Removing a loop from a mix

Hi Luggers,

I have a good one for you: I require a way to remove a know loop from a mix using phase cancellation. Here is an example:

Take a loop, put it on to 2 tracks starting at the same time and tempo. Add the gain plug-in to one of the 2 tracks and flip the phase. As long as you have the same loop and the levels are the same, you should here nothing... one waveform is the exact opposite phase, the result is null.

Sounds easy, except then 1 of the tracks has had new stuff added, the tempo is slightly faster, and there is no way to get ahold of the unmixed tracks to see what the exact tempo (and additional eq) are.

I need to be able to minimize the mixed in loop so I can add more or newer loops as an example for a client.

I need a tool that will allow me to find the exact timings of the 4 kick beats that happen each 1/4 note. It would need to either make a midi note or let me see some kind of a ready out so I can resync the 2 loops.

There used to be a few things out that did that (AU or VST that would measure the 2 tracks and tell you the differences, which was faster, so you could tempo match.

Now, before you say"try flex time" or other time stretching methods, that will change the actual waveform, so the phase cancel will not work. I already tried it, and was only able to remove about 1/4 note worth of the loop, with a heck of a phaser effect on each end of that (cool effect, but not what I actually need).

So, anyone have any suggestions. I have spent hours on this already and the only way I can think that would work is something that would be able to detect the attacks of each part, and tell me the difference. I could calculate the right amount of detuning to get the 2 loops in perfect sync, then hit the phase and no loop. Like magic ;-)

Is this only a drum loop? There is a product called Drumagog that will translate an audio track so you can replace the drum sounds with better sounding drums samples.

If you have a ton of other stuff already mixed in with what you don't want, it would take a lot of narrow Q parametric multi-band EQ to try to salvage it, even will new drum samples.
No that won't do what I need... I need a plug-in that will let me measure the difference in time between 2 loops, from the start time to each 1/4 note kick beat, so I can properly align them.

This is the ONLY way to remove an existing loop from a mix that I know of.