Prelude in C (JS Bach) - Analysing

[rainyday]

Hello pianostreetforumguys!

I'm a self-taught amateur who has been playing the piano for about 3 years. Lately (let's say the last couple of months) I've been trying to get a better grasp of the theory behind the music. I've read two books about the basics of composing & harmony and did some analysing practices, mostly on pieces I already could play. Some were way too complicated for my puny head (moonlight sonata 1st mov being one of them) but I was quite successful with some easier pieces.

Yesterday I gave the "Prelude in C Major by JS Bach" a try. I heard it with a friend by accident and some of the chord progressions sounded interesting, so I went off to work/study! At first I thought I was going to breeze trough it because the first page is pretty standard. However when I came to the second page I started to get quite confused. I worked about 5-6 hours trying to play (which is not really a challenge is it  ) but most of all trying to understand the piece. Usually I would ask a friend of mine, who is a great guitarist, to take a look at it but alas! He's on vacation for a couple of weeks. I've been thinking a teacher would be really handy but sadly I really can't miss the money.

So I'm turning my hopes to this forum for some analysing help! I'll add my edited sheet music to make things much easier. I did it with print screen and paint because this computer lacks quite a lot of software :p



- 1st page: I think it's pretty much correct. The * means the modulation to G.





- 2nd page: I'm not sure about measure 12, 13 & 14. I think he's using the E° as the VI of G to go to Dm from which it could be the II. Then doing the same with B° which would be VI of Dm and VII of C. The ** would mean it's in Dm buuuuuuut... I could be totally wrong here.

- Then measure 20, 21, 22 & 23 confuse me as well, mostly because of the chord in measure 22. At first I thought the C7 would be preparing to make a little trip to F but the chord in measure 22-23 kind of messes up that idea.Tbh I find diminished or augmented chords quite confusing in general   I'm always confused how I should interpret them. As it is, I just looked at them from C major perspective.





- 3rd page: I think its mostly correct. However because of my confusion at the end of the 2nd page, I might be interpreting the G's/C's in a wrong way. I'm looking at them in C major but because of the chord in measure 28... I could think it's actually in G. (As in to me it only makes sense as a diminished7th VII from G).





Soooo that's it. I'm mostly concerned about measures 12, 13, 14, 21, 22, 23 & 28. I'm not sure if anyone is up for it but my thanks in advance!!~~

[bachbrahmsschubert]

Hi rainyday,

A few errors, but overall nice work. Let's go page by page.

Page one:

- I'm nitpicky about this - when using roman numeral analysis, it's very important you use lower case lettering for minor chords. So measure two is not II, but ii. Also, I wouldn't consider the C as a pedal tone, I would label it as a ii4/2, as the 7th does resolve down properly.

- I don't know if you've learned labeling chord inversions as I don't see that you've labeled the correct inversions. Measure three would be labeled a V6/5.

- The A minor chord in measure 5 is not the pivot chord to G, measure 6 is the pivot chord. The correct label for the chord in measure 6 is V7/V, from then on you would analyze in G.

- Measure 8 is a IV4/2 and measure 9 would be labeled as a ii7.

Page two:

This is where it starts getting chromatic and tricky. It doesn't seem that you've studied secondary dominants, so of course measures 12-14 would be a foreign language to you.

- We are still in G major on measure 12, the chord is a viidim4/3/V. Please note that when writing this out the 3 is written under the 4. Don't be confused by my abuse of the "/" (however the V is separated by a /). You already know how to label a diminished chord.

- Measure 13 is a v6 chord. Notice that it is minor and not major. Measure 14 is another secondary dominant and our pivot chord back to C major. It would be labeled viidim4/3/IV in G and viidim4/3 in C.

- Measure 16 is a IV4/2 which goes to a ii7 in measure 17.

- Measure 20 is a V7/IV which resolves correctly in measure 21. No need for that question mark!

- Measure 22 is a viidim7/V. Measure 23 is wrong. What edition do you have? I see what happened... You have a measure missing. The measure written in place of 23 is measure 24. No wonder you're so confused. Anyway, the CORRECT measure 23 is a borrowed v4/3/IV.

Page three:

- The CORRECT Measure 24 is a viidim4/3.

Your measure numbers are off now, so I will go by what measure numbers you have on the pictures you posted.

- Measure 28 is a viidim7/V which resolves to I in measure 29. An unorthodox progression, but he's allowed to do it because of the pedal tone G he uses (Bach is amazing).

- Measure 32 is V7/IV, measure 33 is just a IV, no D minor.

Good work, I hope I wasn't too confusing.

Some things you might want to look up: pivot chord modulation, secondary dominants (aka applied dominants), chord inversions, pedal tone.

Best wishes,

[zolaxi]

This Prelude is certainly a great exploration of the key of C maj and should be seen as such throughout.

So I would read bar 5 as a VI 1st inversion.

Your other bars of concern: Bar 12  dim7, bar 13 II, bar 14 VII7, bar 21 IV7, bar 22 dim7, in bar 23 C is the non-harmonic tone carried over or suspended from  bar 22 resolving to B in bar 24, so bar 23 is a dim7, bar 24 V7

In bars 24 to 31, the G in the bass is regarded as a dominant pedal note. The harmonies above the pedal should be regarded separately from this note. Note also the 4 bar pedal on the tonic to conclude the piece.

Oh, bar 28 VIII of V (root II).

[rainyday]

Wonderful replies, thanks to the both of you for taking the time. I'll head to the local library tomorrow to print them, so I can take them closer to my piano and my original sheets.

My excuses for the lack of correct notation. I actually did read about the right notations when it comes to inversions, etc. However I never gave it much value myself.

I did read quite a bit about the pivot chords but in my study book it is defined as a chord that "fits" in both scales. So according to this book, the pivot chord is the Am and not the D, because the C scale does not share the f sharp. Actually I took a quick look at the book and it literally says that we should consider the Am as a II from G. (because it is preparing the for the D7 in this case). However this book is quite new (2010) and it might try to "break trough" the older/classic vision?

I don't think I've heard about secondary dominants or pedal tones! I'll try to search trough my books and see if I can find anything about them. If not, I'll take a peek on wiki or something.

I found the sheets on some webpage, so yea there could be a measure missing.


Thanks again guys,

Greets~

[bachbrahmsschubert]

I did read quite a bit about the pivot chords but in my study book it is defined as a chord that "fits" in both scales. So according to this book, the pivot chord is the Am and not the D, because the C scale does not share the f sharp. Actually I took a quick look at the book and it literally says that we should consider the Am as a II from G. (because it is preparing the for the D7 in this case). However this book is quite new (2010) and it might try to "break trough" the older/classic vision?

Pivot chord modulations will often times have notes that don't belong to both keys. I don't understand why this book would say that. Composers always modulate from tonic to dominant using V7/V as it is the easiest form of modulation.

Never the less, glad to have helped.

[scottmcc]

Many, if not most, of the rules of music theory, chord progressions, and harmony were written based on works of Bach.  The cantatas were the largest source of the same, especially for the satb rules, but clearly the wtc was a large source.  As such, you've chosen a great exercise.  You should also look at the alternate version of this piece from czerny's edition, which had a far less daring progression in the middle. 

And a look at the fugue when you get a chance.  It's a good one.