quality modulation

Hey I have been really into modulation these days and I was wondering how you judge a modulation. I have noticed that there are people who modulate and it just kind of sounds bad. But when Chris Thile or a good classical peice modulates it ends up sounding better than it ever could have if they had stayed in a strict key. Is there a manner of relating your modulated movement to you original melody beyond keeping a rhythmic or melodic motif intact?

The standard method of modulating is to use a pivot chord followed by the V7 chord of the new key then the new tonic chord (chord I).
A pivot chord is a chord that is common to both keys.

If you were in the key of C major and you wanted to modulate to G major, you could have a sequence such as
C -- G7 -- C -- F -- Am -- D7 -- G -- D7 -- G

The first key is C and the G7 followed by C confirms that. F is also an important chord that belongs to C and not to G - but then comes A minor which belongs to both C and G. It's chord vi of C and chord ii of G. Then comes D7 which doesn't belong to C, but is V7 of the target key G. It was arrived at painlessly because we went to it via the pivot chord Am - If we hadn't gone through the pivot chord Am - it might sound abrupt and awkward. Using a chord that belongs to both keys makes it a smooth transition.

From there it's a simple step to go from D7 naturally to G because it's the V7 of G (as naturally as G7 went to C). Repeating the D7 - G cadence really drives it home that we are now in the key of G. The tonal centre has now shifted from C to G.

thanks for the reply, I was refering more to the specfic intervallic relationships between you original melody and the modulated one rather then how to modulate. Like someone might say that a modulation is "compositionally sound" How is that judged?

thanks for the reply, I was refering more to the specfic intervallic relationships between you original melody and the modulated one rather then how to modulate. Like someone might say that a modulation is "compositionally sound" How is that judged?

Modulating up a perfect fifth or perfect fourth are considered the 'soundest' (is that a word?) options for repeating melodies in new keys. (not just shifted up in pitch, but actually in a new key). Classical symphonies, sonatas and concertos (of the classical, rather than modern periods) feature those modulations as an integral part of their opening movements because of the strong acoustic relationships between keys separated by perfect fourths and fifths.

You'll see several different types of modulations. What makes one 'compositionally sound' is pretty subjective - ones that hang together are sound, ones that don't aren't. (That's also true of diatonic melodies... it ain't in the formula, it's in the application!)

As Fretsource noted in his second post, modulations by fifth are actually expected in many classical forms. Sometimes it's not even a real modulation; there's a cadence like V-I in the 'old' key, and immediately after that you go charging off in the 'new' key - maybe with a luft pause for separation.

The next most common type is modulation through secondary dominants. G7 wants to move to C something - C major or C minor for a V-I or V-i. But it can go to any C-root chord, including a dominant chord type... which then wants to move to F-something. Many jazz standards take a sudden jump to someplace unexpected, then work their way back into key. A good example is Irving Berlin's "Always" in the key of F - there's a couple of C7-Fmaj7 cadences, but then it jumps WAY out of key (to Bm7b5). Eventually he works back through the series E7-A7-D7-G7-C7-Fmaj7.

After that, modulation by step (either chromatic or diatonic) is pretty common. Miles Davis' "So What" has an A section in D Dorian, and a B section in Eb Dorian.

Next would be modulation by pivot, which Fretsource covered pretty well in his first post.

Finally, you can have a modulation by simply leaping into a totally unrelated key. Usually that doesn't work too well, but in the right hands.... like McLaughlin said (I think paraphrasing Stravinsky) "any chord can follow any other chord".