Setting input sensitivity

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Understanding Clean Sense & Distortion Sense

I feel like the best explanation of how these controls operate was given by Trazan:

You can think of distortion and clean as two parallel paths in the Kemper. Every profile contains a clean and distorted sound. The Gain control not only changes the amount of gain on the distorted path, but the volume of the two paths. Gain at 0 contains only clean tone. Gain at ~4 or above is only distorted tone. Anything in between is an interpolation of both.

  • Clean Sense (CS): whether CS controls loudness depends on how much distortion there is (what you hear). It affects loudness from completely clean into some distortion (Gain 0-4 on my setup, with DS at 0). How the amp is profiled doesn't matter - only the current Gain setting matters.
  • Distortion Sense (DS): A pre-gain level adjustment of the "distortion path". It results in more/less distortion and applies to all rigs. Whether CS has an impact on loudness still only depends on what you hear (how much distortion). IOW, the transition between clean/dist on the Gain control will be shifted up/down as you adjust DS.

When you push the Input button you have Gain, CS and DS right beside each other, so you can play around with them simultaneously and quickly hear the results

Trazan

Define Clean vs. Distorted

  • Clean - Gain at 0
  • Distorted - Gain at 4 or above
  • Crunch - Anything between Clean and Distorted

Again, the "Crunch" settings would be an interpolation of both Clean and Distorted - Clean Sense has more and more impact the lower Gain is set.

Why Adjust Clean Sense

Level volume of Clean and Distorted Sounds

The KPA has a unique design in that every profile has a wide range of distortion saturation, ranging from completely clean to (basically) mush. Normal amplifiers will have no output at 0% gain, making it unusable. The KPA's Gain knob is designed to affect the amount of distortion, not the volume level - 0% gain is a usable setting. This allows the Gain parameter to be assigned to a midi expression pedal for some interesting sounds.

Yet because different guitars/pickups have different output levels and distortion necessarily introduces heavy compression, there is no means to automatically guarantee a consistent volume between distorted and clean sounds. This is why the Clean Sense parameter was included.

Note: The guitar volume pot still affects the KPA like a real amp. Turning it all the way to 0% will result in no signal being sent to the KPA.

Avoid Clipping Clean Sounds

The Input LED indicates how "hot" the raw input signal is after being adjusted by Clean Sense. I'm not convinced it indicates actual clipping. With my Clean Sense turned up higher than usual, I can easily drive this LED to red; however, I only notice clipping on clean tones. Even when paying very close attention, I notice no effect on distorted sounds. Normally, you can hear input clipping on a distorted tone, particularly on single notes and leads - the pick attack is poorly defined and harsh. Even using extreme settings just to test, I notice no tone change.

Clean tones have obvious clipping when Clean Sense is turned up too high. There is mention that the KPA's input features "soft clipping", which functions more similarly to a brick-wall limiter than digital distortion. However, nasty digital distortion is clearly audible on extreme settings.

Quick Adjustment for Different Guitars

It's a good idea to lock the Input section to apply globally. Then when you change guitars, you can adjust Clean Sense to preserve the volume levels between clean and distorted tones. You can even save presets of Input settings for each guitar you use.

Why Adjust Distortion Sense

Maintaining Distortion Levels for Different Guitars

It's a good idea to lock the Input section to apply globally. Then when you change guitars, you can adjust Distortion Sense to preserve the idealized gain dialed in for each rig. You can even save presets of Input settings for each guitar you use.

This is great for the studio where you might be using 10 different rigs but want to try 3 different guitars. Instead of saving 30 rigs (10 for each guitar, compensated for that guitar), you can just save 3 Input presets.

Global Gain Adjustment

There are many reasons to desire a global gain adjustment to all your patches:

  • You raised/lowered your pickup height for tonal reasons but want the same gain levels
  • You are using different strings (ex. cobalts vs. nickel) but want the same gain levels
  • You are using a new pedal in front your KPA for tonal reasons but want the same gain levels
  • You dialed in all your rigs for a good solo guitar sound, but find a double or quad tracked recording sounds better with less gain
  • You dialed in all your rigs at bedroom level and find they are too mushy when cranked up
  • You are an indecisive individual and want to try to adjust many rigs at once
  • You want to simulate as though you changed guitars by adjusting all your rigs' gain saturation

Input LED

Mr. Kemper has said that you should use your ears rather than eyes when setting Clean Sense. Many will look at the Input LED, and if they see it flash red, they believe Clean Sense must be too high. But the Input A/D converter features soft-clipping. Small spikes hitting red likely don't result in any perceivable clipping.

And when using your ears, test on clean tones, not distorted tones. I don't believe Clean Sense has any perceivable impact on distorted tones.

Reamp Sense

Reamp Sense functions identically to Distortion Sense, but it only applies to the reamp inputs (Return Input, SPDIF).

More Info

Distortion Sense is essentially an input gain control. For lower output pickups you can raise it to get more gain or lower it for guitars with hotter pickups. This clearly follows some type of exponential curve in order to be more effective as gain is engaged.

These controls are necessary on the Profiler because we offer the volume compensation for clean sounds. That means when you turn the gain to zero, you get a fully clean sound at regular volume. You could not do this on an analog guitar amp. But if your guitar itself is loud or soft, the clean sound would become too loud or soft. This is what you level with Clean Sens. It took me a while to create this, and I understand that this might be a bit confusing, as those controls do not react as you would be used to. But just use it as described and don't think about it deeper.

Clean Sense is to balance between clean and distorted settings of the same profile, as well as between different clean and different distorted rigs.

ckemper

Clean Sense should be set so that your clean rigs have the same volume of your distorted ones and it does not influence how the guitar is driving the distorted sounds. The Distortion Sense does influence how hot the guitar is driving the distorted sounds and practically compensate for too hot (reduce it) or too soft (increase it) PUs.

Q: So why not just use the cab volume (or amp volume) to balance out the clean profiles vs. the crunch profiles? Does the clean sens actually influence the tone, or just the volume?

Clean Sense is not a simple input gain: you will notice that it will not affect the gain of a distorted sound, while it has an impact on the pure input gain. A correct Clean Sense setting is not crucial for an optimal sound. It is merely a feature to globally balance the level of clean sounds to match the level of crunch and high gain sounds. Still it should be turned down a bit for very hot guitars to prevent clipping. At the same time, if you feel that your guitar is too weak for clean rigs (compared to distorted rigs) and that bothers you, increase it. It will not color the sound or change the feel, just the volume.

Distortion Sense is also not a simple booster, as it does not affect the gain of clean sounds.

The Clean Sense will also care for the best levelling of the digital instrument input, as some of you stated. Doing this is easy: just set your guitar so that clean sounds feel as loud as distorted sounds. When done, there is no risk to clip the input with that guitar.

ckemper

The default for Distortion Sense is the middle position. If your guitar is quite hot, turn it down: it will be as you would turn down the gain on all profiles. And yes, if your guitar does not clean out well, there might be too much gain and distortion.

ckemper

The Clean Sense is just a gain control for your guitar, that has no impact on distorted sounds, but lets you adapt the volume of clean sounds. It is like levelling the clean channel of your tube amp to match the level of the distorted channel. It does not change the sound, only the volume. There are many advices around, that you have to adjust those two parameters correctly to achieve the optimum sound. Not true, just a myth. Distortion Sense is just based on this question: when you play this particular guitar (or this input setting that you are about to save) would you like all of your dirty rigs to sound more or less dirty? Beyond this, there is no reason to use it at all. It does not improve or colour the sound, it is just a neutral booster. We will make this parameter global parameter in a future update. (as of Mar 2013, NdA)

Some simple advices:

  1. Adjust Clean Sense, if you feel that clean rigs don't match the level or power of distorted rigs. Don't judge by the input light, trust your ear.
  2. Hands off Distortion Sense!
ckemper


Q: Please describe the interaction between Clean Sense and Distortion Sense. How do you set the correct level of Distortion Sense? The input light seems to be independent from its settings.

A: ...till you don't put a pedal in front of it, then it starts working. With the guitar in to the Profiler I leave Distortion Sense to 0 and use only Clean Sense.


Gain and Distortion Sense act the same. Their scaling is different though. Increasing Distortion Sense by 5.0 is equivalent to decreasing Gain by 1.5.

ckemper

Clean Sense and Distortion Sense do not color the sound. There is no coloring or additional dynamic whatsoever connected to these controls. Clean Sense only adapts the input level to the Profiler. Doing that, it takes care about the loudness of clean sounds while not altering distorted sounds. Distortion Sense does the opposite: it adapts the level vs. gain for distorted sounds, if that's required.

ckemper


Those parameters also affect how loud a patch will be when raising and lowering gain. For example, If Distortion Sense is low as you add gain from clean it won't get louder; but, as you back off gain it will get louder. Raising Distortion Sense will add volume as you add gain. Very cool feature actually.

I find the Distortion Sense knob helps a good bit with the overall lack of gain I'd been experiencing on single-note lines vs. chords. I've usually got it on 1.9 or more - I've not regretted cranking this knob on saturated sounds yet. Now if I could just get a bit more "squish" out of the response...

If you get input clipping on clean sounds, you need to reduce Clean Sense. I have a Häussel Tozz XL in the bridge position which really has some extremely high output. So when adjusting Clean Sense I select the pickup with highest output and just hit the strings as hard as I can. The input led should become orange, but not red. I need to reduce Clean Sense to about 3.1. But after that even the TOZZ XL can produce a nice clean tone.

Take care: rolling back the guitar volume pot is not the same as turning the sense parameters down: it can color the sound a bit, as the passive guitar circuit is not necessarily linear.

Distortion Sense is something that is adjusted to taste by yourself. If you feel that your Profiler rigs have overall less gain than you'd like, you raise it, if you feel the other way around, then you lower it. This simple. Volume balancing should be easily achieved by the Cab/Amp volume controls, there's no need to touch the sens values for this.

Clean Sense shall not, by its definition, change the gain of any distortion, not even a distortion in the loop.

The Distortion Sense will affect the Direct Out, too. You should set it to zero, when you run your reference amp for profiling. The Clean Sense has no impact on the Direct Out.

ckemper

Some users report that dynamics improve and notes seem to get more articulate if the Clean Sense is set so that the input LED barely lights yellow (rather than red) if not at all.

Slightly distorted sounds will still be affected in volume by Clean Sense, since there is a certain transition window, not a hard distinction. The smooth transition is needed, since there is a soft transition between clean, crunch and heavy distorted sounds as well.

ckemper

Setting Clean Sense & Distortion Sense

  • Hold the Input button. You'll see the adjustable Clean Sense and Distortion Sense parameters appear at the bottom.
  • Put your guitar on highest output configuration and strum pretty hard.
  • Set those controls accordingly: you want to be just below clipping the input LED.
  • Click Store and name your "input preset" (by guitar name for example). Click Store again.
  • You can now lock input by holding down the Lock button.

This will lock the input setting for all rigs. But remember to lock the Input section: if you don't, the input settings will be changed with every new rig that you use.

You can repeat the procedure using different guitars (settings will be different) and save multiple input configurations for them so that you don't have to spend time working it out again. Then, in the future, when switching from an LP to Strat, you can hold down Input then turn the Browse knob to select the guitar inputs you have stored. This is a global setting I feel really meant to set and forget not to constantly twiddle from profile to profile as such... Once you have settings done for a guitar...forget about it and play!