[Smt-talk] Early Tritone Sub

[Dmitri Tymoczko]

> I'm assuming the passage you refer to in Rhapsody in Blue is the F- 
> major "dominant-seventh" chord in bar 21 of the big E-major theme  
> (Andantino moderato) that leads to a return of the main theme in  
> bar 23. On the second half of bar 22 the C descends to B (with the  
> bass F acting as a grace note to this B). What's unusual here is  
> that the E-flat (the seventh of the F-major chord) becomes  
> enharmonically transformed into a D-sharp (the third of the dominant).

Yes indeed, that's the passage -- and you're right, the F7 leads to a  
B dominant, so it really isn't a "tritone substitution."  It's more  
like a "tritone embellishment" where V7 is embellished with its  
tritone transposition, bII7.  (You find this sort of thing in jazz  
too, BTW.)  The key point here is that tritone-related dominant  
sevenths can be related by the two-semitone voice leading (C, E, G,  
Bb)->(C#, E, F#, A#), with an enharmonic respelling of the seventh.

> A similar enharmonic transformation of the seventh of a flattened  
> II7 into the leading-tone occurs in Brahms Intermezzo in B-flat  
> minor, op.117 no.2. In bar 67, Brahms writes a "dominant-seventh"  
> chord on B-natural (=2 in B-flat minor), and this leads, most  
> expressively, to a V4/3 chord in bar 69. In the Brahms extract, I  
> read the "dominant-seventh" chord on B-natural as a bII7 chord that  
> is expanded through a sequence in seventh chords from a IV7 chord  
> (bar 65).

Good point.  There are actually plenty of examples of this sort of  
thing.  For example,  Schumann, “Chopin,” (from Carnival), mm. 11-13.  
Or Chopin Nocturne Op. 27 no 2 (D7->Ab7).  Or the Tristan Prelude  
(right before the key change to A major, albeit with the voice  
leading a bit disguised).

> Speaking of true dominant-seventh chords with a lowered fifth, what  
> about bar 7 of the Passacaglia movement in Brahms's Fourth  
> Symphony. Isn't this best understood as a V4/3 chord with F-sharp  
> lowered to F-natural (cf. the Gershwin extract cited above).

Sure.  Also Brahms Op. 76, no. 2 (initial cadence on E major), or the  
end of the Schubert String Quintet, etc.

My own view is that tritone substitutions can always be described in  
two ways -- for instance, you can describe bII7 as "really" being  
viio6/5 with a lowered third.  (That is, in C major the diminished  
seventh {D, F, Ab, B} becomes {Db, F, Ab, B}.)  Or you can say that  
"the dominant has been replaced with [embellished by] its tritone  
transposition."  What's interesting about the substitution is that  
both descriptions are true -- in other words, tritone-related  
dominant chords can often be connected by very efficient voice  
leading, so that chromatic alteration transforms one into the other.

Now in the case of V4/3[b5] it's almost certainly true that the  
"lowered note" interpretation was the original one, with the "tritone  
transposition" interpretation coming later.  But even in the  
classical era, I would imagine, the augmented sixths were understood  
to have this ambiguous status -- being both semitonal alterations of  
V/V (or viio/V) and also being (potentially reinterpretable as)  
dominants of bII.  I think the same basic voice leading mechanisms  
are at play in both the tritone sub and in traditional augmented  
sixth chords.  (Modulo, of course, the general voice leading issues  
that Nicole Biamonte mentions in here MTO paper on the subject.)

DT

Dmitri Tymoczko
Associate Professor of Music
310 Woolworth Center
Princeton, NJ 08544-1007
(609) 258-4255 (ph), (609) 258-6793 (fax)
http://music.princeton.edu/~dmitri