Currently, there is only the option in theorytab for IV/x. Secondary subdominants are fairly uncommon, but they show up in a variety of music and it would be nice to show function instead of having to borrow a chord from some parallel mode.
Here's a good example. In the "Gusty Garden Galaxy" tab, the Abm/Cb chord is analyzed as v6. This isn't a great analysis at all, as it doesn't show the function of the chord. Really what's going on there is a "iv - V - i" in the key of the ii chord. So "iv/ii - V/ii - ii."
Another great example is Haywyre's "Insight." In the instrumental section of this theorytab, the Gm chord is analyzed as the vii borrowed from phrygian. But that isn't its function at all. It's another "iv - V - i," this time in the key of the iv. So "iv/iv - V/iv - iv."
It'd be great if instead of just a IV/x option, there was a whole option for secondary subdominants that had IV/x, iv/x, ii/x, and iiº/x.
It seems counterintuitive to me that there would be ONLY a IV/x option and no others. Especially when iv/x tends to be more common.
Hookpad (1) has had support for the ii/ secondary supertonic, however unless you could edit .hkt files directly there is no way to get them into a Theorytab. I refrained from using them in my public tabs because they never appeared in the database (unlike the pre-HP2 (#5) and (add4) chords).
Hookpad 2 allows creating secondary chords of borrowed chords. If the borrowing applies to the secondary chord itself rather than the target chord degree, then the Major and Harmonic Minor modes alone could form all the commonly used secondary chords:
- Major: V(9)/, ii/, IV/, viiø/
- Harmonic Minor: V(b9)/, iiø/, iv/, viio/
Extra qualities may be accessed through alterations or other modes. The need for creating secondary chords for borrowed chords has greatly reduced due to modulation support in Hookpad 2, and these chords are traditionally not defined / allowed either, so it would be a good opportunity to officially support them before the public release comes out.
I'm not sure I understand your response. I'm not sure what you're talking about with borrowed chords, this post was purely about secondary subdominant chords. Such as "Gm/Bb - A7 - Dm" in the key of CMaj.
You could analyze this as "v6 - V7/ii - ii," but that wouldn't be very accurate to the function of the Gm chord. It isn't simply being borrowed from minor, it's actually the iv of that Dm chord. So "iv6/ii - V7/ii - ii."
I just think it's weird to support IV/x but not iv/x.
That part indeed has nothing to do with borrowed chords, it has to do with how a particular Hookpad 2 beta feature may be turned into something that supports the said secondary chord, plus other useful secondary chords.
Although v6 is not a borrowed chord in C major here, it is a borrowed chord of the targeted ii chord's key, namely that it borrows iv6 from D minor, in the secondary key region that is D Dorian; or the whole iv6/ - V7/ sequence can be seen as a local Phrygian cadence, which comes from D Harmonic Minor, hence the "borrowing" part.
If this "borrowing" from Harmonic Minor is done in the current Hookpad 2 beta, the resulting chord progression becomes the erroneous IV6/iiø - V7/iiø - ii, as the half-diminished chord never exists. This is often not what the user wants, and even if it were the case, modulation support eliminates many needs for these secondary chords. Hence, this behaviour change could enable those extra secondary chord types without affecting any of the existing public TheoryTabs (again, the current behaviour was already present, albeit inaccessible through the GUI, in Hookpad 1).
I really hope the @Hooktheory devs could take a look into this feature again, especially since viio7/V is unavailable without those secondary chords and such "tricks" as copying and pasting chords between relative keys (Harmonic Minor and Phrygian Dominant give viio7 and iiio7 respectively, neither of which can be inverted to give the same voicing as #ivo7).