How to convert the audio clip of a chord to a 7th. or a minor

I am not completely understanding your question
 
I THINK you are saying that you have purchased a sample CD that only contains basic Major chords?
 
Their "answer" of saying that the "relative minor" is the same as the major chord is absolutely incorrect!
 
If you have upgraded to Melodyne Editor then you could achieve what you want using the "polyphonic" pitch correction
 
This could (in theory) allow you to select relevant tones within the chord and move them around to create Minors, 7ths, etc.
 
I am not familiar with this type of sample CD so hopefully others will be able to expand and come up with other options for you

If you have relatively clean guitar or piano chords you can change individual notes of a chord with quite good results with Melodyne Editor, so I have heard.
If there is distortion, reverb, or other effects you may run out of luck. Melodyne is, anyway, the only way to change, say, a D to D7. Simple pitch change, OTOH, can be done in many ways and with many VSTs.
 
Anyway, trying to make songs by changing individual notes of basic chord samples is so slow and tedious that you're 100% sure to loose your inspiration! Getting a guitar VST like RealStrat or similar is the way to go, IMO, if you're not recording your own guitar.

Well... as has been alluded to here, you are going to have a heck of a time trying to manipulate an audio chord to go from major to minor. However I have a suggestion that probably won't work and would be rather time consuming but might be an interesting experiment. If you add a low E to a G major chord technically you will create an Emin7 chord. If the samples of the chords are all consistent what you could try doing is take the E Major chord sample, look up what frequency on the frequency spectrum the primary tone of E in the chord is (there are plenty of charts detailing the frequency in hertz of various notes) then use a narrow band EQ to isolate the E note while eliminating all other frequency (the overtones that create the quality of the chord).
 
Then create two tracks. In one put your G Major chord sample and in the second put your new E note sample. Blend the levels until they sound right and bounce them to a single audio file. Now you have an Emin7 chord.
 
You will want a very precise EQ for the extractions and might want to add some other effects like compression to smooth the new chords out before bouncing.
 
This however likely will not sound ideal but could give you an idea of how notes relate to frequencies and how various chords of different qualities are created.
 
Thing is though there are plenty of MIDI tools and techniques to create any chord you want using any instrument you want. You can then bounce what you've come up with to audio so they can be manipulated like a regular audio clips or sample.
To take this even further you can use this EQing method to isolate specific notes or intervals of chords that appear in other chords and again use multiple tracks to blend and bounce to create a new sample.
 
 
 

That's why it'd be best to find a chord that uses a few notes of the desired chord like the G to Emin7 example. Then you get more of the natural interplay. However with a bit more work it might be possible to isolate some of the overtones in the EQ note extraction phase by using multiple bands. This however would require a more in depth knowledge/study of specific note frequencies so you can isolate the overtones at the 5th interval and whatnot. Using a frequency analyzer would be useful to see where the overtones of specific notes lay. That however would have to be done with single notes played on the sample instrument... not derived from the chord. Like if it's a guitar sample play that note on a guitar and look for the spikes. If they match up in the chord sample then include those frequncies and use your ears to double check.
 
Certainly not pretty and I doubt it would sound all that great but it's an interesting thing to think about. I may play around with this at some point just out of curiosity.

As you say, theoretically interesting, but not very practical.
 
Wrong tool for the job.

Bristol_Jonesey
As you say, theoretically interesting, but not very practical.
 
Wrong tool for the job.

Indeed. There are so many MIDI options with things like DimPro getting a decent chord sound for almost any instrument is simple.
 
One thing that is curious about all this though... what kind of patch set limits the chord qualities in this manner? Seems kind of useless being completely stuck using Major chords.