There was a fairly good discussion about this site :
http://shadowmusic.bdme.co.uk/viewtopic.php?f=21&t=18497&hilit=ripx and on Charlie Hall's site a month ago:
https://charliehall.proboards.com/thread/26049/interestingMy point was as follows:
Unless the program has enough "artificial intelligence" to know what the melody line is to follow the notes of the lead guitar (for example), there are only two sources of information available to allow separation. They are spatial separation and spectral (i.e. frequency) separation.
An example of the former is lead guitar in the left channel and the rest in the right channel or, at worst, lead guitar in the center channel and the rest in either the left or right channels. An example of spectral separation might be a tune involving only lead, bass and drums, where the frequencies of the lead have little overlap with those of the other instruments.
However, on typical Shadows tracks comprising lead, rhythm, bass and drums, there are invariably sections of the tune where the notes or harmonics of the lead overlap with those of the rhythm (they are both just guitars with the same tuning) and also possibly any strings in the backing, and so spectral separation is absent. Furthermore, there are many Shadows tunes where the lead is in the same channel as the rhythm or other sections (e.g. strings, drums) and so spatial separation is absent. On such tunes it is very difficult to get separation of the lead without affecting the other instruments. Even with a good stereo original, on some tunes we still found it necessary to reinforce some of the components that got caught up in the lead removal by playing along, e.g. the acoustic rhythm on Dance on; some of the strings and triangle on Atlantis when the damped lead occurs in the same left channel.
I have not yet found any programs that use all of the information available, and RipX seems to be no exception. I usually use a program like RiffStation (now available for free) to make use of any spatial separation and then clean it up with a spectral analysis program like SpectraLayers to make use of any spectral information. But it can be a very time-intensive process, particularly if you have to edit the tune note by note in which case I am also using knowledge of the actual tune to follow the lead line! Natural intelligence??
Paul.