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Comment by neonscribe | Hacker News Reader

It's a shame to describe the tritone sub for G7 as C# F G# B, when the proper way to spell it is either Db F Ab Cb or C# E# G# B. Of course, then you'd have to explain about enharmonic equivalence and how chords are usually spelled with every other note.

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The C# grates on my eyes, since the V7 tritone substitute is IIb7. However, preserving the F and the B notation emphasizes the tritone interval that is inverted and shared with the substitute.

The explanation is that a seventh chord is defined as a set of third intervals. So it cannot jump from C# to F, it needs to go from C# to E#. Even though these tones are the same, the C# to F doesn't make sense. The same can be said about F G#, it doesn't make sense because it is not a third.

I transcribed the music on the ghost ship in Monkey Island 1, which features a lot of chords in the background involving fourths, fifths, and whatever we want to call the half-step in between fa and so.

Working with a MIDI file and without much grounding in music theory, I had and have no real way of determining whether to represent notes flat or sharp. I consulted several people and generally got a response of "Oh, interesting stuff! It's not clear how you should transcribe that."

I'm still interested in opinions! If you want to check it out, the score is here: https://musescore.com/user/36584999/scores/7810499

My understanding is flat vs sharp is largely about intended use. Something about some instruments makes one way or the other better for playing.

I've seen a few theories in various places:

- Match the type of accidentals used by the key signature.

- Use sharps when the melody is moving up, and flats when it's moving down.

- Use whatever accidentals give you a visually pleasing spacing of notes in "thirds" as represented on the staff. (As advocated here.)

- Use the accidentals that are physically compatible with other notes in the chord. (Only a concern for certain instruments, but e.g. I understand that the pedals on a harp affect many strings at once, so playing a particular combination of notes may require a clever approach to the pedals, indicated by what might otherwise look like an unnatural set of accidentals. This wouldn't apply to a piano, where G# is just a separate key from G, not a modification of the G key.) I think this is what you're going for?

Another example would be the bass side of an accordion where Db and C# imply different buttons (though not different sounds - there are duplicates) and they’re quite far away from each other.

The accident you use really depends on the context. If you're talking about chords, then you should follow the "stack of thirds" explanation that I gave above, it is how chord theory works. However, the other rules you mention also can be used depending on your situation. In a melody, you normally want to add accidents only when needed.

The note between fa and sol is fi or se, depending on if it's the sharp 4 or flat 5 functionally. Sharp 4 would be most common, since it comes up as the leading tone of the dominant's key, e.g. in an secondary dominant, like V7/V.

But I guess you could get the flat 5 if you did the tritone substitution of the secondary dominant of the IV, which would be bV7.

I know that fa sharp is fi and so flat is se. The point of my comment was (1) that I was having difficulty labeling the note in question, meaning I couldn't use either name; and (2) that the heuristic "use the enharmonic that doesn't interfere with other nearby notes" doesn't work, because the notes a half-step away in either direction are both in use.

Oh sorry, I misread your comment and that you were referring to a specific piece. Are you talking about the vibraphone part in the beginning? If so, I think you did it right. I wouldn't consider those little dips of the top note to be a chord change, but just a neighbor tone (https://en.wikipedia.org/wiki/Nonchord_tone#Neighbor_tone). So I'd treat it melodically and just put it on the adjacent line, with whatever accidental works. Like you did!

And then I think you may be talking specifically about measure 11. I'm pretty rusty on my analysis, but it seems like it's the iv7 chord, but starting and ending with a chromatically raised root, which is slick because it acts as a passing tone from the i chord in measure 10 and the V in measure 13. I would probably do Gb -> F -> Gb, because the F is the chord tone, and the Gb is the nonchord ornament. But yeah, probably doesn't really matter!

Yeah, I've seen things spelled this way before in barbershop arrangements. Usually because it's less accidentals. I think it makes sense from a "what notes should I play" perspective, but seeing these chords spelled in a weird way gives you insight into how some composers actually think, and all that REALLY matters is what the music sounds like.

I came here to pick this nit but you beat me to it. I think calling it Db7 is the best way to think of it, especially since in jazz it's often part of a descending sequence of II-V-I, where the tritone substitution turns it into II-bII-I. So in C major (where G is the dominant), it has to be Db.

Why do you say a tritone substitution turns it in a II-bII-I? Can it be as easily said to be II-#I-I? In that case it would be C#.

Enharmonic equivalents are usually chosen to match the direction of movement. So a descending passage will prefer to use flats.

The root is the root.

There can be only I.

I don't think this is correct. I think colanderman's answer is the right one, which is that when we're descending, we generally spell out the pitches with flats. If this were ascending, then we could have I-#I-II. But as I noted, in jazz this particular descending pattern is fairly common.

spell out the pitches

I, bII, etc. are chords not pitches. II-bII-I is a chord change. Pitches may go up or down and voices may go away or arrive. They may be part of those chords or not. And there may not even be a root pitch.

Or if you want formal theory, chords are scales [1] and there ain't no such thing as a scale with a sharp I. If you sharp the one it’s a different scale starting in a different place.

The b in bII is not an accidental and bII is how to communicate the chord in passing. I/bII is also possible to communicate a modulation (as would be vii/II, etc. if the modulation is elsewhere).

There are “enharmonics” for chords that aren”t the root of course, e.g. #IV and bV depending on intent, convention, or playability. But #I will be marked wrong on the entrance exam and only raise you standing among an avant guard that isnt accepting new members.

[1] see Russell’s Lydian Chromatic Concept.

> If you sharp the one it’s a different scale starting in a different place.

It depends on what's the function. If you want to use the tritone-substituted G7 to modulate to the sharp fourth, you'd write it C#7 and resolve it to F# (or F#-).

C#7 is the name of a chord not a pitch and not Roman Numeral Analysis. [0]

The Roman Numeral analysis would be V7/#IV if you are modulating in C. And something else if you aren't in C. Roman Numeral Analysis is independent of key or tonal center. The Roman Numeral Analysis would be bII if you are not modulating because that's how Roman Numeral Analysis communicates.

Thinking about Phrygian mode. The two is always a bII.

{0} As an aside, in The Common Practice the bII is often notated N6 (for Neapolitan 6th) to set up a perfect cadence, i.e. I-N6-V-I.

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