In chord a construction, in a Adim, for example, is it indifferent to have instead of A, C, D#, have, A, C and Eb?
In chord construction, in a Adim, for example, is it indifferrent to have instead of A, C, D#, have, A, C and Eb
A dim chord is made of thirds so the D# would be incorrect. A to D# is an augmented fourth.– PeterJSep 25, 2019 at 13:28
But aren't the notes the same @PeterJ?– user63382Sep 25, 2019 at 13:36
The pitch is the same, but if you use a D# the chord is no longer diminished. It is diminished because of the diminished fifth between A and Eb. Imagine a C minor chord notated with a D# instead of an Eb. It would be highly confusing and misleading.– PeterJSep 25, 2019 at 13:43
Thus A,C, Eb is correct and A,C,D# would be not the best. But if you construct dim7 chords you can build an dim7 on each tone of the tetrad A,C,Eb,Gb and transform this chord to D#,F#,A,C and all other enharmonic exchanged chords. That's why the dim7-chords are useful for modulation.– Albrecht HügliSep 25, 2019 at 13:45
@Tim: did I say something different?– Albrecht HügliSep 25, 2019 at 13:59
This is one of the most common misconceptions in aspiring musicians. Saying that because D♯ and E♭ (or any pair of "enharmonic" notes) sound the same, therefore you can choose either one is like saying that because "they're" and "there" sound the same, you can use either spelling. They have the same sound, but differing semantics.
There are probably tons of questions about that on this site already. A quick search, for example, found these:
- Why do notes have multiple names?
- Which enharmonic to use when writing down a sequence of chords
- Using the correct enharmonic equivalent
Intervals are counted diatonically, meaning that a scale will contain one note with each of the seven letters (whether that note is natural, sharp, or flat). A typical chord within that scale will be built on thirds, which means it skips every other letter. So any triad starting on A will have the notes (A, C?, E?). The C and E have question marks to indicate that whether they are natural, sharp, or flat depends on what type of chord you are building. So A minor is just (A, C, E), while A major has a raised third (A, C♯, E), and A diminished will have a lowered fifth (A, C, E♭).
Diminished chords (triads) are made up from a root note, a m3 and a diminished 5.
Therefore, using A as the root, the m3 will be C natural, and the D5 E♭. That's how it's spelled. Yes, on a lot of instruments you could play A, C D# notes, and it would sound exactly the same. But that's not the point. The point is it's called A diminished for a reason. Calling the note D♯ actually makes the interval an augmented 4, so then it wouldn't be a diminished chord!
Does this only apply to diminished chords or are there other chords that this applies to?– user63382Sep 25, 2019 at 13:51
@guerrier This applies to all harmony. One would never spell a C major chord as C F♭ G, for example, and G♭ major doesn't have a B♮ in it. It's just enharmonic spelling convention. Sep 25, 2019 at 17:17