I have a vocal that needs to be dropped a fourth and tuned slightly  and  has a lot of hiss and 60 cycle hum. Can't redo the vocal. So, Melodyne then Rx or the reverse?
Thanks!

Melodyne functions best on clean material, so I would do noise removal, then Melodyne.

Thanks
 

You may find that even if you can clean up the noise..... dropping a note.... or an entire vocal for the song by a 4th is going to be a hard job. The further you move from the original note, the more likely you are to get artifacts in the vocal.
 
Recording the vox again is the best way, but I saw where you said that can't be done. SO........ take your time, learn the intricacies of Melodyne and best of luck on the vocal track. Depending on the genre of the music, the artifacts may or may not even be an issue.
 
I must admit though...... a number of years back, I had a female singer who sent me a unison vocal to my vocal on a song. I wanted her to sing a harmony but she said she didn't "hear" the harmony well enough to sing it. So.... working from her unison track, with Melodyne, I was able to create a harmony vocal from her track. I had to move some of those notes far more than I was comfortable doing. And soloed, you could hear the artifacts in the track. However, with the musical instruments and my lead vox, her artifacts were nicely disguised from the average listener's ears.  So, yeah, that may work just fine.
 

Yes, there are artifacts dropping so many steps. I get a lot of distortion. However it is what it is. Unfortunately, the vocal is very prominent with only a piano accompaniment. There is not a time limit on this so I get to learn a lot. Cleaning it up first or after melodyne does not seem to make any difference. Tried various pitch shifters to no avail. Next up is wave editors to try to fix it. I don't hold out a lot of hope, but who knows.

Give Audacity a shot. If the vocal is isolated, Melodyne is over kill and too complex for what really needs to be done. Doing multiple half steps may also yield better results.

I forgot about the multiple steps. I was going to try that, so now I am investigating using the spectral analysis tool of RX2 to fix the distortion. Might work! At least I am learning to use the tools I purchased.

Regarding multiple steps.  I'm thinking that the underlying data is still going to be the same and you will have similar or worse results from the various conversions. However, do let us know if that works.
 
The problem is in the formants. Once you start moving the pitch, the formants have to be moved as well for a natural sounding voice result. I have had huge problems in trying to get the formants to line up perfectly to have a natural sounding voice once I get the notes a certain distance from the original pitch. It also depends on the original singer.

This song:  http://soundclick.com/share.cfm?id=8575294  is one where I used Melodyne to move the harmony vocal that started as a unison. The female singer's  harmony in the second half of the first section, was generated in this manner. Since it's setting further back in the mix, you can't hear the artifacts easily. It was generated using a unison with melodyne.