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When is a sharp a flat?


baldbloke

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Those notes are called enharmonic, and the name depends on the scale/key.

 

http://en.wikipedia.org/wiki/Enharmonic

 

In the key of F for example, the major scale is: 'F, G, A, B?, C, D, E, (F)'. Thus, the 'B' is called 'B?' rather than 'A?' as we already have a note named 'A' in the scale.

 

(BTW, I didn't know this until I took my recent piano lessons. :))

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Thanks, Gitnoob. I read the link. I also hadn't realised it's not the done thing to have two similarly named notes. (Although, I think I can see why).

 

So that wasn't too difficult for me. Here's another one of those things I was too embarrassed to ask.

 

What is a "Key". Well, I had a Google and found the answer. http://ask.metafilter.com/6444/Music-Just-what-exactly-is-key Halfway down that page, there is an excellent attempt at explaining "key" with brief examples. Turns out, I knew it intuitively (Like probably lots of folk) but was never sure.

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Since you're talking about a Bb major chord, it'll be Bb when in the key of Bb, Eb, and F (those are the most likely keys, but not the only ones).

 

You probably won't see it as an A#maj unless you get into certain situations. For example, there is no such thing as the key of A# (but there is the key of Bb).

 

You'd have more of chance seeing A#m, for example, than A#maj.

 

This is first-year theory stuff, which means that it isn't rocket science. Get a teacher and learn it. Pretty cool stuff imo. :)

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Good old Wiki has a nice piece on "Musical Key" that explains the concept well and explores its relationship to other musical terms (scales, modes, chords, tonic, etc etc). There is also some info on historic development and relationship of key to different musical instruments. Lots of links to other terms too so you could spend a lot of time there:

 

http://en.wikipedia.org/wiki/Musical_key

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AH HA HA HA HA HA =D

 

I didn't get jamesp's joke until I read Mike_E_McGee's reply/quote. Time to get another cup 'o coffee. And to jamesp: Well played, sir, well played! :thu:

 

Stackabones made a good observation when he said, "There's no key of A#." This you can derive if you study the circle of fifths. Also, it helps to know that in a scale every letter note must be represented, but only once. So to take the example of the F major scale:

 

F, G, A, B?, C, D, E, (F)

 

You couldn't call the B? an A# because then you'd have F, G, A, A#, C ...

 

Only one "A" can be in a scale.

 

This really helps when you get to keys like E major (four sharps). I've played with people who will say, "Okay, this is the song 'The Weight,'* by The Band. We do it in E, so the chords go E, Ab minor, A major ..."

 

But he's calling it wrong. It's not an "Ab minor," it's G# minor, because G# exists in the E scale diatonically (E F# G# A B C# D# ), and what's more the chord in question is minor, so it's a completely diatonic progression: I - iii - IV - I.

 

It's a mistake you wouldn't make in the key of C (C goes to Em), but it gets tricky when sharps and flats are built into the key signature. Technically, in the key of E an Ab is a flatted 4th, not a third (which would be "some kind of" G).

 

 

*Regarding songs that go I-iii-IV-etc: Besides "The Weight" ("I pulled into Nazareth, I was feeling half-past dead..."), there's the Beatles' "I Feel Fine" (chorus), the Beach Boys' "Fun, Fun, Fun" (chorus), Elton John's "Crocodile Rock," and the Lovin' Spooful's "You Didn't Have to Be So Nice." For more songs that use the I-iii-IV-* progression, go here.

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in a scale every letter note must be represented, but only once

 

In a diatonic scale every note must be...

 

(I wish I'd finished that theory degree I started so so long ago...:facepalm:)

 

You can write something in the Key of A#, but you'd be a fool to. The A# major scale would look like this: A# B# C## D# E# F## G## A# Compare that with the enharmonic equivalent of Bb: Bb C D Eb F G A Bb, and you can see why any player would murder you for writing in A# major.

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In a
diatonic
scale every note must be...


(I wish I'd finished that theory degree I started so so long ago...
:facepalm:
)


You can write something in the Key of A#, but you'd be a fool to. The A# major scale would look like this: A# B# C## D# E# F## G## A# Compare that with the enharmonic equivalent of Bb: Bb C D Eb F G A Bb, and you can see why any player would murder you for writing in A# major.

 

If someone called the key of A#, you'd know that you were dealing with a fool or just someone who didn't know any better. In either case, charity is the response. ;)

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The A# major scale would look like this: A# B# C## D# E# F## G## A# Compare that with the enharmonic equivalent of Bb: Bb C D Eb F G A Bb . . .

 

 

The key of A# would actually be: A# C D D# F G A which makes it comparable with Bb in terms of complexity.

 

The system we use is just a convention that has evolved over the years. If they had picked a different system back then that is the one we would be used to and we would consider the accepted system to be odd.

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The key of A# would actually be: A# C
D D#
F G A which makes it comparable with Bb in terms of complexity.


It's just a convention.

 

You usually don't double up notes in a major scale. With the doubled up notes, you have two fourth degrees of the major scale. Also you have to have a B (the second degree) of some sort in there.

 

(This isn't really helpful for folks who can barely discern the notion of key, btw. It is very obscure and generally unusable information.) :p

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but but, obscure and unusable information is what I'm best at.

 

I disagree (respectfully) with garthman. In a diatonic scale the convention is to have one of each letter. A "B#" is the same as a "C" enharmonically, but we need a "b lettered note" to come after the A# tonic, so B# gets it. In order to get one of each letter we have to use double sharps to write it out correctly. It looks insane and complicated which is why anyone worth their salt would call it Bb. Bb major would sound exactly the same as A# major and be a hell of a lot easier to follow. I just like to point out the little details.

 

To anyone just starting out with theory, please ignore us. As Stack mentioned, we are discussing minutea that has very little practical value.

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In a
diatonic scale the convention is to have one of each letter
. A "B#" is the same as a "C" enharmonically, but we need a "b lettered note" to come after the A# tonic, so B# gets it. In order to get one of each letter we have to use double sharps to write it out correctly.

 

 

This. ^ ^ ^ ^

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Every time I try to talk about any music theory, I always get it wrong. I did this a while back on Excel.

 

The lines in full black font are supposed to be the 12 'legit' keys.

 

The grayed out lines are the enharmonic keys that are not expressed in a diatonic scale.

 

Am I right or wrong? :idk:

 

attachment.php?attachmentid=339352&d=131

 

 

[ATTACH=CONFIG]339352[/ATTACH]

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Every time I try to talk about any music theory, I always get it wrong. I did this a while back on Excel.


The lines in full black font are supposed to be the 12 'legit' keys.


The grayed out lines are the enharmonic keys that are not expressed in a diatonic scale.


Am I right or wrong?
:idk:

 

It's not terribly off, it just has some misspellings. There are 15 legit key signatures, so technically there are 15 legit keys - some are just enharmonically equivalent. Here are the 15:

 

C# major / A# minor: 7 sharps

F# major / D# minor: 6 sharps

B major / G# minor: 5 sharps

E major / C# minor: 4 sharps

A major / F# minor: 3 sharps

D major / B minor: 2 sharps

G major / E minor: 1 sharp

C major / A minor: 0 sharps or flats

F major / D minor: 1 flat

Bb major / G minor: 2 flats

Eb major / C minor: 3 flats

Ab major / F minor: 4 flats

Db major / Bb minor: 5 flats

Gb major / Eb minor: 6 flats

Cb major / Ab minor: 7 flats

 

The enharmonically equivalent pairs are Cb and B, Gb and F#, and Db and C#.

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I did this a while back on Excel. The lines in full black font are supposed to be the 12 'legit' keys. The grayed out lines are the enharmonic keys that are not expressed in a diatonic scale. Am I right or wrong?
:idk:

 

In your scale spellings, in black, you got everything right, except for the Gb scale. The fourth degree should be Cb (not "B," as you have it). Remember the rule that you must have one and only one letter name for a scale. Otherwise you couldn't write a key signature that would call for both a Bb and a B natural. The key of Gb is six flats: Bb, Eb, Ab, Db, Gb, Cb.

 

And as brahmz118 shows, you have many more problems in your grayed out scales. For the sharp keys, you need to rename all the F's and C's as E#'s B#'s. Then you need the occasional C double-sharp and F double-sharp:

C# major: E#, B#

D# major: E#, F##, B#, C##

F# major: E#

G# major: B#, E#, F##

 

Then for the last scale, Cb, you need to make this change:

Cb major: Cb (not B), Fb

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