It's not the working out I would find difficult, it's how you knew WHAT to work out.

 

You're just psyching yourself out.

Think about it this way: You know how "vocal removal" works? By taking the inverse of one channel and adding it to the other, and how that removes anything that is mono (without panning)? So you've removed the vocal except for any reverb or "spaciousness", etc. but you also tend to lose almost all the kick/bass? That's the effect of L-R, you're just taking L and adding the inverse (-R). It's literally L+(-R). Then the *0.5 is because you want to cut the signal in half (same effect as -6 dB) because when you add two signals, all the shared info between those channels becomes twice as loud (+6 dB), right? Mathematically you're just doing x1/2.

Take the same concept and apply it to the stuff panned dead center. Anything perceived as center/mono (in a stereo field) has the same information present at the same levels on both the L and R channels. So that kick drum that is sitting right smack in the middle between two speakers has the same exact waveform present in the left channel and the right channel. Any deviation in either/both of those kick waveforms will be perceived as coming from the sides. So you just take the commonality of those waveforms and drop the differences to get the center. Divide that by two (multiply by 0.5, same thing) to cut the volume in half.

There you go.

 

Last edited: Mar 23, 2016

Thanks Rasputin, That I can follow.