Speaker Placement suggestion for a room with big opening in wall at one side

I remember a setup at a friends place where he had his speakers in the opening of a square bay window next to the walls of the bay but I don’t remember whether they were flush with the wall or into the room a bit. Over time he had some Celestions with ribbon tweeters and replaced these with Townshend Glastonbury 2, The latter sounded excellant. He designed hifi for a living and became quite well known for his phono stages but I’ve not seen him in years.

 There’s another setup I know of where a pair of SBLs are back against the walls either side of a bay, this won’t suit the Cremonas though.

You could try something like the first setup and experiment with speaker’s relationship to the walls either side of the gap, I’d start with the fronts flush and very close to the sides of the gap and then bring them forward incrementally and hear how the sound changed. If this puts the big window behind the listening position this may cause problems though.

My room has two large openings (entrances) on the right wall and back wall. A bay window on the left wall and an angled corner adjoining the right wall to the back wall. Throw in a vaulted ceiling. Less than ideal for precise imaging, yet quite good at reducing typical reflections. Nothing I can do about the logistics so I take the good with the bad. 

Speaker placement will be a personal choice, and consider altering the listening position as an equally important variable. Trial and error the best approach. I'd say use painter's tape on the floor to identify experimental positions and use a logical progression. Label your trails on the tape and keep corresponding notes, focusing on positions that yield tightest bass. Then go back and winnow down from among the best positions. In a smallish room leaning your head forward a foot or two in your seat can make a subtle improvement.