Diminished scale...

It would seem so. Cdim7 is in both scales.

The problem arises if you try to use other diminished chords included in the same T/S scale that are not in the S/T (in your example you see Ddim7)... if I am not mistaken, often in these contexts, you find two diminished chords a semitone apart simultaneously.

mmm… let me give an example:

C∆ Ebo D-7 G7 C∆

would you put both T/S and S/T on the Ebo?

DrJellyfish wrote:

mmm… let me give an example:

C∆ Ebo D-7 G7 C∆

on the Ebo would you use both T/S and S/T?

I'm not sure, but in my opinion, yes

What do you think about it, DrJellyfish?

From a purely theoretical point of view, both scales would be compatible with the chord since both contain it; in practice, for diminished chords, the tone-semitone scale is used; hence the doubt arose: what would, in your opinion, be the justifications for using one scale rather than the other?

DrJellyfish wrote:

what would be, in your opinion, the justifications for using one scale rather than another?

The ear, which is always right. A teacher of mine used to say: first the ear and then the hands

Egidio wrote:

The ear, which is always right. A teacher of mine used to say: first the ear and then the hands

as Tex Willer would say: "Pure common sense"

Not just on the diminished seventh, but also on the dominant seventh, Chick Corea teaches us.....

Anyway, the reason why the D/m scale would theoretically be more correct is that in jazz the diminished seventh chord harmonizes with its own tensions, which are a whole tone above the chord notes: putting together both the chord notes and the relative tensions yields the D/m scale.

Ex.: Eb dim chord: chord notes: eb, f#, a, c; tensions: f, g#, b, d....putting them together yields the D/m scale.

If the scale is started from a degree different from those of the chord notes, you get the m/D scale, so in practice they are the same scale, a bit like natural minor and C major, with the added regularity of the intervallic succession which gives it a very particular taste that I, like all Koreans, like very much....

Yes, I have also reached the conclusion that the possible explanation lies in the tension notes.

If we were to consider the remaining notes of the S/T scale as tensions, the diminished chord would lose its identity (e.g., C, Eb, Gb, Bb), whereas with tensions one tone above the chordal notes we would have, for example, C, Eb, Gb, B and we would still perceive the chord as a diminished seventh.

From a melodic point of view, there is also a more bizarre reasoning regarding the fact that for our ear, ascending chromaticism results in being more effective than descending chromaticism;

as a consequence, having to "fill" the gaps between the chordal notes (or accordal notes, if you will), it is more natural to choose the notes that ascend chromatically towards the chordal notes, as happens, for example, in the augmented scale (e.g., C, D#, E, G, G#, B). It is indeed a somewhat extravagant reasoning, but in fact, even in the use of block chords, for example, it is much easier to manage ascending chromaticism than descending.

I think both scales can be used, but the effect is very different:

-if I use s/t I complete the scale with the minor 7th (for example, using s/t on Cdim I end up with Bb) and therefore the effect is that of a dominant chord

-if I use t/s I will finish the scale with the major 7th (B natural) and thus the effect is not that of a dominant chord/scale but more static. Some daring improvisers use t/s on maj7 chords

Yes, in fact both can be used, but with S/T (always on a 7dim chord) the use of tensions proves to be quite difficult, and then regarding the effect of the dominant chord, do you mean it on the same root? Let me explain: do you mean that Cdim7 with an S/T scale sounds like a C7?

On the maj7, yes, sometimes it is used, it sounds like a kind of delay; often the maj7 follows afterwards.

yes, one must distinguish when the diminished is a dominant ninth without a fundamental and when it is a true diminished...

Yes, I meant that.

In fact... if it is a dominant b9, the most suitable scale is tone-semitone because it contains the fundamental...

DrJellyfish wrote:

Yes, in fact both can be used, but with S/T (always on a 7dim chord) the use of tensions proves to be quite difficult, and then regarding the effect of the dominant chord, do you mean it on the same root? Let me explain: do you mean that Cdim7 with the S/T scale sounds like a C7?

On maj7 yes, sometimes it is used, it sounds like a kind of delay; often the maj7 then arrives.

Yes, I meant exactly starting from the same root, Cdim S/T scale on a C7 chord.

In the chord, even though all four notes of Cdim are present, I emphasize the (1 3 b7) of the dominant chord. The result is a dominant chord with these tensions: b9, #9, #11, 13

Regarding the delay you mentioned, I think the other scale, T/S, works better, which has b3 and b5 relative to the maj7 resolution chord

leoravera wrote:

I specifically meant starting from the same fundamental, Cdim S/T scale over a C7 chord.

In the chord, even though all four notes of Cdim are present, I emphasize the (1 3 b7) of the dominant chord. The result is a dominant chord with these tensions: b9, #9, #11, 13

Regarding the delay you mentioned, I think the other scale, T/S, works better, as it has b3 and b5 relative to the maj7 resolution chord.

Yes, but thinking Cdim over C7 feels strange to me... If we are talking about C7, the diminished should be Edim, and therefore its scale would be T/S.

mmm… on C7 the H/W has a B natural...

@ Leo: yes, I agree about the C7 and the delays generated by the H/W, but I meant the opposite effect: a H/W diminished scale sounds strange to me on a diminished chord (even if this one also contains the notes of the chord). E.g.: Cdim chord (with Do as root) + half-step/whole-step scale (Do, Reb, Mib, Mi, Fa#, Sol#, La, Sib).

DrJellyfish wrote:

mmm… on C7 the T/S has the B natural....

The T/S on E minor is: E F# G A Bb C Db Eb where do you see the B natural?

It refers to the T/S starting from DO