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I'm also interested in this question. Very small room (8X14), so open baffle isn't as attractive as a smaller box, but I like the cost and DIY factor...
Ideally the travel time of first reflections (shortest reflection distance from speaker to side wall, front wall, or ceiling) exceeds direct travel time by at least 0.011 milliseconds, so that the brain can differentiate between the two and thereby avoid smearing. That delay equates to 12.1 feet of total increased travel distance for first reflections vs. direct distance. So the open baffle should be at least 6 feet from the front wall (total travel distance from driver to wall back to the plan of the baffle). Short of that you start to get a "wall of sound" versus discrete imaging (which helps add natural resolution/detail). Note that many recommend pulling speakers (except for "speciality speakers) 3 - 5 feet away from the front wall, but with bipoles or dipoles (which open baffles are) half the energy aimed at the front wall so this distance becomes more critical, thus the emphasis in this case. Means to reduce room effects include near-field setup (maximizing the first reflection delays), absorptive room treatments (the classic LEDE, live end - dead end, treatment scheme with absorption at the speaker end of the room and the opposite end being untreated tries to address this phenomenon but no absorption product is 100% effective), diffusion (only effective down to about 1,000 Hz due to size of sound waves that are inversely proportional to frequency), limiting bass output, or using multiple bass sources (search Audio Circle for "swarm").Speaker type is a personal choice and cannot be intelligently done without auditioning. Open baffle tend to have a diffused (undefined imaging), lightweight (poor bass extension/output), lively (dynamic) sound compared to monitors. Beyond that two of the primary driver selection criteria are Qts (a measure of compliance, loose vs. tight) and Xmax (maximum in and out travel distance of the cone). Open baffles don't add compliance, so drivers used should have a high Qts (around 0.9) and open baffles don't add bass reinforcement, so drivers should have a high Xmax (higher the better as this limits how much air the driver can move - defining bass output). Horn loaded drivers should have the opposite traits with other "boxed" drivers being in the middle. So comparing ideal open baffles vs ideal "boxed" designs would also involve different drivers, therefore allowing only for broad generalizations.
This is starting to get OT a bit. Sorry to the original poster but I figure it may be helpful to the OP also. JLM, I thought 4 feet from wall was enough for open baffle....thought I read that in a number of places. 6 feet is waaaay out for a small room. You sure we need 6 feet to get the distinct separation between original wave and the reflected wave? Also, you mention diffused and yet I read some comments from OB owners who talk about incredible/precise imaging.... I'm confused. I like pretty accurate imaging and yet also a sense of scale/size and depth...Thanks,UL
I am thinking of getting a pair of the Wild Burro Betsy with mini me baffles with wooden phase plugs. How do these compare to the Omega speakers with single RS5 drivers / bookshelf model? Ger.