Advice. Driver placement on OB baffle

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After reading tons of stories and reviews on OB speakers I had a rummage and decided to cobble something very rough out of bits and pieces I had on hand.

I have a set of HIVI 10G 10 drivers and a pair of Tymphany HDS 164 mids, a selection of tweeters so I started and put it all together. I had very limited cross over components but was determined to have something operational by lunch time Saturday and I did. The HiVi driver is the same sensitivity as the Peerless so was a bit quiet, so I put an Lpad together (out of closest to calculated resistors I had) on the Mid, ran it full range with a 1.8mH inductor (only ones I had) on the 10". With a Morel D33 tweeter and a fostek ribbon alternatively tested the sound blew me away. A bit than and tizzy but given the impedance could be anywhere and the crossover values would be lucky to be in the park I am convinced to do a Rev. 2.

I plan to make a nice frame and wings with a replaceable centre baffle so I can try different drivers etc on a simple replaceable piece of MDF.
So my questions, In an OB how important is placement of the drivers relative to each other? Is it less important than in a box given the lots more sound radiating from all over the place from the rear contribution?

In an attempt to keep the size as small as possible I plan to keep the size fairly square and given that I plan to keep the baffle and driver close to the floor, it will probably put the tweeter a little lower that ear level. So I plan to cant the speakers back to address that.
What problems am I creating given these desires?
Thanks in advance, Onslo.
 
Thanks Judhazi and Pete. Both terrific resources.

Any thoughts on canting back a few degrees? I expect time alignment would be slightly improved but that is probably less important in a dipole too given that the rear contribution would be masking some of that and that the rear time alignment would be all over the place.
Reflections off the floor would be another consideration.
 
Canting back 5-10¤ is good, in most cases it gives (a little bit) better ta and helps mid-tweeter summation. It also gives better ta backwards and thus smoother overall balance! Front and back sound spectrum and radiation should be as symmetric as possible, and off-axis smooth too.

The greatest challenge is usually between 1-6kHz, which is also the most critical range for localization and sound signature of instruments. Long and short wavelengths also get reflected (and summed) differently, so typically we see nasty zigzag in measured response at listening spot, between 200-800Hz. Speaker voicing must be done by listening, not by looking at on-axis measurements or simulations!

Speaker placement and rotation are very critical, OB's need space to breathe well! Position on the long wall of the room is good, but don't mess it by sitting too close to back wall! We must remember that our sound perception system masks many "problems" that we can see in measurements!
 
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