Over the months, I’ve read a couple of posts asking whether it is possible to extract or synthesize surround channels from binaural stereo or non-Ambisonic surround formats. I am now attempting to do something that would appear to be simpler and more straightforward: that *something* being the conversion of conventional L-R stereo to L-C-R. My reason for wanting to do this is because I have three loudspeakers that I’m very fond of: A pair of vintage KRK 7000s and a single KRK 9000 (not with the b suffix). I want to use the 9000 as the center channel because it has as the same Focal tweeter as the 7000s, but the 9000 has a much larger woofer (the 7000s being somewhat deficient in this area). I thought it would be fun to experiment with a full-range center channel in lieu of using the 9000 (or any speaker) as a sub-only.
There’s a lot of info on the Internet about converting stereo to mid-side, but not too much about L-C-R. The simplest *fix* would be C = (L+R)/2 which is akin to extracting the mid signal from a mid-side encoding. But this doesn’t separate what is only in the left channel, what is only in the right, and what is common to both L + R. If I have a sound going only to the L channel, using (L+R)/2 would give me half of that sound on the center channel. Needless to say, signal separation would suffer. Going a step further, the left channel, L, contains the unique part of its content, l (lower case L), and half what is common, or C/2. That is, L = l+C/2 Likewise: R = r+C/2 But to extract what is common in terms of R and L is algebraically impossible because we don’t know what l and r are (l and r don’t cancel out); I suppose if we did, then there wouldn’t be a problem to begin with. The problem doesn’t exist when you have stems to work with (e.g. cinema sound track production) in lieu of attempting to extract it from existing L and R channels. Perhaps this simple exercise also explains, at least in part, why we can’t derive Ambisonic channels from non-Ambisonic sources (mathematically, it seems impossible to set up a determinant with unique solutions). Perhaps readers here have had success with a simple stereo to L-C-R converter? I have converted Ambisonic recordings to L-C-R: This is pretty easy with any number of plug-ins (I use Harpex for most of my Ambisonic processing). Thanks for everyone’s time. Best, Eric C. -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20130621/26642f65/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
