The 2L recording I mentioned earlier, "Souvenir," is inspired by early stereo 3-channel methods. As bass is usually cut in mono on vinyl, Lindberg of 2L decided to move the Double Bass and Celli to the center of the image, and to have the other voices of the string orchestra sit mixed, i.e. not in sections but next to other voices, in symmetrical arrangement.
This aids in the weighting of the stereo image on the record, as the bass is not off to one side (usually the right in a string orchestra). As 2L had already decided on modern DMM cutting, with a deep enough groove for precise bass rendition (a weakness with early DMM), they could focus on getting an accurately represented bass in the center, and then expand the sound stage with the L/R information.
That is an approximation to what we can see in this photo from Sinatra's listening room in Palm Springs, where the center channel is used to add weight (imagine timpanni that are usually in the back and center of a symphony orchestra coming from that speaker, instead of being summed by L/R).
While a 2-channel home system lacks the center channel, the two-step process adopted by Lindberg still helps.
In the mix, priority is given to the information registered by the center channel microphone, and the L/R microphones were used to expand the image and add detail. He described the image he was after as a "tree", where the center channel information is the trunk, the front L/R microphones provide the branches and the back L/R microphones add foliage.
Because of the symmetrical placing of the orchestra members, the simile of a tree makes perfect sense. There is still a lot of point-source stereo information, but the overall blending, plus the centered weighting, gives a realism that is rarely experienced from traditional 2-channel recordings, in spite of this being 2-channel vinyl.
Here's a diagram showing how they set up for the recording session.
The 4041 microphone directed towards the double bass and two of the celli is the center channel microphone. The 4003AP mics were used as described above, to register the "branches" (front mic's) and "foliage." (Back mic's)
Note the mixed voices seating, which had orchestra members playing away from their sections: Violin 1, Violin 2, Viola, Violincelli. Because of their long time together, the orchestra members quickly adapted to the unconventional seating, actually preferring being closer to what the other sections were doing.
(When I asked, Lindberg explained that the microphone close to the double bass is only used to record LFE for the 7.1 release, and that the information from this microphone is not used on the vinyl.)
