What exactly does Definition (really) do?

Difference between harmonics and overtones aside (which I think are one and the same), I've always understood it like this:

Higher definition - more lower frequencies are rolled off before signal is being fed into the overdrive/distorting part of the signal processing;

Lower definition - less roll-off of lower frequencies, meaning the overdrive or distortion will be driven (ha ha) mostly by the lower frequencies, as these lower frequencies have more energy per "frequency band". Which can lead to muddiness if overdone.

I think of it as a tilt EQ applied to the distortion generator (for lack of better terminology).

All of the above is speculation on my part.

that is why you try it and know what it does in the profiles

So, harmonic and overtone indicate related, but different things.

A harmonic is, by definition (no pun) a clean multiple of the fundamental (2, 3, 4, 5.....etc). Overtones can be any frequency, so long as its above the fundamental. So, a harmonic is an overtone, but an overtone doesn't have to be a harmonic.

What I read the manual as saying is modern amps affect both harmonics and other overtones, where vintage amps distort lower-order harmonics and not necessarily overtones.

Quote from Ruefus

A harmonic is, by definition (no pun) a clean multiple of the fundamental (2, 3, 4, 5.....etc). Overtones can be any frequency, so long as its above the fundamental. So, a harmonic is an overtone, but an overtone doesn't have to be a harmonic.

Good point.

Though in the description above I'd guess that both words should be "overtone", since I'd assume that an amp - vintage or modern - has no way of discerning whether something is an overtone or a harmonic.

¯\_(ツ)_/¯

The only people that could answer that for certain work for Kemper. As you’re aware they don’t normally answer on here.

I agree with everything said so far. Def seems to be an EQ adjustment at the input. My guess is it rolls off the lows. And agree it could be almost a tilt eq.

Assuming it does not do a great deal more than input EQ, you could attach the Kemper to a sound card and run Room EQ Wizard on it to see the actual EQ changes.

Quote from Dynochrome

I'm going with the belief that definition is adjusting if high or low harmonics (overtones?) are being selectively distorted and how much.

That's in essence the effect of what I describe. It's what you're saying here already, just want to be clear

If it were ‘just’ an EQ, then people would’ve been using EQs to do the same thing for ages.

At least to my ear…..that’s not what’s going on.

Quote from Ruefus

If it were ‘just’ an EQ, then people would’ve been using EQs to do the same thing for ages.

At least to my ear…..that’s not what’s going on.

On second thought I suspect that you're right.

For reference, here's what the manual states in full:

Quote

The “Definition” parameter controls the characteristic fingerprint of the preamp. The PROFILING process

automatically sets “Definition” to a value that represents the reference amp. You could, for example, use it to

modernize the PROFILE of a vintage amp without having to use additional effects. Alternatively, start with a

PROFILE of a modern tube amp, and use “Definition” to give it a more vintage sound when driven into distortion.

You can also use “Definition” to align the sound of your guitar to the sound of your amp, if required. Don’t be afraid to

keep experimenting until you get the balance that sounds best to you.

Vintage amps distort the lower harmonics in the guitar signal which gives them their bluesy sound. These amps were

originally designed to deliver a clean sound, so if you want a creamy distortion, these amps need to be driven by a

typical transistor-based device like a treble booster. Modern tube amps use a different approach, in which the higher

overtones of the guitar strings are the driving force for the distorted sound. The expensive boutique amps take this

concept one step further, by providing an extreme level of top-end frequencies and a large dynamic range. The

distortion has a sparkling quality to it and preserves every nuance of the strings and pickups. Together with the

characteristics of the actual speaker, the individual distortion behavior creates the fingerprint that identifies the

amplifier.

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...which doesn't explain much in the way of how the specific definition control relates to the sound or how it works - it first talks about the control in very vague terms, than goes on to describe the sounds of actual amps - without really linking the two (or even explaining how a profile reacts to changes to the control, higher or lower).

Quote from Michael_dk

...which doesn't explain much in the way of how the specific definition control relates to the sound or how it works....

Which I suspect may be considered proprietary information.

Other than a Quad Cortex, I'm not overly familiar with the controls on a Helix of AxeFX (nor most any other digital solution).....but I've never heard anyone refer to the Definition control as "Similar to X on Y unit."

In comparison to a Profiler, the amp controls available on the Quad Cortex are rudimentary at best. I found that terribly annoying.

Quote from Dynochrome

I kinda recall either on here or an interview with someone from Kemper that explained it as the distortion/ harmonic thing but I haven't searched for it I was being lazy and figured some others would know.

NOW you tell us!

I've always considered the Definition as just a light-dark knob kind of like a light fixture dimmer control. Makes it easy for me to understand and apply.