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I'm studying in an online game music course, and I'm experimenting Modes to add unusual sound to the music. I'm a complete newbie in music. So let's have the Locrian mode, the root chord is a dimished one, so the V is dimished. As far as I read, power chord are created with a V, so, if I want to play a power chord on the root in locrian mode, do I have to use the dimished fifth, or have I to use the fifth, playing a note that does not belong to the key? I tried the two: strangely the one with the fifth, playing the note out of key sounds better ( ie, it produce a dark feeling ) but is it correct to play?

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    Sounds like you are doing very well for a complete newbie - keep it up! – Stinkfoot Sep 2 '17 at 19:21
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If you want to be 'faithful' to the mode/scale you are in (in your case the Locrian Mode), you have to use the diminished fifths. For instance, the Power chords would be B-F (diminished fifth), C-G (natural fifth), D-A (natural fifth) etc..

It's not uncommon though to use notes outside the mode. You can use the Power Chord B-F# which is a natural fifth. Musicians do this all the time.

Really depends on what you want to create. My suggestion would be to try both out and see what you like best. In some cases you might like the diminished sound and in some other cases, you might want the neutral sounding natural fifth.

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The term 'Power chord' normally means a perfect 5th. It can sound like a reinforced single note, because of the way harmonics work. But then it's often played on guitar with a distorted sound, so the harmonics are all mussed up anyway! Whatever. We know what a 'Power chord' sounds like.

You are perfectly at liberty to play a diminished 5th in a 'power chord' sort of way. It won't have the same effect of reinforcing the harmonics of the bottom note. It would probably be inaccurate to call it a 'Power chord'. But that doesn't matter. If you like the sound, use it.

Don't worry about theory 'allowing' you to do things. Theory describes, it does not command. (I say this a lot, and will continue saying it until it sinks in :-) If you're thinking harmonically, and are going for a Locrian feel, it may be better to keep all notes within the mode. Or you can belt out a Locrian scale, each note played as a 'Power chord' with the (perfect) 5th above added. Theory will help you describe what you're doing. It won't tell you WHAT to do.

  • thanks for the reply: actually the one that fit better is the "standard" power chord, the one that respect the model, sounds weak, maybe the extra note give some extra "distorsion" that increase the tension... – Felice Pollano Sep 1 '17 at 11:30
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Here's the script I used to generate the below plots

As Laurence Payne said, it's only a power chord if you use a pure fifth. Any chord you put through distortion will give you not only the frequencies actually played, but also new components that weren't originally there at all, via intermodulation.

plotWindow . distortionCompare $ sineSig 163 ^+^ sineSig 308

Intermodulation-frequencies creating by distorting a mixture of two sinusoidals

Recall that even a single note on an instrument like guitar corresponds to a whole bunch of sinusoidial frequencies, however because these are in neat integer ratios those actually line up perfectly with the new distortion-frequencies, that's why distortion works fine on single guitar notes – it simply gives a more agressive, overtone-rich spectrum but doesn't change the harmonic content itself:

plotWindow . distortionCompare $ stringSig 100

How the spectrum of a single guitar-like tone is extended through distortion

Similarly, if you distort a powerchord (in which the fundamental frequencies are in a neat 3:2 ratio) the result has merely a “filled up” spectrum, but the new frequencies align perfectly with the already-there harmonic content, thus you get a very fat and agressive, but still clear sound:

plotWindow . distortionCompare $ stringSig (note "A2") ^+^ stringSig (note "E3")

How the spectrum of a powerchord is extended through distortion

In fact, all the frequencies you see here are integer multiples of 55 Hz, i.e. of A1. Therefore, this sound actually makes sense even in A-Locrian, despite the E that isn't supposed to fit in that scale.

Incidentally, the harmonic-alignment effect still kind-of works with a major third:

plotWindow . distortionCompare $ stringSig (note "C3") ^+^ stringSig (note "E3")

How the spectrum of a major third (in 12-edo tuning) is extended through distortion

Here, the new frequencies fit pretty well in the spectrum, but are significantly “smeared out”, which makes the signal dirty in a way that starts to resemble white noise. That's actually an artifact of the tuning system: I've used the common 12-edo tuning above, which handles thirds pretty badly. In the correct just intonation, major thirds distort in fact very nicely:

plotWindow . distortionCompare $ stringSig (note "C3") ^+^ stringSig (5/4*note "C3")

How the spectrum of a major third (in just intonation) is extended through distortion

Anyway, for something as dissonant as a tritone, all bets are off:

plotWindow . distortionCompare $ stringSig (note "B2") ^+^ stringSig (note "F3")

How the spectrum of a tritone is extended through distortion

Here, the intermodulation frequencies are all over the place. There's nothing the ear can really cling to anymore, so it won't sound powerful anymore but just annoying.

So no, it doesn't make a lot of sense to play diminished fifths when accompaning Locrian mode on electric guitar. Better just play powerful deep single notes if you want a dark sound, or indeed standard powerchords, as already suggested.

Alternatively: it is actually possible to re-tune a tritone-near interval to something that can be resolved in just intonation, namely the 7:5 ratio that also occurs in the harmonic seventh chord (aka Barbershop seventh):

plotWindow . distortionCompare $ stringSig (note "B2") ^+^ stringSig (7/5*note "B2")

How the spectrum of a 7:5 “tritone” is extended through distortion

You can achieve that by tuning the F note of the B-Locrian scale down by 17 cents from its 12-edo frequency. That's not really feasible on a 12-edo guitar, but it can be done on a many-fretted microtonal instrument. 31-edo is definitely capable of this. 22-edo might also work.

Ron Sword makes such guitars.

  • Good graphs. Such representations put the lie to the claim that how we hear music is "entirely subjective" and "one man's dissonance is another man's consonance". – Stinkfoot Sep 2 '17 at 19:25
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    @Stinkfoot well, yeah... although obviously it doesn't say anything about what amount of dissonance is good/bad. Furthermore it's all only so clear when you actually toss in a significant amount of distortion, concretely 1D time-domain nonlinear distortion. Which is mostly characteristic for analogue electronic processing, and thus to ≈1920-1990 Western music. In most other cultures, the interaction between voices is largely linear. And all the discussion only applies when you start out with tones consisting of integer-multiple harmonics, e.g. for Gamelan it doesn't make sense at all. – leftaroundabout Sep 2 '17 at 19:36
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    what amount of dissonance is good/bad Regardless - there is a math and physics that determine the degree of dissonance the ear perceives. The point is that physics is fundamental to how we hear music, in the same way as how we see colors. We can no more hear a perfect 5th like we hear a tritone, than we can see green when the color is purple. I'm making this point because there are those who believe that Functional Harmony is just some sort of meaningless "European" convention. It's not, no more than the overtone series is. – Stinkfoot Sep 2 '17 at 20:02
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The only difference between the Phrygian and Locrian modes is that the fifth scale degree of the Locrian mode is 1 semitone flat from the Phrygian one. At this point, unless you want your Locrian music to sound like it's in the Phrygian mode instead, I'm afraid you're stuck with diminished fifths for playing "power chords" on the root.

  • This is also true, I noticed that probably the correct mode to play, is Phrygian! – Felice Pollano Sep 2 '17 at 14:51
  • @FelicePollano but then the question is all wrong! Phrygian mode is of course fine to use (done all the time in metal), but it's something entirely different from Locrian. – leftaroundabout Sep 2 '17 at 18:26
  • @leftaroundabout possibly it is: I'm a newbie :) Actully is true anyway that B phrygian and B locrian differ just for the F#, so they are not so far, anyway, are they? – Felice Pollano Sep 2 '17 at 18:29
  • Sure, they are closely related, but that diminished fifth is the crucial distinguishing part of the Locrian mode. Changing it to Phrygian is about as character-changing as switching from melodic minor to an ordinary (Ionian) major scale. – leftaroundabout Sep 2 '17 at 18:42

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