Maybe everyone already knows this and I'm late to the party, but I stumbled on this technique by accident and it's pretty mind-blowing.
 
I was recording an audio example for gibson.com of how to use the QuadCurve EQ to shape the piezo sound of a J-35 acoustic guitar. The audio example involved strumming chords (no arpeggiation, single notes, etc.) - the kind of rhythm guitar part you'd play behind a singer/songwriter.
 
By creating a Region FX and invoking the Percussion algorithm, I can transpose an individual chord as one "unit." It's not the same as polyphonic mode in that the notes aren't broken out separately, but I was able to transpose individual chords and entire tracks up and down 4 semitones with acceptable audio quality. After that you start to get the Darth Vader/Mickey Mouse effect, but in many cases it's still useable.
 
So yes, you read it right - polyphonic acoustic guitar rhythm track transposition with Melodyne Essential!
 
 

But wait...there's more. I then created a copy, took off the Region FX from the copy, and transposed it by the same amount using the Process > Transpose option. There were just enough differences between Melodyne's idea of transposition and iZotope's that there were some cool flanging effects in mono, and quite a widening effect when spread in stereo.

Which iZotope are you using for this? It sounds interesting, but I'd still rather play my guitar parts(bass, mandolin, etc). I suppose there are all kinds of other uses for it. The fact that Melodyne can do it, is good to know.
 
Michael

I just tried this with an entire mixed song and was able to modulate it up a semitone...but also, the song was broken up into individual blobs, so I could take like just the chorus or just the first couple chords of the verse and transpose. The quality isn't quite as good as the iZotope algorithms with complex material but it's definitely useable.

AND...you can turn off snap to grid and transpose using intervals smaller than a semitone! An X-Series first!
 

Sounds interesting. I have been using zplane Elastique Pitch for simple pitch shift. Might need to combine approaches to see what happens.

pentimentosound
Which iZotope are you using for this? It sounds interesting, but I'd still rather play my guitar parts(bass, mandolin, etc). I suppose there are all kinds of other uses for it. The fact that Melodyne can do it, is good to know.
 
Michael

I'm using the iZotope pitch transposition algorithm in Sonar. But maybe I wasn't clear - I'm applying this to a rhythm guitar part I already played. The cool thing is that I was able to transpose the entire part up or down with decent sound quality. The fact that Melodyne breaks the part into individual "blobs" so you can transpose some chords or sections but not others individually is just icing on the cake.
 
And the option to transpose by only a few cents is really helpful, too.

scook
Sounds interesting. I have been using zplane Elastique Pitch for simple pitch shift. Might need to combine approaches to see what happens.

It's the separation of the part into blobs that makes this really interesting. I was able to drop a couple chords by a semitone to throw in some flatted sevenths, and it changed the feel of the song completely.

Yes, like chopping the track up and using clip FX bin (or automation) except relying on Melodyne blobs instead of chopping up the track.

Back in the day, the semitones option would have really helped with harmonicas, etc! I can see the advantages of small amounts and being able to transpose the end of a song, would be a great option. (or the middle or a verse to create a middle, etc).
   It's sort of "Synaptic on the cheap!" LOL
 
I'm sure you'll think up lots more ideas at the rate you're going!
Michael