I came up with a cool melody and just find out it is a diminished scale. The melody has the following notes: D D# F G# A. Most scales containing these notes are diminished (I believe all of them are but I am not 100% sure). So now I want to build a song out of it and I don't know what chords to pick or should I stick with these notes. Thanks!
This selection of five pitches could be a constituent part of a number of scales, although it is not a part of any diatonic scale. As a set of notes itself, it could be referred to by its PC Set name (Forte Number), which in this case is 5-19. This has a prime form of . (You can find this using a PC Set Calculator, such as this one.) According to this list of PC Sets, this group of pitches could be called a Javanese Pentachord. (Who knew...!?)
When writing down scales, either as letter names or in notation, it is usually best practice to try only to have "one-of-each-letter-name". This gives the correct enharmonic spelling. In this case, D Eb F G# A, would be best. (Obviously, when you have more than seven pitches this is not possible.)
Searching for "D Eb F G# A" on this webpage of All Named Scales lists your group of five notes as being a constituent part of eight named scales. However, these seem to me to be a little obscure, so are probably more of interest than of obvious practical benefit.
So, yes, the most obvious scale containing these pitches is the Diminished Scale (or Octatonic Scale). Specifically, they are part of this octatonic scale: D Eb F F# G# A B C
Notice two things about the octatonic scale:
- it is symmetrical, consisting of a regular repeated pattern of whole-tones and semitones, e.g. STSTSTST. Effectively, this means that you can choose any of the notes to equally well "feel" as the tonic: four starting a scale with a semitone step; four starting a scale with a whole-tone step. (Your group of notes is, of course, not symmetrical. So using just these, will give different effects if you choose any particular pitch to function as a tonic.)
- as mentioned earlier, this scale has to repeat a letter name, as it has eight pitches; to fit best with the pitches you listed it is best to have both F and F#.
Chords created from the Octatonic Scale:
A large number of chords can be created using the octatonic scale. In fact, using all the pitches of an octatonic scale together as a chord, gives the largest possible chord with no semitone clusters (i.e. no three adjacent semitones). This chord has a characteristic altered sound. Indeed, the pitches listed in the octatonic scale above could be described as D13#9b9#11, if one takes D as the root. And so, all of the constituent parts of this "full" octatonic chord are characteristic octatonic chords. Some of these are:
- 7, b9, #9, 7b5 if the root of the chord starts a scale with a semitone as the first step (as above).
- the following chords without a fifth mAdd9, mMaj7, mMaj9, mMaj13 if the root of the chord starts a scale with a whole-tone as the first step. (E.g. with Eb as the root using the notes listed above.)
Despite the large number of "colourful" chords that can be created using the octatonic scale, one difficulty can be creating interest in harmonic progressions as one moves between chords on different degrees of the scale (i.e. as the root note changes). This is because of the symmetrical nature of this scale type. As the scale splits into four symmetrical parts, four notes of the scale create the same extended chords, as do the remaining four notes. In other words, chords with roots on the notes of the symmetrical diminished seventh chord D F G# B are built up in identical fashion, as the chords built on the notes of the remaining notes, Eb F# A C, which are themselves a diminished seventh chord. (Yes, I know these examples should be spelt differently...!) This can make it difficult to create a variety of harmonic colours, as all the available chords tend to have a similar character. This is one of the reasons why the diatonic system works so well, as extensions are added to the basic triads the chords become more and more varied, due to the non-symmetrical nature of the steps within diatonic scales.
To my ears, a good starting point would be F7/6, F7#9 and the combination of these F13#9, as these contain your five pitches. Although this does emphasise the F as a root, which may not work well with the melody you have already composed...