John Sheerin is in a better position to know, but I believe that most Daytons are Eminence sourced. In pictures the motors are different but the frames appear identical between the LAB12 and the Titanic III. Another giveaway is the lack of a 'Made in China' stamp on the Daytons, as well as packaging identical to Eminence's. I could be wrong, but I don't believe that Dayton (Parts Express house brand) actually makes anything themselves.
I do vent my midbass boxes, though the venting is optional. With venting the Fb is lower, but SPL a bit lower as well around Fc, so vented vs non-vented is a matter of whether you want a wider bandwidth or maximum SPL. I recommend that if you run them stand alone you vent, but if used with a sub that you stay sealed.
Do you happen to have measurements of a speaker of yours that is vented verses one that is non-vented, with everything else the same for comparison? I'd like to get an idea of the differences. Thanks, Ralph
Yes, I've made several of my midbass horns both sealed and vented. Send your email address to me at billfitzmaurice@aol.com and I'll send you a picture of a chart or two.