#1
Not sure if this belongs in MT or GG&A. It seems to best fit here. We'll be talking about distortion to a sound signal from clipping only.

So we all know what distortion is. Or at least I'll presume so. If not, research it. And we all know what distortion does under superficial analysis: It makes your guitar more aggressive, sustains, and of course adds this magical "gnarl".

But at a deeper, sonic and systematic analysis, what's going on here? Particularly, I've noticed that even a heavily clipped monophonic signal sounds "normal" aside from long sustain and relative fullness. But that "gnarl" that we all know and love isn't really there.

However, as soon as you play two notes together, either in a chord or legato movement, that gnarl is very prevalent. Especially in thirds, the clipping is noticeable. It sounds... bad. In fact, I avoid playing heavily clipped thirds in general. In full chords, the gnarl seems to fade into the chord structure, which I've been led to believe that this noticeable gnarl, prevalent in chords, refers to the "harmonic content" of a distorted signal.

Why does that happen? Why do single notes clipping track without that same noticeable gnarl as chords clipping do? Even further, presumably along the same lines, why do certain intervals (1st and 7th in major, 7th (octave below) and 4th in major) seem to add similar clipping, even at clean tones?

In my mind, it is somewhat in a similar fashion to how speakers break up. After all, distortion boxes were inspired by overdriven amps. I guess that single notes do not send but so much "power" and frequency information in the signal, allowing the speaker/distortion box to produce the frequency, and also to distort the signal without gnarl using a distortion box. When two (or more) notes are played, the signal is stronger and, for a speaker, the cone is trying to vibrate at all the frequencies being played. So, it starts to "clip" or really it starts to blend the frequencies together, resulting in harmonic content and distortion. Distortion boxes just emulate that. And somehow, speakers are able to produce loads of nuances and frequencies without distortion.

So, clipping diodes would act much in the same way that a speaker would blend the notes together when under overdrive. The diode is trying to clip more than one frequency, and it has to blend the two in a disgusting but beautiful bleh.

Of course, I'd like to know what is actually going on.
Last edited by Will Lane at Feb 10, 2015,
#2
Quote by Will Lane
However, as soon as you play two notes together, either in a chord or legato movement, that gnarl is very prevalent. Especially in thirds, the clipping is noticeable. It sounds... bad. In fact, I avoid playing heavily clipped thirds in general. In full chords, the gnarl seems to fade into the chord structure, which I've been led to believe that this noticeable gnarl, prevalent in chords, refers to the "harmonic content" of a distorted signal.

Why does that happen?
Beats sound particularly funny when distorted, and are not particularly noticed as beats 'cause clipping distortion creates a lot of compression.

For further reading - http://en.wikipedia.org/wiki/Beat_(acoustics)
Quote by Will Lane
In my mind, it is somewhat in a similar fashion to how speakers break up.
That though has nothing to do with it.

Speakers don't clip signals, speaker create distortion 'cause they're heavy and it's difficult to control their movement accurately.
Quote by Will Lane
After all, distortion boxes were inspired by overdriven amps.
Yup, but that distortion comes from the amp, not the speaker.
Quote by Will Lane
So, it starts to "clip" or really it starts to blend the frequencies together, resulting in harmonic content and distortion.
Say you play a note, which has a fundamental frequency of x and has a certain number of harmonic overtones, and then you play another note with a fundamental frequency of y and the same number of harmonics as the note of which fundamental is x.

If you play the notes of which fundamentals are x and y together, the number of resulting harmonics will be the number of x harmonics (fundamental and overtones) and y harmonics (fundamental and overtones), nothing more than that.

Playing a chord doesn't create harmonics, it just sums the harmonics of two signals.

Of course, a perfect 5th will have less harmonics than a major 7th (more harmonics in common, so less different harmonics), hence the result will be more smooth sounding if you're talking audio and more tense if you're talking music.
Quote by Will Lane
Distortion boxes just emulate that.
A simple distortion box clips your signal by raising its gain too much, end of the story.

No trickery nor magic around it.
All of the phenomenons you're thinking about are related to simple waves physics, not electronic mumbo jumbo created to replicate "vintage stuff" that wasn't in any way related to (now) relatively old equipment.
Quote by Will Lane
And somehow, speakers are able to produce loads of nuances and frequencies without distortion.
When you play two sine waves, say f(x) and f(y) with f being a sine function and x and y being two different frequencies, the result is simply f(x) + f(y) - the simple algebric sum of the two functions, not some pair of split signals that blend magically in the speaker.

Refer to high school maths and physics for further reading.
Quote by Will Lane
So, clipping diodes would act much in the same way that a speaker would blend the notes together when under overdrive.
Clipping diodes simply clip signals, while speakers don't.

Also speakers aren't "under overdrive", speaker can either reproduce (cleanly or not) an overdriven signal, or they can be overdriven, resulting in distortion of a signal right before frying.
Quote by Will Lane
Of course, I'd like to know what is actually going on.
I have the distinct feeling that you didn't read as much about distortion as you wanted us to believe by writing them first few lines.

Read about acoustics.
It's as simple as that.
Though high school maths will help you understanding how signals can be represented.
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#3
Just a disclaimer that this is based on A-level physics and casual research, I promise nothing in terms of accuracy.

Quote by Spambot_2
If you play the notes of which fundamentals are x and y together, the number of resulting harmonics will be the number of x harmonics (fundamental and overtones) and y harmonics (fundamental and overtones), nothing more than that.

Playing a chord doesn't create harmonics, it just sums the harmonics of two signals.

Of course, a perfect 5th will have less harmonics than a major 7th (more harmonics in common, so less different harmonics), hence the result will be more smooth sounding if you're talking audio and more tense if you're talking music.

I feel like this is basically the important stuff. A note produced by a string will have harmonics, notes at frequencies that are precise multiples of the fundamental's. As noted by the more detailed and better-informed above reply, these are all sine waves, and they all combine simply by addition into a more complex waveform.

Harmony is essentially as many of these harmonics as possible syncing up as regularly as possible. Consonance, in the general usage of the term ("nice" intervals), is where they sync a lot, while dissonant intervals and chords sync less frequently. Intervals that sync really irregularly are basically a lack of harmony, also known as being out of tune and not of much use in traditional music. Where the various waves sync so little, the gradual shift of the waves in and out of phase with each other creates a pulsing "beat" as referred to by spambot. Distortion emphasises this effect a great deal. This is pretty easy to demonstrate: put on a lot of distortion and do a slow unison bend. Especially with a lot of bass, neck pickup and tone low etc., the pulsation is very pronounced. As the notes shift closer in frequency the beat becomes less rapid (I need to check if I got that the right way round...) until you hit the sweet spot where they synch and have a more-or-less constant volume. Which is why you sound crap if you're not in tune, but worse if you're not in tune when using distortion.

Spambot's answer was more complete, but I just felt like clarifying it a bit. Essentially that's some basics of harmony and "being in tune" as I understand it. Distortion cuts off a lot of the clarity which leaves you with many of "discrepancies" between notes being more pronounced relative to the notes themselves. In the case of a perfect fifth or fourth those discrepancies are like crushed ice in a milkshake; that is to say, beautiful texture. In the case of, say, a minor second or semitone it's more like drinking sand.
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#4
So what I'm asking about really isn't about distortion, it's about "beats". Distortion just makes it much more noticeable. I have heard beats before and wondered what causes them, and they have been referenced in my "studies," but I never knew the name for them.