In this particular case, the difference in panning of the Tree with and without outriggers isn't mentioned in the text, and I overlooked that table.

My overall point was that Decca's proven spaced arrays show that pretty significant panning-in of spaced mics will not produce enough comb filtering to produce an ugly sound, as theory might lead some to assume.

And further, that panning-in a 3' or so AB pair to fill in the hole in the middle requires less than what was used in the 5-mic or 4-mic versions of the Decca Tree.

It happens to me often, and only discover the additional information when searching a subject using the index, which tends to tie the disparate segments together. Maybe subsequent editions and re-edits will fix it ?

It's best to be read in its entirety and combined with the knowledge from elsewhere, too... It is not the Bible - and even with the latter - we know how many interpretations there are...

I am not sure calculating is the right approach, at least not for the "artistic" approach - what sounds good is good... if you are into audio research, work at some lab or university, sure, but for everyday use, do what works for you and use the ears (talking to myself here).

And as I found out - panning and balance is key - for the recent acoustic recordings I only use very sparse EQ on some tracks, no artificial reverb and no other processing - all colours and sense of space and clarity can be changed just by different panning of stereo pairs and the balance between them.

If I am interested in a particular set-up, I would ask the one who is using it - so in this case I'd say to the OP - seek out the engineers from San Francisco Symphony Orchestra and ask them.

If (when) I simply posted a video of Daniel Hope's "Spheres" recording session and asked about the peculiar mic set-up, I'd get very different opinions around here, but none that would actually know exactly why and how they use their set-up - some more or less general opinion from those who know the system, sure - but not exactly Tritonus' answer how and why they set their mics as they do - in that particular room and others, too. It was best to ask Markus Heiland directly and be sure how and why.

"ask the one who is using it"
I am not sure if the author of the paper I cited (regarding SFSO) is even alive, here is the explanation given in the article "However, after many years of experimentation, we feel our current Main array produces a useful combination of flexibility, timbral accuracy, and musically appropriate balance for most standard symphonic concert literature."

"we feel our current Main array produces a useful combination of flexibility, timbral accuracy, and musically appropriate balance for most standard symphonic concert literature."

hard to argue with a claim that is both generic and highly personal at the same time...

more importantly, there are no recordings from the use of an alternate approach/main mic setup that could get used for a comparison.

https://www.linkwitzlab.com/Audio_pr...f_symphony.htm

here you get the full expo.

Agreed, you have to work within the constraints of the hall/management/desires.

There are some weird decisions however.
eg. they axed their centre (stereo?) woodwind support mic, because in video productions it blocks the frontal chef cam. I woudl move the chef cam 1m, instead of sacrificing the mic setup !

They also admit imaging is weak, and balance can be an issue for some music.
They can solve IMAGING by substituting the too wide centre AB mics by a MS centre mic (eg. MKH8090/8030).

They can test this and agree this is the better option (also for video !). I can give my credit card details later

Now, it can by 100% possible there is no centre hanging possibility at that stage position - making all of this stupid comment on a public forum.

As a last note, they seem to be monitoring in a small room on a 5.1 system (filling in the centre gap ?)

Regarding Davis Hall:

"Regardless the differences in stand microphone count, the overall pickup design is based on four spaced, breasted and angled, Main omnidirectional microphones. Because of the aforementioned canopy/speaker cluster restrictions, the distance between these hanging microphones is approximately 7.5'; their height above the deck is around 9'. This spread is not typical for arrangements without a center microphone. For example, the downstage microphones in a Decca tree are likely to be spaced less that 7.5'. However, after many years of experimentation, we feel our current Main array produces a useful combination of flexibility, timbral accuracy, and musically appropriate balance for most standard symphonic concert literature."

Jack Vad, who wrote the cited article, has been a "producer/engineer" with the San Francisco Symphony for many years. The SFSO has won 17 Grammy Awards over the years. I do not know (anyone know?) how many, if any, of these awards were produced by Mr. Vad (nor if the setup in the article was used for any of these recordings) , but it is likely that some were. If so, someone must like these recordings.

Yes, and the article mention the negatives about their setup. Which means you can be actually unhappy about a given situation, and still win 17 grammy awards.

The orchestra has won 17 Grammys; Vad, 2.

The bulk of his SFS engineering has been for broadcast and archive.