Can someone tell me how the chords in the measures 22, 23 & 28 fit functionally in the piece? I see that they are variant of some Augmented Sixth Chords.

If so, why 2 augmented sixth chords in succession in measures 22 & 23?

Please help.

Ref: http://www.gmajormusictheory.org/Freebies/Classics/WTCPrelu.pdf

Thanks much,

VJ

I don't see any augmented sixth chords.

M.22: F#dim
M.23: Bdim (add C: I'm never quite what to call the C functionally here; perhaps in some sense a suspension from the previous measure. But I like the effect)
M.24: F#dim over a G pedal note

How are you naming these chords?

Thanks... I was thinking the same progression as you F#dim and B dim (I thought C as more of as passing note).

But please can you tell me how the progression F, F# dim, B dim, G works?

2 diminished chords next to each other. I don't see the secondary functionality.

Again thanks for your response.

(I started to branch to augmented sixth when this progression didn't make sense to me. Looks like I am very wrong there).

a diminished chord is a incomplete dominant chord

F#dim = D7 third in bass

B dim = G7 third in bass

Thanks so much, Chris. Now the whole piece makes sense to me. Piston's Harmony book has a complete chapter dedicated to it. Its time for me to read some of Piston too.

VJ

That sheet has pedal markings. It's OT, but I think the topic is now answered, so I am surprised as I have read elsewhere not to pedal Bach. I never pedal this Prelude but do hold the LH notes, and legato the RH notes. What do the experts say?

There is the entire canon of Baroque music plus this prelude to consider. Hmm, exaggerating a bit but I think this piece causes big problems because it sounds crazily beautiful with the pedal but Bach had no instruments that had a pedal so it could never have been played that way. Of course, to take that further, this was fully romanticized by Gounod in his Ave Maria.

This was one of the first pieces I studied when taking lessons; but it wasn't my usual teacher I studied this with (summer lessons - take your pick.) Anyway, what he said was - you can play it like "that" (pedaled) but I won't let you move on until you can also play it in a more baroque (no pedal) style. And then he played me Glenn Gould's version - which he said I would probably hate - as reference.

So, there you go. Play around with it but a more authentic performance is almost certainly quite fast and much less legato.