing this also increases volume, so you'd have to make the appropriate channel volume decrease. Many people prefer to set this control at zero to get a more pure impulse response (IR). Some prefer to increase it, even above the default of 50. I find increasing this gives the overall tone a more aggressive texture. Decreasing provides for a more smooth, crisp, and clearer texture. But not all situations are the same, so you have to experiment with it.

Thump kind of does what the name implies. It adds a low frequency component that's more focused than turning the amp's bass control up. So while adding bass from the amp may start to introduce some unwanted muddiness, increasing thump can help give a tone more balls without the muddiness.

Decay is time-based. I'm not sure if I understand exactly what this does. Something along the lines of controlling how long it takes the frequencies bouncing around inside the cabinet to disperse. I could be completely wrong about this one. If someone knows better, please correct.

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Perhaps misconception was a poor choice of words. When we read those old threads there is a lot of guessing, second guessing, assumptions being made, etc. No one seemed to know what any of those controls really did. That's what caused me to go off and take measurements - to see exactly what was going on and the interactions between the controls.

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