I recently got a few tracks to put some vocal ideas on - however - I've found that the original track has guitar in drop d - however the overall tuning of the track is somewhere between d and e flat - I first heard this - but then opened up a small portion of just the guitar in melodyne to make certain I wasnt crazy.  So - how would you adjust melodyne so that it detects the real tonal center of something that may be not necessarily at 440....   and then snaps to the grid of that new tonal center.

Is fixing the guitar pitch an option? Sounds like that might be the best bet in the long run. Depends upon how off it is as to whether this can be done easily and without artifacts.

I've hardly used Melodyne but have you looked for some kind of "Cents" adjustment option? Since 440 is obviously only one commonly used tonal center it would make sense that they would account for other tunings. So let's say the guitar track was laid down at A 335 you'd change Melodyne to set it's pitch grid to 335 (obviously).
 
However... if it is ONLY the guitar (and not a pile of tracks all tuned around the guit) I agree with Craig. Pitch correct the guit then work around that from that point forward.
 
Since you are tuning the ENTIRE guitar track you should be able to do this even in the basic version of Melodyne (it does not require the more advanced Polyphony feature). Basically you'd select ALL the blobs and tune the entire guitar track to reflect A 440. Of course not all the notes will match up to the pitch grid but it does not matter. The guit is in tune to itself and you just want to nudge the overall pitch toward 440.
 
May require a good ear or some nice clean open notes to set the base pitch so look for a single sustained note that is clearly an A or an E or a D or something and use that as you tuning point. Turn off the Melodyne snap and move the entire track so those clear open notes land where they need to.
 
To check out whether it work maybe toss a synth into the project (set to A 440 of course) and noodle around to see it sounds in tune with the guit. If not adjust a little more.
 
Just some ideas.
 
Cheers.

Beep has it right, you can adjust the pitch in the settings menu.
Although honestly, I personally never use the snap to pitch, I go by ear. Assuming you sang with the guitar part, you should be close and you can hear where you are off. Whether or not the note visually aligns with the line means exactly nothing.

Sanderxpander
Beep has it right,

A scary though. ;-)
 

Although honestly, I personally never use the snap to pitch, I go by ear.

Yeah... snapping pitch rubs me all sorts of wrong in these scenarios. Totally unnatural. The few times I've used the auto features in Melodyne it's the whole "adjust by percentage" slider thingie then anything that still sounds weird gets done by hand/ear.
 
But I'm more of an audio track guy and prefer "organic" pitches (and timing) that work well together over that hard correct/"perfect pitch" sound.
 
I should get over that aversion though if I intend to create for the current industry. Just won't happen on my own material is all.

I only correct notes that sound off to me, I don't think I've ever done a blanket "correct pitch" thing on an entire track. If I can't hear it's off, I have to trust that others will hear it even less. Also, I mostly work with professionals which helps in that the source material (or an alternate take) is usually very close to the mark so I can stick to small corrections. If I had to do an automatic correction over a lot of material I'd tell whoever it was to sing or play again.

Sanderxpander
I only correct notes that sound off to me, I don't think I've ever done a blanket "correct pitch" thing on an entire track. If I can't hear it's off, I have to trust that others will hear it even less. Also, I mostly work with professionals which helps in that the source material (or an alternate take) is usually very close to the mark so I can stick to small corrections. If I had to do an automatic correction over a lot of material I'd tell whoever it was to sing or play again.

One thing it's good for is dealing with the intonation problems on a standard bass (which is what I've used it for). It's impossible to get a perfect pitch all the way up a fretboard even on a stringed instrument that's had its intonation properly setup (it's all in degrees of "off" and there will always be some slight pitch wobble due to the player). You know this of course 'cause you've been doing this a while.
 
But yeah... tossing Melodyne on a bass track really tightens things up in that regard so doing it as a bulk process makes sense.
 
It also makes any bass reinforcement (doing an audio to MIDI conversion of the bass out to a softsynth) sound more in tune.
 
Anything else though... I'd probably go section by section. As a guit player I would even touch my own tracks (I'd just rerecord) but I do have some things in mind for some live parts of other players where they missed their "CAGE" by a semitone... so I'd snip around that and Melodyne it up a bit.
 
Meh... it's just really cool we can do this stuff... AND that Cake tossed this functionality in as a "free" add on.

Beepster
Since you are tuning the ENTIRE guitar track you should be able to do this even in the basic version of Melodyne (it does not require the more advanced Polyphony feature). 

I have not used Melodyne, but I do wonder what polyphonic means in this context. I expect that the algorithms that work well to re-tune a true monophonic source (like a single voice) would not work so well it there is a chord playing, even on the same instrument. If you are using single string bass lines, that looks like it may be monophonic, but what about a six string chord? Of course if you are trying to re-tune an orchestra...

slartabartfast
 
I have not used Melodyne, but I do wonder what polyphonic means in this context. I expect that the algorithms that work well to re-tune a true monophonic source (like a single voice) would not work so well it there is a chord playing, even on the same instrument. If you are using single string bass lines, that looks like it may be monophonic, but what about a six string chord? Of course if you are trying to re-tune an orchestra...

Yeah, I wonder about the polyphony effectiveness as well. I am on Essentials (the version that comes with Sonar and does not have the polyphony capabilities) so have not had a chance to check it out.
 
Others here though do and say it works pretty well on things like guitar BUT with some caveats. The main one being you need a clear/clean signal source. So it works well on detecting and tuning individually notes in a chord but the individual notes need to be well defined and clear for the detection to work.
 
To me that seems like a nice laid back chord progression played without any heavy distortion or other effects could be manipulated in a reasonably useful way. Spazz out distorted nonsense like I do? I don't have high hopes for it... even if I recorded a dry signal.
 
I honestly don't think at the speed I like to play things even using a hex pick up would provide the needed separation though.
 
It's the same reason I'm not so sure Drum Replacer will work for me at the level I would like (but I am about to test). As awesome as these tools are I just don't think they are capabable of that finite transient detection. I think it would just get blurred and the detection tool would get confused. Same reason Audiosnap has turned into a mess on me in the past in many scenarios.
 
Meh... I still gotta test this stuff out though but I do know in general whenever I've tried any kind of "auto detect/correct" stuff I generally have to go through everything and do a LOT of manual corrections. It almost makes it more worthwhile to start from a manual mindset and avoid auto fanciness.
 
For picked bass though... even at high speeds melodyne seems to do well and I could of course see it working well on vox or more chillaxed material.
 
Mayhaps I should stop being such a hyper speed spazzwad.
 
...
 
Naaaaaaawwwwww....
 
 
;-)

If there is a detectable pitch in your note Melodyne can work with it, but perhaps not automatically. Drum Replacer exceeded my expectations the times that I used it. The filters are quite helpful.