I duplicated the track, hard panned, and then shifted one of them over about 30ms until it felt more open, but before I could really hear it. Then I used a plugin (Vitamin) to bring the lows and low mids back to the center to eliminate that weird super stereo effect you sometimes get with the phase shift. Think it came out decently well
That works quite well. I do hear the delay on the transients dragging to the right, and it would be best if that could be avoided (maybe by using a bit less time-shift/delay, 30ms is around the threshold of becoming obvious to my ear), but it sounds natural like a slap echo off a side wall, making it natural enough. Good idea recentering things by frequency range.
You might try using the original mono channel as Mid channel and the time-shifted/delayed channel as a Side channel. That will make the delay manifest symmetrically out to both sides from the center, and make the stereo effect more symetrical in the mids and highs. May still need to use the Vitamin plugin to recenter low frequency content though, because although the delay will be symmetrical, the polarity inversion applied to the right half of the Side channel is likely to cause low frequency attenuation on that side when mixed with the Mid channel.
I recently stealthed another classical performance using (2) at853Rx's cards on the side of my head and a quick AB comparison revealed to me that the true stereo recording was much more full, open, and rich sounding compared to the faux stereo. It's actually a terrible comparsion since it's different mics, recorders, performers, and venue but I was sitting in very similar spots in relation to the stage. Classical music might not be the best genre of music to try this with.
I'm curious how this would sound on a stealth stack recording of loud amplified music. [..]
Yeah, real stereo ambience always sounds richer to me. Sometimes surprisingly so. Its very easy to forget by how much when comparing the pseudo-stereo to mono. But producing good pseudo stereo is worthwhile as an improvement over mono as long as it sounds natural.
Classical may be one of the better responding genres of music for the application of this because it tends to be strongly dominated by diffuse reverberant room sound, which is easier to fake with pseudo stereo techniques than strong direct-arrival stereo imaging that's far more discrete and stereo position specific.
I suspect it would work nicely for a stack tape that would benefit from additional stereo interest and ambience. A while back I posted about stack taping using two microphones oriented such that one captures the PA stack as normal, and rather than the other being oriented the same way and thus generating little stereo interest, positioning the other microphone on the opposite side of the taper facing away from the stack and toward the audience and room. The idea being to reduce pickup of the stack in that channel as much as practical and maximize pickup of audience and ambiance in that channel. Then use the stack facing channel as Mid and the room facing channel as Side. Again, you'd probably need to recenter the low frequency content due to cancellation on the right side.
I do intend to stealth more classical and I need to find a different hat or setup.
PM me if you like for discussion on that.